Sensors

Editorial

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457 KiB

Open AccessEditorial

Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology

by Vojtech Adam and Rene Kizek

Sensors 2008, 8(10), 6125-6131; https://doi.org/10.3390/s8106125 - 1 Oct 2008

Cited by 3 | Viewed by 8257

Abstract

Editorial note concerning the "Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology" special issue. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Research

Jump to: Editorial, Review

482 KiB

Open AccessArticle

Electrochemical Performance of a Carbon Nanotube/La-Doped TiO₂ Nanocomposite and its Use for Preparation of an Electrochemical Nicotinic Acid Sensor

by Jing Wu, Hanxing Liu and Zhidong Lin

Sensors 2008, 8(11), 7085-7096; https://doi.org/10.3390/s8117085 - 7 Nov 2008

Cited by 18 | Viewed by 13018

Abstract

A carbon nanotube/La-doped TiO₂ (La-TiO₂) nanocomposite (CLTN) was prepared by a procedure similar to a complex/adsorption process. Scanning electron microscopy (SEM) images show that the La-TiO₂ distributes on the carbon nanotube walls. The CLTN was mixed with paraffin to [...] Read more.

A carbon nanotube/La-doped TiO₂ (La-TiO₂) nanocomposite (CLTN) was prepared by a procedure similar to a complex/adsorption process. Scanning electron microscopy (SEM) images show that the La-TiO₂ distributes on the carbon nanotube walls. The CLTN was mixed with paraffin to form a CLTN paste for the CLTN paste electrode (CLTNPE). The electrochemical characteristics of CLTNPE were compared with that of conventional carbon electrodes such as the carbon paste electrode (CPE) and glass carbon electrode (GC). The CLTNPE exhibits electrochemical activity and was used to investigate the electrochemistry of nicotinic acid (NA). The modified electrode has a strong electrocatalytic effect on the redox of NA. The cyclic voltammetry (CV) redox potential of NA at the CLTNPE is 320 mV. The oxidation process of NA on the CLTNPE is pH dependent. A sensitive chronoamperometric response for NA was obtained covering a linear range from 1.0×10^-6 mol·L^-1 to 1.2×10-4 mol·L^-1, with a detection limit of 2.7×10^-7 mol·L^-1. The NA sensor displays a remarkable sensitivity and stability. The mean recovery of NA in the human urine is 101.8%, with a mean variation coefficient (RSD) of 2.6%. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Graphical abstract

300 KiB

Open AccessArticle

Modelling Amperometric Biosensors Based on Chemically Modified Electrodes

by Romas Baronas and Juozas Kulys

Sensors 2008, 8(8), 4800-4820; https://doi.org/10.3390/s8084800 - 19 Aug 2008

Cited by 23 | Viewed by 11285

Abstract

The response of an amperometric biosensor based on a chemically modified electrode was modelled numerically. A mathematical model of the biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments: an enzyme layer and an outer diffusion [...] Read more.

The response of an amperometric biosensor based on a chemically modified electrode was modelled numerically. A mathematical model of the biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments: an enzyme layer and an outer diffusion layer. In order to define the main governing parameters the corresponding dimensionless mathematical model was derived. The digital simulation was carried out using the finite difference technique. The adequacy of the model was evaluated using analytical solutions known for very specific cases of the model parameters. By changing model parameters the output results were numerically analyzed at transition and steady state conditions. The influence of the substrate and mediator concentrations as well as of the thicknesses of the enzyme and diffusion layers on the biosensor response was investigated. Calculations showed complex kinetics of the biosensor response, especially when the biosensor acts under a mixed limitation of the diffusion and the enzyme interaction with the substrate. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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409 KiB

Open AccessArticle

Comparison of Mercury Distribution Between Liver and Muscle – A Biomonitoring of Fish from Lightly and Heavily Contaminated Localities

by Marcela Havelková, Ladislav Dušek, Danka Némethová, Gorzyslaw Poleszczuk and Zdeňka Svobodová

Sensors 2008, 8(7), 4095-4109; https://doi.org/10.3390/s8074095 - 10 Jul 2008

Cited by 108 | Viewed by 12335

Abstract

Tissue samples from 1,117 fish of 25 species were collected from 1991 through 1996 at 13 locations along the River Elbe. The principal indicator species were perch (Perca fluviatilis) (n=118), chub (Leuciscus cephalus L.) (n=113) and roach (Rutilus rutilus) (n=138). Mercury (Hg) concentrations [...] Read more.

Tissue samples from 1,117 fish of 25 species were collected from 1991 through 1996 at 13 locations along the River Elbe. The principal indicator species were perch (Perca fluviatilis) (n=118), chub (Leuciscus cephalus L.) (n=113) and roach (Rutilus rutilus) (n=138). Mercury (Hg) concentrations in muscle and liver were determined by atomic absorption spectrometry. The liver/muscle index in three indicator species from heavily contaminated and lightly contaminated localities were significantly different. In fish from heavily contaminated localities, Hg was deposited preferentially in the liver (the depository for inorganic and organic forms of Hg), while in lightly contaminated areas, it was deposited preferentially in muscle. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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181 KiB

Open AccessArticle

A Determination of Metallothionein in Larvae of Freshwater Midges (Chironomus riparius) Using Brdicka Reaction

by Ivo Fabrik, Zuzana Ruferova, Klara Hilscherova, Vojtech Adam, Libuse Trnkova and Rene Kizek

Sensors 2008, 8(7), 4081-4094; https://doi.org/10.3390/s8074081 - 10 Jul 2008

Cited by 30 | Viewed by 11841

Abstract

Among wide spectrum of biomolecules induced by various stress factors low molecular mass protein called metallothionein (MT) is suitable for assessment of the heavy metal environmental pollution. The aim of this work was to determine the metallothionein and total thiols content in larvae [...] Read more.

Among wide spectrum of biomolecules induced by various stress factors low molecular mass protein called metallothionein (MT) is suitable for assessment of the heavy metal environmental pollution. The aim of this work was to determine the metallothionein and total thiols content in larvae of freshwater midges (Chironomus riparius) sampled from laboratory exposure to cadmium(II) ions and from field studies using differential pulse voltammetry Brdicka reaction. Unique electrochemical instrument, stationary electrochemical analyser Autolab coupled with autosampler, was utilized for the analysis of the samples. The detection limit for MT was evaluated as 5 nM. The larvae exposed to two doses (50 ng/g or 50 μg/g) of cadmium(II) ions for fifteen days under laboratory controlled conditions were at the end of the exposure killed, homogenized and analysed. MT content in control samples was 1.2 μM, in larvae exposed to 50 ng Cd/g it was 2.0 μM and in larvae exposed to 50 μg Cd/g 2.9 μM. Moreover at field study chironomid larvae as well as sediment samples have been collected from eight field sites with different levels of pollution by heavy. The metals content (chromium, nickel, copper, zinc, arsenic, molybdenum, cadmium, tin and lead) in the sediment and or MT content in the chironomid larvae were determined by inductively coupled plasma mass spectrometry or Brdicka reaction, respectively. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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540 KiB

Open AccessArticle

Laurate Biosensors Image Brain Neurotransmitters In Vivo: Can an Antihypertensive Medication Alter Psychostimulant Behavior?

by Patricia A. Broderick, Helen Ho, Karyn Wat and Vivek Murthy

Sensors 2008, 8(7), 4033-4061; https://doi.org/10.3390/s8074033 - 4 Jul 2008

Cited by 9 | Viewed by 13497

Abstract

Neuromolecular Imaging (NMI) with novel biosensors enables the selective detection of neurotransmitters in vivo within seconds, on line and in real time. Biosensors remain in place for continuing studies over a period of months. This biotechnological advance is based on conventional electrochemistry; the [...] Read more.

Neuromolecular Imaging (NMI) with novel biosensors enables the selective detection of neurotransmitters in vivo within seconds, on line and in real time. Biosensors remain in place for continuing studies over a period of months. This biotechnological advance is based on conventional electrochemistry; the biosensors detect neurotransmitters by electron transfer. Simply stated, biosensors adsorb electrons from each neurotransmitter at specific oxidation potentials; the current derived from electron transfer is proportional to neurotransmitter concentration. Selective electron transfer properties of these biosensors permit the imaging of neurotransmitters, metabolites and precursors. The novel BRODERICK PROBE^® biosensors we have developed, differ in formulation and detection capabilities from biosensors/electrodes used in conventional electrochemistry/ voltammetry. In these studies, NMI, specifically, the BRODERICK PROBE^® laurate biosensor images neurotransmitter signals within mesolimbic neuronal terminals, nucleus accumbens (NAc); dopamine (DA), serotonin (5-HT), homovanillic acid (HVA) and Ltryptophan (L-TP) are selectively imaged. Simultaneously, we use infrared photobeams to monitor open-field movement behaviors on line with NMI in the same animal subjects. The goals are to investigate integrated neurochemical and behavioral effects of cocaine and caffeine alone and co-administered and further, to use ketanserin to decipher receptor profiles for these psychostimulants, alone and co-administered. The rationale for selecting this medication is: ketanserin (a) is an antihypertensive and cocaine and caffeine produce hypertension and (b) acts at 5-HT_2A/2C receptors, prevalent in NAc and implicated in hypertension and cocaine addiction. Key findings are: (a) the moderate dose of caffeine simultaneously potentiates cocaine's neurochemical and behavioral responses. (b) ketanserin simultaneously inhibits cocaine-increased DA and 5-HT release in NAc and open-field behaviors and (c) ketanserin inhibits 5-HT release in NAc and open-field behaviors produced by caffeine, but, surprisingly, acts to increase DA release in NAc. Importantly, the latter effect may be a possible adverse effect of the moderate dose of caffeine in hypertensive patients. Thus, an antihypertensive medication is shown here to play a role in inhibiting brain reward possibly via antihypertensive mechanisms at DA and 5-HT receptor subtypes within DA motor neurons. An explanatory note for the results obtained, is the role likely played by the G Protein Receptor Complex (GPRC) family of proteins. Empirical evidence shows that GPRC dimers, heteromers and heterotrimers may cause cross-talk between distinct signalling cascade pathways in the actions of cocaine and caffeine. Ligand-directed functional selectivity, particularly for ketanserin, in addition to GPRCs, may also cause differential responses. The results promise new therapeutic strategies for drug addiction, brain reward and cardiovascular medicine. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Electrochemical Determination of Low Molecular Mass Thiols Content in Potatoes (Solanum tuberosum) Cultivated in the Presence of Various Sulphur Forms and Infected by Late Blight (Phytophora infestans)

by Pavel Ryant, Eva Dolezelova, Ivo Fabrik, Jiri Baloun, Vojtech Adam, Petr Babula and Rene Kizek

