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18 pages, 3266 KiB

Open AccessArticle

Nanostructured P3HT as a Promising Sensing Element for Real-Time, Dynamic Detection of Gaseous Acetone

by Cristina Bertoni, Pasquale Naclerio, Emanuele Viviani, Simone Dal Zilio, Sergio Carrato and Alessandro Fraleoni-Morgera

Sensors 2019, 19(6), 1296; https://doi.org/10.3390/s19061296 - 14 Mar 2019

Cited by 13 | Viewed by 3614

Abstract

The dynamic response of gas sensors based on poly(3-hexylthiophene) (P3HT) nanofibers (NFs) to gaseous acetone was assessed using a setup based on flow-injection analysis, aimed at emulating actual breath exhalation. The setup was validated by using a commercially available sensor. The P3HT NFs [...] Read more.

The dynamic response of gas sensors based on poly(3-hexylthiophene) (P3HT) nanofibers (NFs) to gaseous acetone was assessed using a setup based on flow-injection analysis, aimed at emulating actual breath exhalation. The setup was validated by using a commercially available sensor. The P3HT NFs sensors tested in dynamic flow conditions showed satisfactory reproducibility down to about 3.5 ppm acetone concentration, a linear response over a clinically relevant concentration range (3.5-35 ppm), excellent baseline recovery and reversibility upon repeated exposures to the analyte, short pulse rise and fall times (less than 1 s and about 2 s, respectively) and low power consumption (few nW), with no relevant response to water. Comparable responses’ decay times under either nitrogen or dry air suggest that the mechanisms at work is mainly attributable to specific analyte-semiconducting polymer interactions. These results open the way to the use of P3HT NFs-based sensing elements for the realization of portable, real-time electronic noses for on-the-fly exhaled breath analysis. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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16 pages, 3131 KiB

Open AccessArticle

Electrochemical Immunosensor Based on Nanoelectrode Ensembles for the Serological Analysis of IgG-type Tissue Transglutaminase

by Henok B. Habtamu, Tarcisio Not, Luigina De Leo, Sara Longo, Ligia M. Moretto and Paolo Ugo

Sensors 2019, 19(5), 1233; https://doi.org/10.3390/s19051233 - 11 Mar 2019

Cited by 18 | Viewed by 4709

Abstract

Celiac disease (CD) is a gluten-dependent autoimmune disorder affecting a significant percentage of the general population, with increasing incidence particularly for children. Reliable analytical methods suitable for the serological diagnosis of the disorder are urgently required for performing both the early diagnosis and [...] Read more.

Celiac disease (CD) is a gluten-dependent autoimmune disorder affecting a significant percentage of the general population, with increasing incidence particularly for children. Reliable analytical methods suitable for the serological diagnosis of the disorder are urgently required for performing both the early diagnosis and the follow-up of a patient adhering to a gluten-free diet. Herein we report on the preparation and application of a novel electrochemical immunosensor based on the use of ensembles of gold nanoelectrodes (NEEs) for the detection of anti-tissue transglutaminase (anti-tTG), which is considered one reliable serological marker for CD. To this end, we take advantage of the composite nature of the nanostructured surface of membrane-templated NEEs by functionalizing the polycarbonate surface of the track-etched membrane with tissue transglutaminase. Incubation of the functionalized NEE in anti-tTG samples results in the capture of the anti-tTG antibody. Confirmation of the recognition event is achieved by incubating the NEE with a secondary antibody labelled with horseradish peroxidase (HRP): in the presence of H₂O₂ as substrate and hydroquinone as redox mediator, an electrocatalytic current is indeed generated whose increment is proportional to the amount of anti-tTG captured from the sample. The optimized sensor allows a detection limit of 1.8 ng mL⁻¹, with satisfactory selectivity and reproducibility. Analysis of serum samples from 28 individuals, some healthy and some affected by CD, furnished analytical results comparable with those achieved by classical fluoroenzyme immunoassay (FEIA). We note that the NEE-based immunosensor developed here detects the IgG isotype of anti-tTG, while FEIA detects the IgA isotype, which is not a suitable diagnostic marker for IgA-deficient patients. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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9 pages, 1706 KiB

Open AccessArticle

Single-Walled Carbon Nanotubes as Enhancing Substrates for PNA-Based Amperometric Genosensors

by Simone Fortunati, Andrea Rozzi, Federica Curti, Marco Giannetto, Roberto Corradini and Maria Careri

Sensors 2019, 19(3), 588; https://doi.org/10.3390/s19030588 - 30 Jan 2019

Cited by 13 | Viewed by 4187

Abstract

A new amperometric sandwich-format genosensor has been implemented on single-walled carbon nanotubes screen printed electrodes (SWCNT-SPEs) and compared in terms of performance with analogous genoassays developed using the same methodology on non-nanostructured glassy carbon platforms (GC-SPE). The working principle of the genosensors is [...] Read more.