Sensors 2008, 8(5), 3165-3182; https://doi.org/10.3390/s8053165 - 15 May 2008

Cited by 34 | Viewed by 11509

Abstract

In the present paper potato plants were cultivated in the presence of ammonium sulphate or elemental sulphur supplementation into the soil to reveal the effects of different sulphur forms on content of nitrogen, phosphorus, potassium, calcium, magnesium and sulphur, and yield of tubers. [...] Read more.

In the present paper potato plants were cultivated in the presence of ammonium sulphate or elemental sulphur supplementation into the soil to reveal the effects of different sulphur forms on content of nitrogen, phosphorus, potassium, calcium, magnesium and sulphur, and yield of tubers. During the investigation of the influence of different sulphur forms on yield of potato tubers we did not observe significant changes. Average weight of tubers of control plants per one experimental pot was 355 g. Application of sulphur in both forms resulted in moderate potato tubers weight reduction per one experimental pot compared to control group; average value ranged from 320 to 350 g per one experimental pot. Further we treated the plants with two different supplementation of sulphur with cadmium(II) ions (4 mg of cadmium(II) acetate per kilogram of the soil). The significantly lowest cadmium content (p < 0.05) was determined in tissues of plants treated with the highest dosage of elemental sulphur (0.64 mg Cd/kg) compared to control plants (0.82 mg Cd/kg). We also aimed our attention on the cadmium content in proteins, lipids or soluble carbohydrates and ash. Application of sulphate as well as elemental sulphur resulted in significant cadmium content reduction in lipid fraction compared to control plants. In addition to this we quantified content of low molecular mass thiols in potatoes tissues. To determine the thiols content we employed differential pulse voltammetry Brdicka reaction. After twelve days of the treatment enhancing of thiols level was observed in all experimental groups regardless to applied sulphur form and its concentration. Finally we evaluated the effect of sulphur supplementation on Phytophora infestans infection of potato plants. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Assessment of Organophosphate and Carbamate Pesticide Residues in Cigarette Tobacco with a Novel Cell Biosensor

by Sophie Mavrikou, Kelly Flampouri, Georgia Moschopoulou, Olga Mangana, Alexandros Michaelides and Spiridon Kintzios

Sensors 2008, 8(4), 2818-2832; https://doi.org/10.3390/s8042818 - 23 Apr 2008

Cited by 28 | Viewed by 12934

Abstract

The conventional analysis of pesticide residues in analytical commodities, such as tobacco and tobacco products is a labor intensive procedure, since it is necessary to cover a wide range of different chemicals, using a single procedure. Standard analysis methods include extensive sample pretreatment [...] Read more.

The conventional analysis of pesticide residues in analytical commodities, such as tobacco and tobacco products is a labor intensive procedure, since it is necessary to cover a wide range of different chemicals, using a single procedure. Standard analysis methods include extensive sample pretreatment (with solvent extraction and partitioning phases) and determination by GC and HPLC to achieve the necessary selectivity and sensitivity for the different classes of compounds under detection. As a consequence, current methods of analysis provide a limited sample capacity. In the present study, we report on the development of a novel cell biosensor for detecting organophosphate and carbamate pesticide residues in tobacco. The sensor is based on neuroblastoma N2a cells and the measurement of changes of the cell membrane potential, according to the working principle of the Bioelectric Recognition Assay (BERA). The presence of pesticide residues is detected by the degree of inhibition of acetylcholine esterase (AChE). The sensor instantly responded to both the organophoshate pesticide chlorpyriphos and the carbamate carbaryl in a concentration-dependent pattern, being able to detect one part per billion (1 ppb). Additionally, tobacco leaf samples (in blended dry form) were analyzed with both the novel biosensor and conventional methods, according to a double-blind protocol. Pesticide residues in tobacco samples caused a considerable cell membrane hyperpolarization to neuroblastoma cells immobilized in the sensor, as indicated by the increase of the negative sensor potential, which was clearly distinguishable from the sensor’s response against pesticide-free control samples. The observed response was quite reproducible, with an average variation of +5,6%. Fluorescence microscopy observations showed that treatment of the cells with either chlorpyrifos or carbaryl was associated with increased [Ca²+]cyt . The novel biosensor offers fresh perspectives for ultra-rapid, sensitive and low-cost monitoring of pesticide residues in tobacco as well as other food and agricultural commodities. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Biomarkers of Contaminant Exposure in Chub (Leuciscus cephalus L.) – Biomonitoring of Major Rivers in the Czech Republic

by Marcela Havelkova, Jana Blahova, Hana Kroupova, Tomas Randak, Iveta Slatinska, Drahomira Leontovycova, Roman Grabic, Richard Pospisil and Zdenka Svobodova

Sensors 2008, 8(4), 2589-2603; https://doi.org/10.3390/s8042589 - 11 Apr 2008

Cited by 21 | Viewed by 13289

Abstract

Biochemical analysis of organisms to assess exposure to environmental contaminants is of great potential use. Biochemical markers, specifically liver enzymes of the first and the second phase of xenobiotic transformation - cytochrome P450 (CYP 450), ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST) and tripeptide reduced glutathione [...] Read more.

Biochemical analysis of organisms to assess exposure to environmental contaminants is of great potential use. Biochemical markers, specifically liver enzymes of the first and the second phase of xenobiotic transformation - cytochrome P450 (CYP 450), ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST) and tripeptide reduced glutathione (GSH) - were used to assess contamination of the aquatic environment at 12 locations near the mouths of major rivers in the Czech Republic. These rivers were the Lužnice, Otava, Sázava, Berounka, Vltava, Labe, Ohře, Svratka, Dyje, Morava and Odra. The indicator species selected was the Chub (Leuciscus cephalus L.). The highest levels of CYP 450 and EROD catalytic activity were found in livers of fish from the Labe (Obříství) (0.32±0.10 nmol mg^-1 protein and 1061.38±545.51 pmol min^-1 mg^-1 protein, respectively). The highest levels of GST catalytic activity and GSH content were found in fish from the Otava (35.39±13.35 nmol min^-1 mg^-1 protein and 4.29±2.10 nmol GSH mg^-1 protein, respectively). They were compared with levels of specific inductors of these biochemical markers in muscle. The results confirmed contamination of some river locations (Labe Obříství, Svratka). Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

An Electrochemical Detection of Metallothioneins at the Zeptomole Level in Nanolitre Volumes

by Vojtech Adam, Jiri Baloun, Ivo Fabrik, Libuse Trnkova and Rene Kizek

Sensors 2008, 8(4), 2293-2305; https://doi.org/10.3390/s8042293 - 1 Apr 2008

Cited by 74 | Viewed by 10247

Abstract

An Electrochemical Detection of Metallothioneins at the Zeptomole Level in Nanolitre VolumesWe report on improvement of the adsorptive transfer stripping technique (AdTS) coupled with the differential pulse voltammetry Brdicka reaction to determine a thiol-protein. The current technique has been unable to generate reproducible [...] Read more.

An Electrochemical Detection of Metallothioneins at the Zeptomole Level in Nanolitre VolumesWe report on improvement of the adsorptive transfer stripping technique (AdTS) coupled with the differential pulse voltammetry Brdicka reaction to determine a thiol-protein. The current technique has been unable to generate reproducible results when analyzing very low sample volumes (nanolitres). This obstacle can be overcome technically by modifying the current transfer technique including cooling step of the adsorbed analyte. We tested the technique on determination of a promising tumour disease marker protein called metallothionein (MT). The detection limit (3 S/N) of MT was evaluated as 500 zeptomoles per 500 nL (1 pM) and the quantification limit (10 S/N) as 1,500 zeptomoles per 500 nL (3 pM). Further, the improved AdTS technique was utilized to analyze blood serum samples from patients with breast cancer. Based on the results obtained it can be concluded that the improved technique can be used to detect a thiolprotein in very low sample volumes and can also prevent interferences during the washing and transferring step. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Application of DNA Hybridization Biosensor as a Screening Method for the Detection of Genetically Modified Food Components

by Mariusz Tichoniuk, Marta Ligaj and Marian Filipiak

Sensors 2008, 8(4), 2118-2135; https://doi.org/10.3390/s8042118 - 27 Mar 2008

Cited by 64 | Viewed by 14773

Abstract

An electrochemical biosensor for the detection of genetically modified food components is presented. The biosensor was based on 21-mer single-stranded oligonucleotide (ssDNA probe) specific to either 35S promoter or nos terminator, which are frequently present in transgenic DNA cassettes. ssDNA probe was covalently [...] Read more.

An electrochemical biosensor for the detection of genetically modified food components is presented. The biosensor was based on 21-mer single-stranded oligonucleotide (ssDNA probe) specific to either 35S promoter or nos terminator, which are frequently present in transgenic DNA cassettes. ssDNA probe was covalently attached by 5’-phosphate end to amino group of cysteamine self-assembled monolayer (SAM) on gold electrode surface with the use of activating reagents – water soluble 1-ethyl-3(3’- dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxy-sulfosuccinimide (NHS). The hybridization reaction on the electrode surface was detected via methylene blue (MB) presenting higher affinity to ssDNA probe than to DNA duplex. The electrode modification procedure was optimized using 19-mer oligoG and oligoC nucleotides. The biosensor enabled distinction between DNA samples isolated from soybean RoundupReady^® (RR soybean) and non-genetically modified soybean. The frequent introduction of investigated DNA sequences in other genetically modified organisms (GMOs) give a broad perspectives for analytical application of the biosensor. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Electrochemical Determination of Trace Sudan I Contamination in Chili Powder at Carbon Nanotube Modified Electrodes

by Liang Ming, Xia Xi, Tingting Chen and Jie Liu

Sensors 2008, 8(3), 1890-1900; https://doi.org/10.3390/s8031890 - 17 Mar 2008

Cited by 26 | Viewed by 11426

Abstract

We have developed a simple, convenient and inexpensive voltammetric method for determining trace Sudan I contamination in chili powder, based on the catalyzed electrochemical reduction of Sudan I at the carbon nanotube modified electrode. Under optimized conditions, the method exhibited acceptable analytical performance [...] Read more.

We have developed a simple, convenient and inexpensive voltammetric method for determining trace Sudan I contamination in chili powder, based on the catalyzed electrochemical reduction of Sudan I at the carbon nanotube modified electrode. Under optimized conditions, the method exhibited acceptable analytical performance in terms of linearity (over the concentration range 6.0×10^–7 to 7.5×10^–5 M, r = 0.9967), detection limit (2.0×10^–7 M) and reproducibility (RSD = 4.6%, n=10, for 2.0×10^–5 M Sudan I). Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

The Application of DNA-Biosensors and Differential Scanning Calorimetry to the Study of the DNA-Binding Agent Berenil

by Fabiane C. De Abreu, Francine S. De Paula, Danielle C. M. Ferreira, Valberes B. Nascimento, Julio C. D. Lopes, Alexandre M. C. Santos, Marcelo M. Santoro, Carlos E. Salas and Marília O. F. Goulart

Sensors 2008, 8(3), 1519-1538; https://doi.org/10.3390/s8031519 - 3 Mar 2008

Cited by 18 | Viewed by 13635

Abstract

The in situ DNA-damaging capacity of berenil (1) has been investigated usingan electrochemical approach employing double stranded (ds) DNA-modified glassy carbonelectrode biosensors. Electrochemical voltammetric sensing of damage caused by 1 todsDNA was monitored by the appearance of peaks diagnostic of the oxidation of [...] Read more.

The in situ DNA-damaging capacity of berenil (1) has been investigated usingan electrochemical approach employing double stranded (ds) DNA-modified glassy carbonelectrode biosensors. Electrochemical voltammetric sensing of damage caused by 1 todsDNA was monitored by the appearance of peaks diagnostic of the oxidation of guanineand adenine. When 1 was incorporated directly onto the biosensor surface, DNA damagecould be observed at concentrations of additive as low as 10 μM. In contrast, when thedsDNA-modified biosensor was exposed to 1, in acetate buffer solution, the method wasmuch less sensitive and DNA damage could be detected only in the presence of 100 μMberenil. When mixed solutions of 1 and single stranded (ss) DNA, polyguanylic acid orpolyadenylic acid were submitted to voltammetric study, the oxidation signals of therespective bases decreased in a concentration-dependent manner and the major variation ofthe adenine current peak indicated preferential binding of 1 to adenine. The electrochemical results were in close agreement with those deriving from a differentialscanning calorimetric study of the DNA-berenil complex. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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216 KiB

Open AccessArticle

Amperometric Low-Potential Detection of Malic Acid Using Single-Wall Carbon Nanotubes Based Electrodes

by Adina Arvinte, Lucian Rotariu and Camelia Bala

Sensors 2008, 8(3), 1497-1507; https://doi.org/10.3390/s8031497 - 3 Mar 2008

Cited by 25 | Viewed by 9785

Abstract

The electrocatalytical property of single-wall carbon nanotube (SWNT)modified electrode toward NADH detection was explored by cyclic voltammetry andamperometry techniques. The experimental results show that SWNT decrease theovervoltage required for oxidation of NADH (to 300 mV vs. Ag/AgCl) and this propertymake them suitable for [...] Read more.

The electrocatalytical property of single-wall carbon nanotube (SWNT)modified electrode toward NADH detection was explored by cyclic voltammetry andamperometry techniques. The experimental results show that SWNT decrease theovervoltage required for oxidation of NADH (to 300 mV vs. Ag/AgCl) and this propertymake them suitable for dehydrogenases based biosensors. The behavior of the SWNTmodified biosensor for L-malic acid was studied as an example for dehydrogenasesbiosensor. The amperometric measurements indicate that malate dehydrogenase (MDH)can be strongly adsorbed on the surface of the SWNT-modified electrode to form anapproximate monolayer film. Enzyme immobilization in Nafion membrane can increasethe biosensor stability. A linear calibration curve was obtained for L-malic acidconcentrations between 0.2 and 1mM. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Assembling Amperometric Biosensors for Clinical Diagnostics

by María Soledad Belluzo, María Elida Ribone and Claudia Marina Lagier

Sensors 2008, 8(3), 1366-1399; https://doi.org/10.3390/s8031366 - 27 Feb 2008

Cited by 108 | Viewed by 22198

Abstract

Clinical diagnosis and disease prevention routinely require the assessment ofspecies determined by chemical analysis. Biosensor technology offers several benefits overconventional diagnostic analysis. They include simplicity of use, specificity for the targetanalyte, speed to arise to a result, capability for continuous monitoring and multiplexing,together [...] Read more.

Clinical diagnosis and disease prevention routinely require the assessment ofspecies determined by chemical analysis. Biosensor technology offers several benefits overconventional diagnostic analysis. They include simplicity of use, specificity for the targetanalyte, speed to arise to a result, capability for continuous monitoring and multiplexing,together with the potentiality of coupling to low-cost, portable instrumentation. This workfocuses on the basic lines of decisions when designing electron-transfer-based biosensorsfor clinical analysis, with emphasis on the strategies currently used to improve the deviceperformance, the present status of amperometric electrodes for biomedicine, and the trendsand challenges envisaged for the near future. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Construction of a nrdA::luxCDABE Fusion and Its Use in Escherichia coli as a DNA Damage Biosensor

by Ee Taek Hwang, Joo- Myung Ahn, Byoung Chan Kim and Man Bock Gu

Sensors 2008, 8(2), 1297-1307; https://doi.org/10.3390/s8021297 - 22 Feb 2008

Cited by 18 | Viewed by 11819

Abstract

The promoter of nrdA gene which is related with DNA synthesis was used to construct a DNA damage sensitive biosensor. A recombinant bioluminescent E. coli strain, BBTNrdA, harboring a plasmid with the nrdA promoter fused to the luxCDABE operon, was successfully constructed. Its [...] Read more.

The promoter of nrdA gene which is related with DNA synthesis was used to construct a DNA damage sensitive biosensor. A recombinant bioluminescent E. coli strain, BBTNrdA, harboring a plasmid with the nrdA promoter fused to the luxCDABE operon, was successfully constructed. Its response to various chemicals including genotoxic chemicals substantiates it as a DNA damage biosensor. In characterization, three different classes of toxicants were used: DNA damaging chemicals, oxidative stress chemicals, and phenolics. BBTNrdA only responded strongly to DNA damaging chemicals, such as nalidixic acid (NDA), mitomycin C (MMC), 1-methyl-1-nitroso-N-methylguanidine (MNNG), and 4-nitroquinoline N-oxide (4-NQO). In contrast, there were no responses from the oxidative stress chemicals and phenolics, except from hydrogen peroxide (H2O2) which is known to cause DNA damage indirectly. Therefore, the results of the study demonstrate that BBTNrdA can be used as a DNA damage biosensor. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Dependence of Impedance of Embedded Single Cells on Cellular Behaviour

by Sungbo Cho, Marc Castellarnau, Josep Samitier and Hagen Thielecke

Sensors 2008, 8(2), 1198-1211; https://doi.org/10.3390/s8021198 - 21 Feb 2008

Cited by 11 | Viewed by 14465

Abstract

Non-invasive single cell analyses are increasingly required for the medicaldiagnostics of test substances or the development of drugs and therapies on the single celllevel. For the non-invasive characterisation of cells, impedance spectroscopy whichprovides the frequency dependent electrical properties has been used. Recently,microfludic systems [...] Read more.