A new amperometric sandwich-format genosensor has been implemented on single-walled carbon nanotubes screen printed electrodes (SWCNT-SPEs) and compared in terms of performance with analogous genoassays developed using the same methodology on non-nanostructured glassy carbon platforms (GC-SPE). The working principle of the genosensors is based on the covalent immobilization of Peptide Nucleic Acid (PNA) capture probes (CP) on the electrode surface, carried out through the carboxylic functions present on SWCNT-SPEs (carboxylated SWCNT) or electrochemically induced on GC-SPEs. The sequence of the CP was complementary to a 20-mer portion of the target DNA; a second biotin-tagged PNA signalling probe (SP), with sequence complementary to a different contiguous portion of the target DNA, was used to obtain a sandwich hybrid with an Alkaline Phosphatase-streptavidin conjugate (ALP-Strp). Comparison of the responses obtained from the SWCNT-SPEs with those produced from the non-nanostructured substrates evidenced the remarkable enhancement effect given by the nanostructured electrode platforms, achieved both in terms of loading capability of PNA probes and amplification of the electron transfer phenomena exploited for the signal transduction, giving rise to more than four-fold higher sensitivity when using SWCNT-SPEs. The nanostructured substrate allowed to reach limit of detection (LOD) of 71 pM and limit of quantitation (LOQ) of 256 pM, while the corresponding values obtained with GC-SPEs were 430 pM and 1.43 nM, respectively. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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12 pages, 3591 KiB

Open AccessArticle

A Flexible Platform of Electrochemically Functionalized Carbon Nanotubes for NADH Sensors

by Aranzazu Heras, Fabio Vulcano, Jesus Garoz-Ruiz, Nicola Porcelli, Fabio Terzi, Alvaro Colina, Renato Seeber and Chiara Zanardi

Sensors 2019, 19(3), 518; https://doi.org/10.3390/s19030518 - 26 Jan 2019

Cited by 6 | Viewed by 3850

Abstract

A flexible electrode system entirely constituted by single-walled carbon nanotubes (SWCNTs) has been proposed as the sensor platform for β-nicotinamide adenine dinucleotide (NADH) detection. The performance of the device, in terms of potential at which the electrochemical process takes place, significantly improves by [...] Read more.

A flexible electrode system entirely constituted by single-walled carbon nanotubes (SWCNTs) has been proposed as the sensor platform for β-nicotinamide adenine dinucleotide (NADH) detection. The performance of the device, in terms of potential at which the electrochemical process takes place, significantly improves by electrochemical functionalization of the carbon-based material with a molecule possessing an o-hydroquinone residue, namely caffeic acid. Both the processes of SWCNT functionalization and NADH detection have been studied by combining electrochemical and spectroelectrochemical experiments, in order to achieve direct evidence of the electrode modification by the organic residues and to study the electrocatalytic activity of the resulting material in respect to functional groups present at the electrode/solution interface. Electrochemical measurements performed at the fixed potential of +0.30 V let us envision the possible use of the device as an amperometric sensor for NADH detection. Spectroelectrochemistry also demonstrates the effectiveness of the device in acting as a voltabsorptometric sensor for the detection of this same analyte by exploiting this different transduction mechanism, potentially less prone to the possible presence of interfering species. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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13 pages, 5005 KiB

Open AccessArticle

Sensing Properties of Oxidized Nanostructured Silicon Surface on Vaporized Molecules

by Nikola Baran, Hrvoje Gebavi, Lara Mikac, Davor Ristić, Marijan Gotić, Kamran Ali Syed and Mile Ivanda

Sensors 2019, 19(1), 119; https://doi.org/10.3390/s19010119 - 1 Jan 2019

Cited by 13 | Viewed by 3976

Abstract

Porous silicon has been intensely studied for the past several decades and its applications were found in photovoltaics, biomedicine, and sensors. An important aspect for sensing devices is their long–term stability. One of the more prominent changes that occur with porous silicon as [...] Read more.