Non-invasive single cell analyses are increasingly required for the medicaldiagnostics of test substances or the development of drugs and therapies on the single celllevel. For the non-invasive characterisation of cells, impedance spectroscopy whichprovides the frequency dependent electrical properties has been used. Recently,microfludic systems have been investigated to manipulate the single cells and tocharacterise the electrical properties of embedded cells. In this article, the impedance ofpartially embedded single cells dependent on the cellular behaviour was investigated byusing the microcapillary. An analytical equation was derived to relate the impedance ofembedded cells with respect to the morphological and physiological change ofextracellular interface. The capillary system with impedance measurement showed afeasibility to monitor the impedance change of embedded single cells caused bymorphological and physiological change of cell during the addition of DMSO. By fittingthe derived equation to the measured impedance of cell embedded at different negativepressure levels, it was able to extrapolate the equivalent gap and gap conductivity betweenthe cell and capillary wall representing the cellular behaviour. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Integrated Electrochemical Analysis System with Microfluidic and Sensing Functions

by Wataru Satoh, Hiroki Hosono, Hiroomi Yokomaku, Katsuya Morimoto, Sanjay Upadhyay and Hiroaki Suzuki

Sensors 2008, 8(2), 1111-1127; https://doi.org/10.3390/s8021111 - 21 Feb 2008

Cited by 26 | Viewed by 10062

Abstract

An integrated device that carries out the timely transport of solutions andconducts electroanalysis was constructed. The transport of solutions was based oncapillary action in overall hydrophilic flow channels and control by valves that operateon the basis of electrowetting. Electrochemical sensors including glucose, lactate,glutamic [...] Read more.

An integrated device that carries out the timely transport of solutions andconducts electroanalysis was constructed. The transport of solutions was based oncapillary action in overall hydrophilic flow channels and control by valves that operateon the basis of electrowetting. Electrochemical sensors including glucose, lactate,glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), pH,ammonia, urea, and creatinine were integrated. An air gap structure was used for theammonia, urea, and creatinine sensors to realize a rapid response. To enhance thetransport of ammonia that existed or was produced by the enzymatic reactions, the pHof the solution was elevated by mixing it with a NaOH solution using a valve based onelectrowetting. The sensors for GOT and GPT used a freeze-dried substrate matrix torealize rapid mixing. The sample solution was transported to required sensing sites atdesired times. The integrated sensors showed distinct responses when a sample solutionreached the respective sensing sites. Linear relationships were observed between theoutput signals and the concentration or the logarithm of the concentration of theanalytes. An interferent, L-ascorbic acid, could be eliminated electrochemically in thesample injection port. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Influence of Cadmium(II) Ions and Brewery Sludge on Metallothionein Level in Earthworms (Eisenia fetida) – Bio- transforming of Toxic Wastes

by Dalibor Huska, Sona Krizkova, Miroslava Beklova, Ladislav Havel, Josef Zehnalek, Vaclav Diopan, Vojtech Adam, Ladislav Zeman, Petr Babula and Rene Kizek

Sensors 2008, 8(2), 1039-1047; https://doi.org/10.3390/s8021039 - 19 Feb 2008

Cited by 18 | Viewed by 9177

Abstract

Metallothioneins belong to a group of intracellular, high molecular andcysteine-rich proteins whose content in an organism increase with increasing concentrationof a heavy metal. The aim of this work was to apply the electrochemical analysis for theanalysis of metallothioneins in earthworms exposed to cadmium [...] Read more.

Metallothioneins belong to a group of intracellular, high molecular andcysteine-rich proteins whose content in an organism increase with increasing concentrationof a heavy metal. The aim of this work was to apply the electrochemical analysis for theanalysis of metallothioneins in earthworms exposed to cadmium ions and brewery sludge.Here we utilized adsorptive transfer technique coupled with differential pulse voltammetryBrdicka reaction to determine metallothionein in different biological samples. By meansthis very sensitive technique it was possible to analyze metallothionein in concentrationsbelow 1 μmol.l^-1 with the standard deviation of 4-5%. We found out that the average MTlevel in the non-treated earthworms oscillated between 19 and 48 μmol.l^-1. When weanalysed samples of earthworms treated by cadmium, we observed that the MT contentincreased with the exposition length and increase dose of cadmium ions. Finally, weattempted to study and compare the toxicity of the raw sludge and its leach by using ofearthworms. The raw brewery sludge caused the death of the earthworms quickly.Earthworms held in the presence of leach from brewery sludge increased their weight of147 % of their original weight because they ingested the nutrients from the sludge. Themetallothionein level changes markedly with increasing time of exposition and applieddose of toxic compound. It clearly follows from the obtained results that the MT synthesisis insufficient in the first hours of the exposition and increases after more than 24 h. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Lactoferrin Isolation Using Monolithic Column Coupled with Spectrometric or Micro-Amperometric Detector

by Vojtech Adam, Ondrej Zitka, Petr Dolezal, Ladislav Zeman, Ales Horna, Jaromir Hubalek, Jan Sileny, Sona Krizkova, Libuse Trnkova and Rene Kizek

Sensors 2008, 8(1), 464-487; https://doi.org/10.3390/s8010464 - 24 Jan 2008

Cited by 37 | Viewed by 48465

Abstract

Lactoferrin is a multifunctional protein with antimicrobial activity and others tohealth beneficial properties. The main aim of this work was to propose easy to usetechnique for lactoferrin isolation from cow colostrum samples. Primarily we utilizedsodium dodecyl sulphate – polyacrylamide gel electrophoresis for isolation [...] Read more.

Lactoferrin is a multifunctional protein with antimicrobial activity and others tohealth beneficial properties. The main aim of this work was to propose easy to usetechnique for lactoferrin isolation from cow colostrum samples. Primarily we utilizedsodium dodecyl sulphate – polyacrylamide gel electrophoresis for isolation of lactoferrinfrom the real samples. Moreover we tested automated microfluidic Experionelectrophoresis system to isolate lactoferrin from the collostrum sample. The welldeveloped signal of lactoferrin was determined with detection limit (3 S/N) of 20 ng/ml. Inspite of the fact that Experion is faster than SDS-PAGE both separation techniques cannotbe used in routine analysis. Therefore we have tested third separation technique, ionexchange chromatography, using monolithic column coupled with UV-VIS detector (LCUV-VIS). We optimized wave length (280 nm), ionic strength of the elution solution (1.5M NaCl) and flow rate of the retention and elution solutions (0.25 ml/min and 0.75 ml/min.respectively). Under the optimal conditions the detection limit was estimated as 0.1 μg/mlof lactoferrin measured. Using LC-UV-VIS we determined that lactoferrin concentrationvaried from 0.5 g/l to 1.1 g/l in cow colostrums collected in the certain time interval up to 72 hours after birth. Further we focused on miniaturization of detection device. We testedamperometric detection at carbon electrode. The results encouraged us to attempt tominiaturise whole detection system and to test it on analysis of real samples of humanfaeces, because lactoferrin level in faeces is closely associated with the inflammations ofintestine mucous membrane. For the purpose of miniaturization we employed thetechnology of printed electrodes. The detection limit of lactoferrin was estimated as 10μg/ml measured by the screen-printed electrodes fabricated by us. The fabricatedelectrodes were compared with commercially available ones. It follows from the obtainedresults that the responses measured by commercial electrodes are app. ten times highercompared with those measured by the electrodes fabricated by us. This phenomenonrelates with smaller working electrode surface area of the electrodes fabricated by us(about 50 %) compared to the commercial ones. The screen-printed electrodes fabricatedby us were utilized for determination of lactoferrin faeces. Regarding to fact that sample offaeces was obtained from young and healthy man the amount of lactoferrin in sample wasunder the limit of detection of this method. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Multi-instrumental Analysis of Tissues of Sunflower Plants Treated with Silver(I) Ions – Plants as Bioindicators of Environmental Pollution

by Sona Krizkova, Pavel Ryant, Olga Krystofova, Vojtech Adam, Michaela Galiova, Miroslava Beklova, Petr Babula, Jozef Kaiser, Karel Novotny, Jan Novotny, Miroslav Liska, Radomir Malina, Josef Zehnalek, Jaromir Hubalek, Ladislav Havel and Rene Kizek

Sensors 2008, 8(1), 445-463; https://doi.org/10.3390/s8010445 - 24 Jan 2008

Cited by 83 | Viewed by 25443

Abstract

The aim of this work is to investigate sunflower plants response on stressinduced by silver(I) ions. The sunflower plants were exposed to silver(I) ions (0, 0.1, 0.5,and 1 mM) for 96 h. Primarily we aimed our attention to observation of basic physiologicalparameters. We [...] Read more.

The aim of this work is to investigate sunflower plants response on stressinduced by silver(I) ions. The sunflower plants were exposed to silver(I) ions (0, 0.1, 0.5,and 1 mM) for 96 h. Primarily we aimed our attention to observation of basic physiologicalparameters. We found that the treated plants embodied growth depression, coloured changes and lack root hairs. Using of autofluorescence of anatomical structures, such aslignified cell walls, it was possible to determine the changes of important shoot and rootstructures, mainly vascular bungles and development of secondary thickening. Thedifferences in vascular bundles organisation, parenchymatic pith development in the rootcentre and the reduction of phloem part of vascular bundles were well observable.Moreover with increasing silver(I) ions concentration the vitality of rhizodermal cellsdeclined; rhizodermal cells early necrosed and were replaced by the cells of exodermis.Further we employed laser induced breakdown spectroscopy for determination of spatialdistribution of silver(I) ions in tissues of the treated plants. The Ag is accumulated mainlyin near-root part of the sample. Moreover basic biochemical indicators of environmentalstress were investigated. The total content of proteins expressively decreased withincreasing silver(I) ions dose and the time of the treatment. As we compare the resultsobtained by protein analysis – the total protein contents in shoot as well as root parts – wecan assume on the transport of the proteins from the roots to shoots. This phenomenon canbe related with the cascade of processes connecting with photosynthesis. The secondbiochemical parameter, which we investigated, was urease activity. If we compared theactivity in treated plants with control, we found out that presence of silver(I) ions markedlyenhanced the activity of urease at all applied doses of this toxic metal. Finally we studiedthe effect of silver(I) ions on activity of urease in in vitro conditions. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Study of Copper and Purine-Copper Complexes on Modified Carbon Electrodes by Cyclic and Elimination Voltammetry

by Libuse Trnkova, Lenka Zerzankova, Filip Dycka, Radka Mikelova and Frantisek Jelen

Sensors 2008, 8(1), 429-444; https://doi.org/10.3390/s8010429 - 24 Jan 2008

Cited by 29 | Viewed by 11413

Abstract

Using a paraffin impregnated graphite electrode (PIGE) and mercury-modifiedpyrolytic graphite electrode with basal orientation (Hg-PGEb) copper(II) and Cu(II)-DNApurine base solutions have been studied by cyclic (CV) and linear sweep voltammetry(LSV) in connection with elimination voltammetry with linear scan (EVLS). In chlorideand bromide solutions [...] Read more.

Using a paraffin impregnated graphite electrode (PIGE) and mercury-modifiedpyrolytic graphite electrode with basal orientation (Hg-PGEb) copper(II) and Cu(II)-DNApurine base solutions have been studied by cyclic (CV) and linear sweep voltammetry(LSV) in connection with elimination voltammetry with linear scan (EVLS). In chlorideand bromide solutions (pH 6), the redox process of Cu(II) proceeded on PIGE with twocathodic and two anodic potentially separated signals. According to the eliminationfunction E4, the first cathodic peak corresponds to the reduction Cu(II) e^- → Cu(I) withthe possibility of fast disproportionation 2Cu(I) → Cu(II) Cu(0). The E4 of the secondcathodic peak signalized an electrode process controlled by a surface reaction. Theelectrode system of Cu(II) on Hg-PGEb in borate buffer (pH 9.2) was characterized by onecathodic and one anodic peak. Anodic stripping voltammetry (ASV) on PIGE and cathodicstripping voltammetry (CSV) on Hg-PGEb were carried out at potentials where thereduction of copper ions took place and Cu(I)-purine complexes were formed. By usingASV and CSV in combination with EVLS, the sensitivity of Cu(I)-purine complexdetection was enhanced relative to either ASV or CSV alone, resulting in higher peakcurrents of more than one order of magnitude. The statistical treatment of CE data wasused to determine the reproducibility of measurements. Our results show that EVLS inconnection with the stripping procedure is useful for both qualitative and quantitativemicroanalysis of purine derivatives and can also reveal details of studied electrodeprocesses. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Enzyme-Linked Electrochemical Detection of PCR-Amplified Nucleotide Sequences Using Disposable Screen-Printed Sensors. Applications in Gene Expression Monitoring

by Petra Horaková-Brazdilova, Miloslava Fojtova, Karel Vytras and Miroslav Fojta

Sensors 2008, 8(1), 193-210; https://doi.org/10.3390/s8010193 - 21 Jan 2008

Cited by 22 | Viewed by 10902

Abstract

Electrochemical enzyme-linked techniques for sequence-specific DNA sensingare presented. These techniques are based on attachment of streptavidin-alkalinephosphatase conjugate to biotin tags tethered to DNA immobilized at the surface ofdisposable screen-printed carbon electrodes (SPCE), followed by production andelectrochemical determination of an electroactive indicator, 1-naphthol. Via [...] Read more.

Electrochemical enzyme-linked techniques for sequence-specific DNA sensingare presented. These techniques are based on attachment of streptavidin-alkalinephosphatase conjugate to biotin tags tethered to DNA immobilized at the surface ofdisposable screen-printed carbon electrodes (SPCE), followed by production andelectrochemical determination of an electroactive indicator, 1-naphthol. Via hybridizationof SPCE surface-confined target DNAs with end-biotinylated probes, highly specificdiscrimination between complementary and non-complementary nucleotide sequences wasachieved. The enzyme-linked DNA hybridization assay has been successfully applied inanalysis of PCR-amplified real genomic DNA sequences, as well as in monitoring of planttissue-specific gene expression. In addition, we present an alternative approach involvingsequence-specific incorporation of biotin-labeled nucleotides into DNA by primerextension. Introduction of multiple biotin tags per probe primer resulted in considerableenhancement of the signal intensity and improvement of the specificity of detection. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Gold Nanoparticles With Special Shapes: Controlled Synthesis, Surface-enhanced Raman Scattering, and The Application in Biodetection

by Jianqiang Hu, Zhouping Wang and Jinghong Li

Sensors 2007, 7(12), 3299-3311; https://doi.org/10.3390/s7123299 - 14 Dec 2007

Cited by 170 | Viewed by 14283

Abstract

Specially shaped gold nanoparticles have intrigued considerable attention becausethey usually possess high-sensitivity surface-enhanced Raman scattering (SERS) and thusresult in large advantages in trace biodetermination. In this article, starch-capped goldnanoparticles with hexagon and boot shapes were prepared through using a nontoxic andbiologically benign aqueous-phase [...] Read more.

Specially shaped gold nanoparticles have intrigued considerable attention becausethey usually possess high-sensitivity surface-enhanced Raman scattering (SERS) and thusresult in large advantages in trace biodetermination. In this article, starch-capped goldnanoparticles with hexagon and boot shapes were prepared through using a nontoxic andbiologically benign aqueous-phase synthetic route. Shape effects of gold nanoparticles onSERS properties were mainly investigated, and found that different-shaped goldnanoparticles possess different SERS properties. Especially, the boot-shaped nanoparticlescould induce more 100-fold SERS enhancements in sensitivity as compared with those fromgold nanospheres. The extremely strong SERS properties of gold nanoboots have beensuccessfully applied to the detection of avidin. The unique nanoboots with high-sensitivitySERS properties are also expected to find use in many other fields such as biolabel,bioassay, biodiagnosis, and even clinical diagnosis and therapy. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Non-Destructive Evaluation of Historical Paper Based on pH Estimation from VOC Emissions

by Matija Strlič, Irena Kralj Cigić, Jana Kolar, Gerrit De Bruin and Boris Pihlar

Sensors 2007, 7(12), 3136-3145; https://doi.org/10.3390/s7123136 - 5 Dec 2007

Cited by 65 | Viewed by 11637

Abstract

Volatile organic compounds (VOCs) emitted from materials during degradationcan be a valuable source of information. In this work, the emissions of furfural and aceticacid from cellulose were studied using solid-phase micro-extraction (SPME) incombination with gas chromatography-mass spectrometry. Two sampling techniques wereemployed: static headspace [...] Read more.

Volatile organic compounds (VOCs) emitted from materials during degradationcan be a valuable source of information. In this work, the emissions of furfural and aceticacid from cellulose were studied using solid-phase micro-extraction (SPME) incombination with gas chromatography-mass spectrometry. Two sampling techniques wereemployed: static headspace sampling using SPME for 1 h at 40 ^oC after 18-h samplepreparation at 80 ^oC in a closed glass vial, and contact SPME in a stack of paper (or abook). While a number of VOCs are emitted from paper under conditions of natural oraccelerated degradation, two compounds were confirmed to be of particular diagnosticvalue: acetic acid and furfural. The emissions of furfural are shown to correlate with pH ofthe cellulosic environment. Since pH is one of the most important parameters regardingdurability of this material, the developed method could be used for non-destructiveevaluation of historical paper. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Piezoelectric Biosensor for a Simple Serological Diagnosis of Tularemia in Infected European Brown Hares (Lepus europaeus)

by Miroslav Pohanka, František Treml, Martin Hubálek, Hana Banďouchová, Miroslava Beklová and Jiří Pikula

Sensors 2007, 7(11), 2825-2834; https://doi.org/10.3390/s7112825 - 19 Nov 2007

Cited by 20 | Viewed by 9675

Abstract

Piezoelectric biosensor was used for diagnosis of infection by Francisellatularensis subsp. holarctica in European brown hares. Two kinds of experiments wereperformed in this study. First, sera from experimentally infected European brown hares(Lepus europaeus) were assayed by piezoelectric biosensor and the seventh day postinfection [...] Read more.