Porous silicon has been intensely studied for the past several decades and its applications were found in photovoltaics, biomedicine, and sensors. An important aspect for sensing devices is their long–term stability. One of the more prominent changes that occur with porous silicon as it is exposed to atmosphere is oxidation. In this work we study the influence of oxidation on the sensing properties of porous silicon. Porous silicon layers were prepared by electrochemical etching and oxidized in a tube furnace. We observed that electrical resistance of oxidized samples rises in response to the increasing ambient concentration of organic vapours and ammonia gas. Furthermore, we note the sensitivity is dependent on the oxygen treatment of the porous layer. This indicates that porous silicon has a potential use in sensing of organic vapours and ammonia gas when covered with an oxide layer. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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22 pages, 14228 KiB

Open AccessArticle

Fast Hydrogenation and Dehydrogenation of Pt/Pd Bimetal Decorated over Nano-Structured Ag Islands Grown on Alumina Substrates

by Md Habibur Rahaman, Usman Yaqoob and Hyeon Cheol Kim

Sensors 2019, 19(1), 86; https://doi.org/10.3390/s19010086 - 27 Dec 2018

Cited by 8 | Viewed by 4168

Abstract

This study reports the fast hydrogenation and dehydrogenation of ultra-thin discrete platinum/palladium (Pt/Pd) bimetal over nano-structured Ag islands grown on rough alumina substrate by a RF magnetron sputtering technique. The morphology of Ag nanoislands was optimized by RF magnetron sputtering and rapid thermal [...] Read more.

This study reports the fast hydrogenation and dehydrogenation of ultra-thin discrete platinum/palladium (Pt/Pd) bimetal over nano-structured Ag islands grown on rough alumina substrate by a RF magnetron sputtering technique. The morphology of Ag nanoislands was optimized by RF magnetron sputtering and rapid thermal annealing process. Later, Pt/Pd bimetal (10/10) nm were deposited by RF magnetron sputtering on the nanostructured Ag islands. After the surface morphological optimization of Ag nanoislands, the resultant structure Pt/Pd@Ag nanoislands at alumina substrate showed a fast and enhanced hydrogenation and dehydrogenation (20/25 s), response magnitude of 2.3% (10,000 ppm), and a broad detection range of 500 to 40,000 ppm at the operating temperature of 120 °C. The superior hydrogenation and dehydrogenation features can be attributed to the hydrogen induced changes in the work function of Pt/Pd bimetal which enhances the coulomb scattering of percolated Pt/Pd@Ag nanoislands. More importantly, the atomic arrangements and synergetic effects of complex metal alloy interfacial structure on Ag nanoislands, supported by rough alumina substrate incorporate the vital role in accelerating the H₂ absorption and desorption properties. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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14 pages, 2448 KiB

Open AccessArticle

Assessment of the Polyphenol Indices and Antioxidant Capacity for Beers and Wines Using a Tyrosinase-Based Biosensor Prepared by Sinusoidal Current Method

by Juan José García-Guzmán, David López-Iglesias, Laura Cubillana-Aguilera, Cecilia Lete, Stelian Lupu, José María Palacios-Santander and Dolores Bellido-Milla

Sensors 2019, 19(1), 66; https://doi.org/10.3390/s19010066 - 25 Dec 2018

Cited by 33 | Viewed by 4290

Abstract

The application of a novel Poly(3,4-ethylenedioxythiophene)-Tyrosinase/Sonogel-Carbon electrode (PEDOT-Tyr/SNGC) biosensor to beers and wines analysis is proposed. This biosensor implies a new Sinusoidal Current (SC) electrodeposition method to immobilize the enzyme generating a nanostructure surface. The biosensors were characterized electrochemically, employing cyclic voltammetry and [...] Read more.

The application of a novel Poly(3,4-ethylenedioxythiophene)-Tyrosinase/Sonogel-Carbon electrode (PEDOT-Tyr/SNGC) biosensor to beers and wines analysis is proposed. This biosensor implies a new Sinusoidal Current (SC) electrodeposition method to immobilize the enzyme generating a nanostructure surface. The biosensors were characterized electrochemically, employing cyclic voltammetry and electrochemical impedance spectroscopy. Sensitivity, limit of detection, and correlation coefficients of the linear fitting were 2.40 × 10⁻⁴ µA·µM⁻¹, 4.33 µM, and R² = 0.9987, respectively. Caffeic acid is used as the reference polyphenol. A sampling of nine beers (four lager, three stout, and two non-alcoholic beers), and four wines (three red and one white wine) purchased in a local store was performed. The Polyphenol indeces for beers and wines have been assessed using the proposed biosensor, and the obtained values are in agreement with the literature data. Antioxidant properties of the samples using the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical spectrophotometric method were also evaluated. The correlation between the polyphenol index and the antioxidant capacity was obtained for beers and wines. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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16 pages, 1077 KiB

Open AccessArticle

Optimization of Gas Sensors Based on Advanced Nanomaterials through Split-Plot Designs and GLMMs

by Rossella Berni and Francesco Bertocci

Sensors 2018, 18(11), 3858; https://doi.org/10.3390/s18113858 - 9 Nov 2018

Cited by 2 | Viewed by 3488

Abstract

This paper deals with the planning and modeling of a split-plot experiment to improve novel gas sensing materials based on Perovskite, a nano-structured, semi-conductor material that is sensitive to changes in the concentration of hazardous gas in the ambient air. The study addresses [...] Read more.

This paper deals with the planning and modeling of a split-plot experiment to improve novel gas sensing materials based on Perovskite, a nano-structured, semi-conductor material that is sensitive to changes in the concentration of hazardous gas in the ambient air. The study addresses both applied and theoretical issues. More precisely, it focuses on (i) the detection of harmful gases, e.g., NO

_{2}

and CO, which have a great impact on industrial applications as well as a significantly harmful impact on human health; (ii) the planning and modeling of a split-plot design for the two target gases by applying a dual-response modeling approach in which two models, e.g., location and dispersion models, are estimated; and (iii) a robust process optimization conducted in the final modeling step for each target gas and for each gas sensing material, conditioned to the minimization of the working temperature. The dual-response modeling allows us to achieve satisfactory estimates for the process variables and, at the same time, good diagnostic valuations. Optimal solutions are obtained for each gas sensing material while also improving the results achieved from previous studies. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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8 pages, 2399 KiB

Open AccessArticle

Measurement of Core Body Temperature Using Graphene-Inked Infrared Thermopile Sensor

by Jorge S. Chaglla E., Numan Celik and Wamadeva Balachandran

Sensors 2018, 18(10), 3315; https://doi.org/10.3390/s18103315 - 3 Oct 2018

Cited by 37 | Viewed by 7233

Abstract

Continuous and reliable measurements of core body temperature (CBT) are vital for studies on human thermoregulation. Because tympanic membrane directly reflects the temperature of the carotid artery, it is an accurate and non-invasive method to record CBT. However, commercial tympanic thermometers lack portability [...] Read more.

Continuous and reliable measurements of core body temperature (CBT) are vital for studies on human thermoregulation. Because tympanic membrane directly reflects the temperature of the carotid artery, it is an accurate and non-invasive method to record CBT. However, commercial tympanic thermometers lack portability and continuous measurements. In this study, graphene inks were utilized to increase the accuracy of the temperature measurements from the ear by coating graphene platelets on the lens of an infrared thermopile sensor. The proposed ear-based device was designed by investigating ear canal geometry and developed with 3D printing technology using the Computer-Aided Design (CAD) Software, SolidWorks 2016. It employs an Arduino Pro Mini and a Bluetooth module. The proposed system runs with a 3.7 V, 850 mAh rechargeable lithium-polymer battery that allows long-term, continuous monitoring. Raw data are continuously and wirelessly plotted on a mobile phone app. The test was performed on 10 subjects under resting and exercising in a total period of 25 min. Achieved results were compared with the commercially available Braun Thermoscan, Original Thermopile, and Cosinuss One ear thermometers. It is also comprehended that such system will be useful in personalized medicine as wearable in-ear device with wireless connectivity. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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11 pages, 1578 KiB

Open AccessArticle

A Novel Type Room Temperature Surface Photovoltage Gas Sensor Device

by Monika Kwoka, Michal A. Borysiewicz, Pawel Tomkiewicz, Anna Piotrowska and Jacek Szuber

Sensors 2018, 18(9), 2919; https://doi.org/10.3390/s18092919 - 3 Sep 2018

Cited by 5 | Viewed by 3338

Abstract

In this paper a novel type of a highly sensitive gas sensor device based on the surface photovoltage effect is described. It is based on the Kelvin probe approach. Porous ZnO nanostructured thin films deposited by the direct current (DC) reactive magnetron sputtering [...] Read more.