Piezoelectric biosensor was used for diagnosis of infection by Francisellatularensis subsp. holarctica in European brown hares. Two kinds of experiments wereperformed in this study. First, sera from experimentally infected European brown hares(Lepus europaeus) were assayed by piezoelectric biosensor and the seventh day postinfection was found as the first one when statistically significant diagnosis of tularemia waspossible; all other sera collected from hares later than on day 7 following the infection werefound tularemia positive. Typing to classify the field strain of F. tularensis used for theexperimental infection was confirmed by proteome study. Second, sera from 35 Europeanbrown hare specimens sampled at hunting grounds and tested as tularemia positive by slowagglutination allowed diagnosis of tularemia by the piezoelectric biosensor. All these sera ofnaturally infected hares were found as tularemia positive, too. Efficacy of the piezoelectricbiosensor for the serological diagnosis of tularemia is discussed. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Electrochemical Interrogation of Interactions between Surface-Confined DNA and Methylene Blue

by Dun Pan, Xiaolei Zuo, Ying Wan, Lihua Wang, Jiong Zhang, Shiping Song and Chunhai Fan

Sensors 2007, 7(11), 2671-2680; https://doi.org/10.3390/s7112671 - 12 Nov 2007

Cited by 71 | Viewed by 12018

Abstract

In this work, we reported a systematic investigation on the interactions betweenmethylene blue (MB) and surface-confined DNA by using electrochemical methods. Wedemonstrated that the redox potential of MB and binding and dissociation kinetics of MB toDNA differed significantly for single-stranded DNA (ss-DNA) and [...] Read more.

In this work, we reported a systematic investigation on the interactions betweenmethylene blue (MB) and surface-confined DNA by using electrochemical methods. Wedemonstrated that the redox potential of MB and binding and dissociation kinetics of MB toDNA differed significantly for single-stranded DNA (ss-DNA) and double-stranded DNA(ds-DNA) immobilized on gold electrodes. This was possibly due to the different bindingmechanism between MB and ss- or ds-DNA. This work might provide useful informationfor developing MB-based sequence-specific electrochemical DNA sensors. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Biochemical Markers for Assessing Aquatic Contamination

by Marcela Havelková, Tomáš Randák, Vladimír Žlábek, Jan Krijt, Hana Kroupová, Jana Pulkrabová and Zdeňka Svobodová

Sensors 2007, 7(11), 2599-2611; https://doi.org/10.3390/s7112599 - 2 Nov 2007

Cited by 32 | Viewed by 11226

Abstract

Biochemical markers, specifically enzymes of the first phase of xenobiotic transformation - cytochrome P450 and ethoxyresorufin-O-deethylase (EROD) - were used to determine the quantities of persistent organic pollutants (POPs) in fish muscle (PCB, HCB, HCH, OCS, DDT). Eight rivers were monitored (Orlice, Chrudimka, [...] Read more.

Biochemical markers, specifically enzymes of the first phase of xenobiotic transformation - cytochrome P450 and ethoxyresorufin-O-deethylase (EROD) - were used to determine the quantities of persistent organic pollutants (POPs) in fish muscle (PCB, HCB, HCH, OCS, DDT). Eight rivers were monitored (Orlice, Chrudimka, Cidlina, Jizera, Vltava, Ohře and Bílina; and the River Blanice was used as a control). The indicator species selected was the chub (Leuciscus cephalus L.). There were no significant differences in cytochrome P450 content between the locations monitored. The highest concentration of cytochrome P450 in fish liver was in the Vltava (0.241 nmol mg-1 protein), and the lowest was in the Orlice (0.120 nmol mg-1 protein). Analysis of EROD activity showed a significant difference between the Blanice and the Vltava (P< 0.05), and also between the Orlice and the Vltava (P< 0.01), the Orlice and the Bílina (P< 0.01), and the Orlice and the Ohře (P< 0.05). The highest EROD activity in fish liver was in the Vltava (576.4 pmol min-1 mg-1 protein), and the lowest was in the Orlice (63.05 pmol min-1 mg-1 protein). In individual locations, results of chemical monitoring and values of biochemical markers were compared. A significant correlation (P< 0.05) was found between biochemical markers and OCS, and PCB. Among the tributaries studied those that contaminated the Elbe most were the Vltava and the Bílina. These tributaries should not be considered the main sources of industrial contamination of the River Elbe, because the most important contamination sources were along the river Elbe itself. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Shapes of Differential Pulse Voltammograms and Level of Metallothionein at Different Animal Species

by Vojtech Adam, Miroslava Beklova, Jiri Pikula, Jaromir Hubalek, Libuse Trnkova and Rene Kizek

Sensors 2007, 7(10), 2419-2429; https://doi.org/10.3390/s7102419 - 19 Oct 2007

Cited by 27 | Viewed by 9942

Abstract

Metallothioneins play a key role in maintaining homeostasis of essential metalsand in protecting of cells against metal toxicity as well as oxidative damaging. Exceptinghumans, blood levels of metallothionein have not yet been reported from any animalspecies. Blood plasma samples of 9 animal species [...] Read more.

Metallothioneins play a key role in maintaining homeostasis of essential metalsand in protecting of cells against metal toxicity as well as oxidative damaging. Exceptinghumans, blood levels of metallothionein have not yet been reported from any animalspecies. Blood plasma samples of 9 animal species were analysed by the adsorptive transferstripping technique to obtain species specific voltammograms. Quite distinct records wereobtained from the Takin (Budorcas taxicolor), while other interesting records were observedin samples from the European Bison (Bison bonasus bonasus) and the Red-eared Slider(Trachemys scripta elegans). To quantify metallothionein the catalytic peak Cat2 was used,well developed in the Domestic Fowl (Gallus gallus f. domestica) and showing a very lowsignal in the Red Deer (Cervus elaphus). The highest levels of metallothionein reachingover 20 μM were found in the Domestic Fowl. High levels of MT were also found in theBearded Dragon (Pogona vitticeps) and the Grey Wolf (Canis lupus lupus). The lowestvalues of about 1-3 μM were determined in the Red-eared Slider, Takin and Red Deer. Employing a simple electrochemical detection it was possible to examine variation in blood metallothionein in different species of vertebrates. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Utilizing of Square Wave Voltammetry to Detect Flavonoids in the Presence of Human Urine

by Vojtech Adam, Radka Mikelova, Jaromír Hubalek, Pavel Hanustiak, Miroslava Beklova, Petr Hodek, Ales Horna, Libuse Trnkova, Marie Stiborova, Ladislav Zeman and Rene Kizek

Sensors 2007, 7(10), 2402-2418; https://doi.org/10.3390/s7102402 - 19 Oct 2007

Cited by 60 | Viewed by 14600

Abstract

About biological affecting of flavonoids on animal organisms is known less,thus we selected flavonoids, flavanones and flavones, and their glycosides, which wereexamined as potential inducers of cytochrome(s) P450 when administrated by gavages intoexperimental male rats. The study was focused on induction of CYP1A1, [...] Read more.

About biological affecting of flavonoids on animal organisms is known less,thus we selected flavonoids, flavanones and flavones, and their glycosides, which wereexamined as potential inducers of cytochrome(s) P450 when administrated by gavages intoexperimental male rats. The study was focused on induction of CYP1A1, the majorcytochrome P450 involved in carcinogen activation. The data obtained demonstrate thenecessity of taking into account not only ability of flavonoids to bind to Ah receptor(induction factor) but also to concentrate on their distribution and metabolism (includingcolon microflora) in the body. After that we examined certain flavonoids as potential inducers of cytochrome P450, we wanted to suggest and optimize suitable electrochemical technique for determination of selected flavonoids (quercetin, quercitrin, rutin, chrysin and diosmin) in body liquids. For these purposes, we selected square wave voltannetry using carbon paste electrode. Primarily we aimed on investigation of their basic electrochemical behaviour. After that we have optimized frequency, step potential and supporting electrolyte. Based on the results obtained, we selected the most suitable conditions for determination of the flavonoids as follows: frequency 180 Hz, step potential 1.95 mV/s and phosphate buffer of pH 7 as supporting electrolyte. Detection limits (3 S/N) of the flavonoids were from units to tens of nM except diosmin, where the limit were higher than μM. In addition, we attempted to suggest a sensor for analysis of flavonoids in urine. It clearly follows from the results obtained that flavonoids can be analysed in the presence of animal urine, because urine did not influence much the signals of flavonoids (recoveries of the signals were about 90 %). Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Hazards of Secondary Bromadiolone Intoxications Evaluated using High-performance Liquid Chromatography with Electrochemical Detection

by Sona Krizkova, Miroslava Beklova, Jiri Pikula, Vojtech Adam, Ales Horna and René Kizek

Sensors 2007, 7(7), 1271-1286; https://doi.org/10.3390/s7071271 - 20 Jul 2007

Cited by 18 | Viewed by 13144

Abstract

This study reported on the possibility of intoxications of non-target wild animalsassociated with use of bromadiolone as the active component of rodenticides withanticoagulation effects. A laboratory test was done with earthworms were exposed tobromadiolone-containing granules under the conditions specified in the modified OECD207 [...] Read more.

This study reported on the possibility of intoxications of non-target wild animalsassociated with use of bromadiolone as the active component of rodenticides withanticoagulation effects. A laboratory test was done with earthworms were exposed tobromadiolone-containing granules under the conditions specified in the modified OECD207 guideline. No mortality of earthworms was observed during the fourteen days longexposure. When the earthworms from the above test became a part of the diet of commonvoles in the following experiment, no mortality of consumers was observed too. However,electrochemical analysis revealed higher levels of bromadiolone in tissues fromearthworms as well as common voles compared to control animals. There were determinedcomparable levels of bromadiolone in the liver tissue of common voles after primary(2.34±0.10 μg/g) and secondary (2.20±0.53 μg/g) intoxication. Therefore, the risk ofsecondary intoxication of small mammalian species feeding on bromadiolone-containing earthworms is the same as of primary intoxication through baited granules. Bromadiolone bio-accumulation in the food chain was monitored using the newly developed analytical procedure based on the use of a liquid chromatography coupled with electrochemical detector (HPLC-ED). The HPLC-ED method allowed to determine the levels of bromadiolone in biological samples and is therefore suitable for examining the environmental hazards of this substance. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

An Investigation of Glutathione-Platinum(II) Interactions by Means of the Flow Injection Analysis Using Glassy Carbon Electrode

by Ondrej Zitka, Dalibor Huska, Sona Krizkova, Vojtech Adam, Grace J. Chavis, Libuse Trnkova, Ales Horna, Jaromir Hubalek and Rene Kizek

Sensors 2007, 7(7), 1256-1270; https://doi.org/10.3390/s7071256 - 20 Jul 2007

Cited by 28 | Viewed by 12825

Abstract

Despite very intensive research in the synthesising of new cytostatics, cisplatin isstill one of the most commonly used anticancer drugs. Therefore, an investigation ofinteractions of cisplatin with different biologically important amino acids, peptides andproteins is very topical. In the present paper, we utilized [...] Read more.

Despite very intensive research in the synthesising of new cytostatics, cisplatin isstill one of the most commonly used anticancer drugs. Therefore, an investigation ofinteractions of cisplatin with different biologically important amino acids, peptides andproteins is very topical. In the present paper, we utilized flow injection analysis coupledwith electrochemical detection to study and characterize the behaviour of various forms ofglutathione (reduced glutathione – GSH, oxidized glutathione – GSSG and S-nitrosoglutathione – GSNO). The optimized conditions were as follows: mobile phase consistedof acetate buffer (pH 3) with a flow rate of 1 mL min-1. Based on results obtained we chose850 mV as the optimal potential for detection of GSH and 1,100 mV as the optimalpotential for detection of GSSG and GSNO. The detection limits of GSH, GSSG andGSNO were 100 pg mL^-1, 50 ng mL^-1 and 300 pg mL^-1, respectively. Further, the optimized technique was used for investigation of interactions between cisplatin and GSH. We were able to observe the interaction between GSH and cisplatin via decrease in the signal corresponding to glutathione. Moreover, we evaluated the formation of the complex by spectrometry. The spectrometric results obtained were in good agreement with electrochemical ones. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Open AccessArticle

Spectrometric and Voltammetric Analysis of Urease – Nickel Nanoelectrode as an Electrochemical Sensor

by Jaromir Hubalek, Jan Hradecky, Vojtech Adam, Olga Krystofova, Dalibor Huska, Michal Masarik, Libuse Trnkova, Ales Horna, Katerina Klosova, Martin Adamek, Josef Zehnalek and Rene Kizek

Sensors 2007, 7(7), 1238-1255; https://doi.org/10.3390/s7071238 - 16 Jul 2007

Cited by 53 | Viewed by 15809

Abstract

Urease is the enzyme catalyzing the hydrolysis of urea into carbon dioxide andammonia. This enzyme is substrate-specific, which means that the enzyme catalyzes thehydrolysis of urea only. This feature is a basic diagnostic criterion used in thedetermination of many bacteria species. Most of [...] Read more.

Urease is the enzyme catalyzing the hydrolysis of urea into carbon dioxide andammonia. This enzyme is substrate-specific, which means that the enzyme catalyzes thehydrolysis of urea only. This feature is a basic diagnostic criterion used in thedetermination of many bacteria species. Most of the methods utilized for detection ofurease are based on analysis of its enzyme activity – the hydrolysis of urea. The aim of thiswork was to detect urease indirectly by spectrometric method and directly by voltammetricmethods. As spectrometric method we used is called indophenol assay. The sensitivity ofdetection itself is not sufficient to analyse the samples without pre-concentration steps.Therefore we utilized adsorptive transfer stripping technique coupled with differential pulse voltammetry to detect urease. The influence of accumulation time, pH of supporting electrolyte and concentration of urease on the enzyme peak height was investigated. Under the optimized experimental conditions (0.2 M acetate buffer pH 4.6 and accumulation time of 120 s) the detection limit of urease evaluated as 3 S/N was 200 ng/ml. The activity of urease enzyme depends on the presence of nickel. Thus the influence of nickel(II) ions on electrochemical response of the enzyme was studied. Based on the results obtained the interaction of nickel(II) ions and urease can be determined using electrochemical methods. Therefore we prepared Ni nanoelectrodes to measure urease. The Ni nanoelectrodes was analysed after the template dissolution by scanning electron microscopy. The results shown vertically aligned Ni nanopillars almost covered the electrode surface, whereas the defect places are minor and insignificant in comparison with total electrode surface. We were able to not only detect urease itself but also to distinguish its native and denatured form. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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595 KiB

Open AccessArticle

Electroanalysis of Plant Thiols

by Veronika Supalkova, Dalibor Huska, Vaclav Diopan, Pavel Hanustiak, Ondrej Zitka, Karel Stejskal, Jiri Baloun, Jiri Pikula, Ladislav Havel, Josef Zehnalek, Vojtech Adam, Libuse Trnkova, Miroslava Beklova and Rene Kizek

Sensors 2007, 7(6), 932-959; https://doi.org/10.3390/s7060932 - 13 Jun 2007

Cited by 84 | Viewed by 13601

Abstract

Due to unique physico-chemical properties of –SH moiety thiols comprise widegroup of biologically important compounds. A review devoted to biological functions ofglutathione and phytochelatins with literature survey of methods used to analysis of thesecompounds and their interactions with cadmium(II) ions and Murashige-Skoog medium [...] Read more.

Due to unique physico-chemical properties of –SH moiety thiols comprise widegroup of biologically important compounds. A review devoted to biological functions ofglutathione and phytochelatins with literature survey of methods used to analysis of thesecompounds and their interactions with cadmium(II) ions and Murashige-Skoog medium ispresented. For these purposes electrochemical techniques are used. Moreover, we revealedthe effect of three different cadmium concentrations (0, 10 and 100 μM) on cadmiumuptake and thiols content in maize plants during 192 hours long experiments usingdifferential pulse anodic stripping voltammetry to detect cadmium(II) ions and highperformance liquid chromatography with electrochemical detection to determineglutathione. Cadmium concentration determined in tissues of the plants cultivated innutrient solution containing 10 μM Cd was very low up to 96 hours long exposition andthen the concentration of Cd markedly increased. On the contrary, the addition of 100 μMCd caused an immediate sharp increase in all maize plant parts to 96 hours Cd expositionbut subsequently the Cd concentration increased more slowly. A high performance liquidchromatography with electrochemical detection was used for glutathione determination intreated maize plants after 96 and 192 hours of treatment. The highest total content of glutathione per one plant was 6 μg (96 h, 10 μM Cd) in comparison with non-treated plant (control) where glutathione content was 1.5 μg. It can be concluded that electrochemical techniques have proved to be useful to analyse plant thiols. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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537 KiB

Open AccessArticle

Multi-instrumental Investigation of Affecting of Early Somatic Embryos of Spruce by Cadmium(II) and Lead(II) Ions

by Veronika Supalkova, Jiri Petrek, Jiri Baloun, Vojtech Adam, Karel Bartusek, Libuse Trnkova, Miroslava Beklova, Vaclav Diopan, Ladislav Havel and René Kizek

Sensors 2007, 7(5), 743-759; https://doi.org/10.3390/s7050743 - 31 May 2007

Cited by 56 | Viewed by 10887

Abstract

The main aim of this work was to use multi-instrumental analytical apparatus toinvestigate the effects of treatment with cadmium(II) and/or lead(II) ions (50, 250 and 500μM) for twelve days on early somatic spruce embryos (ESEs). Primarily we used imageanalysis for estimation of growth [...] Read more.

The main aim of this work was to use multi-instrumental analytical apparatus toinvestigate the effects of treatment with cadmium(II) and/or lead(II) ions (50, 250 and 500μM) for twelve days on early somatic spruce embryos (ESEs). Primarily we used imageanalysis for estimation of growth and a fluorimetric sensor for enzymatic detection ofviability of the treated ESEs. It follows from the obtained results that Cd caused highertoxicity to ESEs than Pb. Besides this fundamental finding, we observed that ESEs grewand developed better in the presence of 500 μM of the metal ions than in the presence of250 μM. Based on the results obtained using nuclear magnetic resonance this phenomenonwas related to an increase of the area of ESE clusters by intensive uptake of water from thecultivation medium, due to dilution of the heavy metal concentration inside the cluster. Inaddition we studied the glutathione content in treated ESEs by the adsorptive transferstripping technique coupled with the differential pulse voltammetry Brdicka reaction. GSHcontents increased up to 148 ng/mg (clone 2/32) and 158 ng/mg (clone PE 14) after twelve day long treatment with Cd-EDTA ions. The GSH content was about 150 and 160 % higher in comparison with the ESEs treated with Pb-EDTA ions, respectively. The difference between GSH contents determined in ESEs treated with Pb-EDTA and Cd-EDTA ions correlates with the higher toxicity of cadmium(II) ions. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Review

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367 KiB

Open AccessReview

Electrochemical Sensors for Clinic Analysis

by You Wang, Hui Xu, Jianming Zhang and Guang Li

Sensors 2008, 8(4), 2043-2081; https://doi.org/10.3390/s8042043 - 27 Mar 2008

Cited by 299 | Viewed by 29857

Abstract

Demanded by modern medical diagnosis, advances in microfabrication technology have led to the development of fast, sensitive and selective electrochemical sensors for clinic analysis. This review addresses the principles behind electrochemical sensor design and fabrication, and introduces recent progress in the application of [...] Read more.