In this paper a novel type of a highly sensitive gas sensor device based on the surface photovoltage effect is described. It is based on the Kelvin probe approach. Porous ZnO nanostructured thin films deposited by the direct current (DC) reactive magnetron sputtering method are used as the active gas sensing electrode material. Crucially, the obtained gas sensing material exhibited a nanocoral surface morphology and surface Zn to O non-stoichiometry with respect to its bulk mass. Among other responses, the demonstrated SPV gas sensor device exhibits a high response to an NO₂ concentration as low as 1 ppm, with a signal to noise ratio of about 50 and a fast response time of several seconds under room temperature conditions. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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17 pages, 3284 KiB

Open AccessArticle

Effectiveness of Sensors Contact Metallization (Ti, Au, and Ru) and Biofunctionalization for Escherichia coli Detection

by Sabina Górska, Artur Rydosz, Ewa Brzozowska, Marek Drab, Krzysztof Wincza, Andrzej Gamian and Sławomir Gruszczyński

Sensors 2018, 18(9), 2912; https://doi.org/10.3390/s18092912 - 2 Sep 2018

Cited by 9 | Viewed by 4398

Abstract

In designing a bacteria biosensor, various issues must be addressed: the specificity of bacteria recognition, the immobilization of biomolecules that act as the bacteria receptor, and the selectivity of sensor surface. The aim of this paper was to examine how the biofunctionalized surface [...] Read more.

In designing a bacteria biosensor, various issues must be addressed: the specificity of bacteria recognition, the immobilization of biomolecules that act as the bacteria receptor, and the selectivity of sensor surface. The aim of this paper was to examine how the biofunctionalized surface of Ti, Au, and Ru metals reacts in contact with strains of Escherichia coli (E. coli). The focus on metal surfaces results from their future use as electrodes in high frequency biosensors, e.g., resonant circuits or transmission-line sections. First, the surfaces of different metals were chemically functionalized with 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde or with 3-glycidylooxypropyltrimethoxysilane (GPTMS) followed by N-(5-amino-1-carboxypentyl) iminodiacetic acid (AB-NTA) and NiCl₂. Secondly, the lipopolysaccharide binding protein (LBP), polyclonal anti-Escherichia coli antibody and bacteriophage protein gp37 were tested as bacteria receptors. The selectivity and specificity have been confirmed by the Enzyme-Linked Immunosorbent Assay (ELISA) and visualized by scanning electron microscopy at low landing energies. We noticed that LBP, polyclonal antibody, and gp37 were successfully immobilized on all studied metals and recognized the E. coli bacteria selectively. However, for the antibody, the highest reactivity was observed when Ti surface was modified, whereas the bacteria binding was comparable between LBP and gp37 on the functionalized Ru surfaces, independent from modification. Thus, all surfaces were biocompatible within the scope of biosensor functionality, with titanium functionalization showing the best performance. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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Review

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28 pages, 6510 KiB

Open AccessEditor’s ChoiceReview

Electrochemical Deposition of Nanomaterials for Electrochemical Sensing

by Domenica Tonelli, Erika Scavetta and Isacco Gualandi

Sensors 2019, 19(5), 1186; https://doi.org/10.3390/s19051186 - 8 Mar 2019

Cited by 148 | Viewed by 13269

Abstract

The most commonly used methods to electrodeposit nanomaterials on conductive supports or to obtain electrosynthesis nanomaterials are described. Au, layered double hydroxides (LDHs), metal oxides, and polymers are the classes of compounds taken into account. The electrochemical approach for the synthesis allows one [...] Read more.

The most commonly used methods to electrodeposit nanomaterials on conductive supports or to obtain electrosynthesis nanomaterials are described. Au, layered double hydroxides (LDHs), metal oxides, and polymers are the classes of compounds taken into account. The electrochemical approach for the synthesis allows one to obtain nanostructures with well-defined morphologies, even without the use of a template, and of variable sizes simply by controlling the experimental synthesis conditions. In fact, parameters such as current density, applied potential (constant, pulsed or ramp) and duration of the synthesis play a key role in determining the shape and size of the resulting nanostructures. This review aims to describe the most recent applications in the field of electrochemical sensors of the considered nanomaterials and special attention is devoted to the analytical figures of merit of the devices. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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35 pages, 10607 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Layer-by-Layer Nano-assembly: A Powerful Tool for Optical Fiber Sensing Applications

by Pedro J. Rivero, Javier Goicoechea and Francisco J. Arregui

Sensors 2019, 19(3), 683; https://doi.org/10.3390/s19030683 - 7 Feb 2019

Cited by 54 | Viewed by 7511

Abstract

The ability to tune the composition of nanostructured thin films is a hot topic for the design of functional coatings with advanced properties for sensing applications. The control of the structure at the nanoscale level enables an improvement of intrinsic properties (optical, chemical [...] Read more.

The ability to tune the composition of nanostructured thin films is a hot topic for the design of functional coatings with advanced properties for sensing applications. The control of the structure at the nanoscale level enables an improvement of intrinsic properties (optical, chemical or physical) in comparison with the traditional bulk materials. In this sense, among all the known nanofabrication techniques, the layer-by-layer (LbL) nano-assembly method is a flexible, easily-scalable and versatile approach which makes possible precise control of the coating thickness, composition and structure. The development of sensitive nanocoatings has shown an exceptional growth in optical fiber sensing applications due to their self-assembling ability with oppositely charged components in order to obtain a multilayer structure. This nanoassembly technique is a powerful tool for the incorporation of a wide variety of species (polyelectrolytes, metal/metal oxide nanoparticles, hybrid particles, luminescent materials, dyes or biomolecules) in the resultant multilayer structure for the design of high-performance optical fiber sensors. In this work we present a review of applications related to optical fiber sensors based on advanced LbL coatings in two related research areas of great interest for the scientific community, namely chemical sensing (pH, gases and volatile organic compounds detection) as well as biological/biochemical sensing (proteins, immunoglobulins, antibodies or DNA detection). Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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17 pages, 4690 KiB

Open AccessEditor’s ChoiceReview

Nanostructured Chemiresistive Gas Sensors for Medical Applications

by Noushin Nasiri and Christian Clarke

Sensors 2019, 19(3), 462; https://doi.org/10.3390/s19030462 - 23 Jan 2019

Cited by 85 | Viewed by 8894

Abstract

Treating diseases at their earliest stages significantly increases the chance of survival while decreasing the cost of treatment. Therefore, compared to traditional blood testing methods it is the goal of medical diagnostics to deliver a technique that can rapidly predict and if required [...] Read more.

Treating diseases at their earliest stages significantly increases the chance of survival while decreasing the cost of treatment. Therefore, compared to traditional blood testing methods it is the goal of medical diagnostics to deliver a technique that can rapidly predict and if required non-invasively monitor illnesses such as lung cancer, diabetes, melanoma and breast cancer at their very earliest stages, when the chance of recovery is significantly higher. To date human breath analysis is a promising candidate for fulfilling this need. Here, we highlight the latest key achievements on nanostructured chemiresistive sensors for disease diagnosis by human breath with focus on the multi-scale engineering of both composition and nano-micro scale morphology. We critically assess and compare state-of-the-art devices with the intention to provide direction for the next generation of chemiresistive nanostructured sensors. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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29 pages, 17176 KiB

Open AccessEditor’s ChoiceReview

Non-Covalent Functionalization of Carbon Nanotubes for Electrochemical Biosensor Development

by Yan Zhou, Yi Fang and Ramaraja P. Ramasamy

Sensors 2019, 19(2), 392; https://doi.org/10.3390/s19020392 - 18 Jan 2019

Cited by 250 | Viewed by 19291

Abstract

Carbon nanotubes (CNTs) have been widely studied and used for the construction of electrochemical biosensors owing to their small size, cylindrical shape, large surface-to-volume ratio, high conductivity and good biocompatibility. In electrochemical biosensors, CNTs serve a dual purpose: they act as immobilization support [...] Read more.

Carbon nanotubes (CNTs) have been widely studied and used for the construction of electrochemical biosensors owing to their small size, cylindrical shape, large surface-to-volume ratio, high conductivity and good biocompatibility. In electrochemical biosensors, CNTs serve a dual purpose: they act as immobilization support for biomolecules as well as provide the necessary electrical conductivity for electrochemical transduction. The ability of a recognition molecule to detect the analyte is highly dependent on the type of immobilization used for the attachment of the biomolecule to the CNT surface, a process also known as biofunctionalization. A variety of biofunctionalization methods have been studied and reported including physical adsorption, covalent cross-linking, polymer encapsulation etc. Each method carries its own advantages and limitations. In this review we provide a comprehensive review of non-covalent functionalization of carbon nanotubes with a variety of biomolecules for the development of electrochemical biosensors. This method of immobilization is increasingly being used in bioelectrode development using enzymes for biosensor and biofuel cell applications. Full article

(This article belongs to the Special Issue Nanostructured Surfaces in Sensing Systems)

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