Demanded by modern medical diagnosis, advances in microfabrication technology have led to the development of fast, sensitive and selective electrochemical sensors for clinic analysis. This review addresses the principles behind electrochemical sensor design and fabrication, and introduces recent progress in the application of electrochemical sensors to analysis of clinical chemicals such as blood gases, electrolytes, metabolites, DNA and antibodies, including basic and applied research. Miniaturized commercial electrochemical biosensors will form the basis of inexpensive and easy to use devices for acquiring chemical information to bring sophisticated analytical capabilities to the non-specialist and general public alike in the future. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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88 KiB

Open AccessReview

Sensitive Detection of Haloperidol and Hydroxyzine at Multi-Walled Carbon Nanotubes-Modified Glassy Carbon Electrodes

by Fei Huang, Youyuan Peng, Guiying Jin, Song Zhang and Jilie Kong

Sensors 2008, 8(3), 1879-1889; https://doi.org/10.3390/s8031879 - 17 Mar 2008

Cited by 39 | Viewed by 11446

Abstract

Haloperidol (i.e. HPD) and hydroxyzine (i.e. HXY), two effective and important tranquilizers with low redox activity, were found to generate an irreversible anodic peak at about +0.86 V (vs. SCE) or two anodic peaks at about +0.83 and +0.91 V in 0.05 M [...] Read more.

Haloperidol (i.e. HPD) and hydroxyzine (i.e. HXY), two effective and important tranquilizers with low redox activity, were found to generate an irreversible anodic peak at about +0.86 V (vs. SCE) or two anodic peaks at about +0.83 and +0.91 V in 0.05 M NaH₂PO₄-Na₂HPO₄ (pH=7.0) buffer solution with a multi-walled carbon nanotubes-modified glassy carbon electrode (i.e. MWNTs/GC), respectively. Their sensitive and quantitative measurement based on the first two anodic peaks was established under the optimum conditions. The anodic peak current was linear to HPD and HXY concentration from 1×10^-7 to 2.5 ×10^-5 M and 5×10^-8 to 2.5 ×10^-5 M, the detection limits obtained were 8×10^-9 and 5×10^-9 M, separately. The modified electrode exhibited some excellent characteristics including easy regeneration, high stability, good reproducibility and selectivity. The method proposed was successfully applied to the detection of HPD and HXY in drug tablets and proved to be reliable compared with ultraviolet spectrophotometry. The modified electrode was characterized by electrochemical methods. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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5931 KiB

Open AccessReview

Electrochemical Biosensors - Sensor Principles and Architectures

by Dorothee Grieshaber, Robert MacKenzie, Janos Vörös and Erik Reimhult

Sensors 2008, 8(3), 1400-1458; https://doi.org/10.3390/s80314000 - 7 Mar 2008

Cited by 1126 | Viewed by 89276

Abstract

Quantification of biological or biochemical processes are of utmost importance for medical, biological and biotechnological applications. However, converting the biological information to an easily processed electronic signal is challenging due to the complexity of connecting an electronic device directly to a biological environment. [...] Read more.

Quantification of biological or biochemical processes are of utmost importance for medical, biological and biotechnological applications. However, converting the biological information to an easily processed electronic signal is challenging due to the complexity of connecting an electronic device directly to a biological environment. Electrochemical biosensors provide an attractive means to analyze the content of a biological sample due to the direct conversion of a biological event to an electronic signal. Over the past decades several sensing concepts and related devices have been developed. In this review, the most common traditional techniques, such as cyclic voltammetry, chronoamperometry, chronopotentiometry, impedance spectroscopy, and various field-effect transistor based methods are presented along with selected promising novel approaches, such as nanowire or magnetic nanoparticle-based biosensing. Additional measurement techniques, which have been shown useful in combination with electrochemical detection, are also summarized, such as the electrochemical versions of surface plasmon resonance, optical waveguide lightmode spectroscopy, ellipsometry, quartz crystal microbalance, and scanning probe microscopy. The signal transduction and the general performance of electrochemical sensors are often determined by the surface architectures that connect the sensing element to the biological sample at the nanometer scale. The most common surface modification techniques, the various electrochemical transduction mechanisms, and the choice of the recognition receptor molecules all influence the ultimate sensitivity of the sensor. New nanotechnology-based approaches, such as the use of engineered ion-channels in lipid bilayers, the encapsulation of enzymes into vesicles, polymersomes, or polyelectrolyte capsules provide additional possibilities for signal amplification. In particular, this review highlights the importance of the precise control over the delicate interplay between surface nano-architectures, surface functionalization and the chosen sensor transducer principle, as well as the usefulness of complementary characterization tools to interpret and to optimize the sensor response. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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745 KiB

Open AccessReview

A Review on the Electrochemical Sensors and Biosensors Composed of Nanowires as Sensing Material

by Umasankar Yogeswaran and Shen-Ming Chen

Sensors 2008, 8(1), 290-313; https://doi.org/10.3390/s8010290 - 21 Jan 2008

Cited by 439 | Viewed by 32033

Abstract

The development and application of nanowires for electrochemical sensors and biosensors are reviewed in this article. Next generation sensor platforms will require significant improvements in sensitivity, specificity and parallelism in order to meet the future needs in variety of fields. Sensors made of [...] Read more.

The development and application of nanowires for electrochemical sensors and biosensors are reviewed in this article. Next generation sensor platforms will require significant improvements in sensitivity, specificity and parallelism in order to meet the future needs in variety of fields. Sensors made of nanowires exploit some fundamental nanoscopic effect in order to meet these requirements. Nanowires are new materials, which have the characteristic of low weight with extraordinary mechanical, electrical, thermal and multifunctional properties. The advantages such as size scale, aspect ratio and other properties of nanowires are especially apparent in the use of electrical sensors such as electrochemical sensors and in the use of field-effect transistors. The preparation methods of nanowires and their properties are discussed along with their advantages towards electrochemical sensors and biosensors. Some key results from each article are summarized, relating the concept and mechanism behind each sensor, with experimental conditions as well as their behavior at different conditions. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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500 KiB

Open AccessReview

Electroanalysis of NADH Using Conducting and Redox Active Polymer/Carbon Nanotubes Modified Electrodes-A Review

by S. Ashok Kumar and Shen-Ming Chen

Sensors 2008, 8(2), 739-766; https://doi.org/10.3390/s8020739 - 6 Jan 2008

Cited by 134 | Viewed by 16897

Abstract

Past few decades, conducting and redox active polymers play a critical role in the development of transducers for biosensing. It has been evidenced by increasing numerous reports on conducting and redox active polymers incorporated electrodes for assay of biomolcules. This review highlights the [...] Read more.

Past few decades, conducting and redox active polymers play a critical role in the development of transducers for biosensing. It has been evidenced by increasing numerous reports on conducting and redox active polymers incorporated electrodes for assay of biomolcules. This review highlights the potential uses of electrogenerated polymer modified electrodes and polymer/carbon nanotubes composite modified electrodes for electroanalysis of reduced form of nicotinamide adenine dinuceltoide (NADH). In addition, carbon electrodes modified with organic and inorganic materials as modifier have been discussed in detail for the quantification of NADH based on mediator or mediator-less methods. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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666 KiB

Open AccessReview

An Overview of Label-free Electrochemical Protein Sensors

by Mun\'delanji Vestergaard, Kagan Kerman and Eiichi Tamiya

Sensors 2007, 7(12), 3442-3458; https://doi.org/10.3390/s7123442 - 20 Dec 2007

Cited by 160 | Viewed by 15149

Abstract

Electrochemical-based protein sensors offer sensitivity, selectivity and reliabilityat a low cost, making them very attractive tools for protein detection. Although the sensorsuse a broad range of different chemistries, they all depend on the solid electrode surface,interactions with the target protein and the molecular [...] Read more.

Electrochemical-based protein sensors offer sensitivity, selectivity and reliabilityat a low cost, making them very attractive tools for protein detection. Although the sensorsuse a broad range of different chemistries, they all depend on the solid electrode surface,interactions with the target protein and the molecular recognition layer. Traditionally, redoxenzymes have provided the molecular recognition elements from which target proteins haveinteracted with. This necessitates that the redox-active enzymes couple with electrodesurfaces and usually requires the participation of added diffusional components, or assemblyof the enzymes in functional chemical matrices. These complications, among many others,have seen a trend towards non-enzymatic-based electrochemical protein sensors. Severalelectrochemical detection approaches have been exploited. Basically, these have fallen intotwo categories: labeled and label-free detection systems. The former rely on a redox-activesignal from a reporter molecule or a label, which changes upon the interaction of the targetprotein. In this review, we discuss the label-free electrochemical detection of proteins,paying particular emphasis to those that exploit intrinsic redox-active amino acids. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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