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17 pages, 3890 KiB

Open AccessArticle

Electrochemical Biosensor for Nitrite Based on Polyacrylic-Graphene Composite Film with Covalently Immobilized Hemoglobin

by Raja Zaidatul Akhmar Raja Jamaluddin, Lee Yook Heng, Ling Ling Tan and Kwok Feng Chong

Sensors 2018, 18(5), 1343; https://doi.org/10.3390/s18051343 - 26 Apr 2018

Cited by 23 | Viewed by 4467

Abstract

A new biosensor for the analysis of nitrite in food was developed based on hemoglobin (Hb) covalently immobilized on the succinimide functionalized poly(n-butyl acrylate)-graphene [poly(nBA)-rGO] composite film deposited on a carbon-paste screen-printed electrode (SPE). The immobilized Hb on the poly(nBA)-rGO conducting matrix exhibited [...] Read more.

A new biosensor for the analysis of nitrite in food was developed based on hemoglobin (Hb) covalently immobilized on the succinimide functionalized poly(n-butyl acrylate)-graphene [poly(nBA)-rGO] composite film deposited on a carbon-paste screen-printed electrode (SPE). The immobilized Hb on the poly(nBA)-rGO conducting matrix exhibited electrocatalytic ability for the reduction of nitrite with significant enhancement in the reduction peak at −0.6 V versus Ag/AgCl reference electrode. Thus, direct determination of nitrite can be achieved by monitoring the cathodic peak current signal of the proposed polyacrylic-graphene hybrid film-based voltammetric nitrite biosensor. The nitrite biosensor exhibited a reproducible dynamic linear response range from 0.05–5 mg L⁻¹ nitrite and a detection limit of 0.03 mg L⁻¹. No significant interference was observed by potential interfering ions such as Ca²⁺, Na⁺, K⁺, NH₄⁺, Mg²⁺, and NO₃⁻ ions. Analysis of nitrite in both raw and processed edible bird’s nest (EBN) samples demonstrated recovery of close to 100%. The covalent immobilization of Hb on poly(nBA)-rGO composite film has improved the performance of the electrochemical nitrite biosensor in terms of broader detection range, lower detection limit, and prolonged biosensor stability. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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11 pages, 1182 KiB

Open AccessArticle

Rapid, High Affinity Binding by a Fluorescein Templated Copolymer Combining Covalent, Hydrophobic, and Acid–Base Noncovalent Crosslinks

by Casey J. Grenier, Anthony Timberman, Rongfang Yang, John Csoros, Alex Papantones, Leila F. Deravi and W. Rudolf Seitz

Sensors 2018, 18(5), 1330; https://doi.org/10.3390/s18051330 - 25 Apr 2018

Cited by 9 | Viewed by 3957

Abstract

A new type of biomimetic templated copolymer has been prepared by reverse addition fragmentation chain transfer polymerization (RAFT) in dioxane. The initial formulation includes the template fluorescein, N-isopropylacrylamide (NIPAM, 84 mol %), methacrylic acid (MAA, 5-mol %), 4-vinylpyridine (4-VP, 9 mmol %), [...] Read more.

A new type of biomimetic templated copolymer has been prepared by reverse addition fragmentation chain transfer polymerization (RAFT) in dioxane. The initial formulation includes the template fluorescein, N-isopropylacrylamide (NIPAM, 84 mol %), methacrylic acid (MAA, 5-mol %), 4-vinylpyridine (4-VP, 9 mmol %), and N,N′-methylenebis(acrylamide) (MBA, 2 mol %). PolyNIPAM is a thermosensitive polymer that comes out of aqueous solution above its lower critical solution temperature forming hydrophobic ‘crosslinks’. MAA and 4-VP interact in dioxane forming acid–base crosslinks. The excess 4-VP serves as a recognition monomer organizing around the template fluorescein to form a binding site that is held in place by the noncovalent and covalent crosslinks. The MBA is a covalent crosslinker. The RAFT agent in the resulting copolylmer was reduced to a thiol and attached to gold nanoparticles. The gold nanoparticle bound copolymer binds fluorescein completely in less than two seconds with an affinity constant greater than 10⁸ M⁻¹. A reference copolymer prepared with the same monomers by the same procedure binds fluorescein much more weakly. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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16 pages, 2413 KiB

Open AccessArticle

A Surface Plasmon Resonance-Based Optical Fiber Probe Fabricated with Electropolymerized Molecular Imprinting Film for Melamine Detection

by Wei Li, Yongping Zheng, Tingwei Zhang, Songjie Wu, Jue Zhang and Jing Fang

Sensors 2018, 18(3), 828; https://doi.org/10.3390/s18030828 - 9 Mar 2018

Cited by 17 | Viewed by 4909

Abstract

Molecularly imprinted polymer (MIP) films prepared by bulk polymerization suffer from numerous deficiencies, including poor mass transfer ability and difficulty in controlling reaction rate and film thickness, which usually result in poor repeatability. However, polymer film synthesized by electropolymerization methods benefit from high [...] Read more.

Molecularly imprinted polymer (MIP) films prepared by bulk polymerization suffer from numerous deficiencies, including poor mass transfer ability and difficulty in controlling reaction rate and film thickness, which usually result in poor repeatability. However, polymer film synthesized by electropolymerization methods benefit from high reproducibility, simplicity and rapidity of preparation. In the present study, an Au film served as the refractive index-sensitive metal film to couple with the light leaked out from optical fiber core and the electrode for electropolymerizing MIP film simultaneously. The manufactured probe exhibited satisfactory sensitivity and specificity. Furthermore, the surface morphology and functional groups of the synthesized MIP film were characterized by Atomic Force Microscopy (AFM) and Fourier transform infrared microspectroscopy (FTIR) for further insights into the adsorption and desorption processes. Given the low cost, label-free test, simple preparation process and fast response, this method has a potential application to monitor substances in complicated real samples for out-of-lab test in the future. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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9 pages, 1977 KiB

Open AccessArticle

Conductometric Sensor for PAH Detection with Molecularly Imprinted Polymer as Recognition Layer

by Usman Latif, Liu Ping and Franz L. Dickert

Sensors 2018, 18(3), 767; https://doi.org/10.3390/s18030767 - 3 Mar 2018

Cited by 28 | Viewed by 8242

Abstract

A conductometric sensor based on screen-printed interdigital gold electrodes on glass substrate coated with molecularly imprinted polyurethane layers was fabricated to detect polycyclic aromatic hydrocarbons (PAHs) in water. The results prove that screen-printed interdigital electrodes are very suitable transducers to fabricate low-cost sensor [...] Read more.

A conductometric sensor based on screen-printed interdigital gold electrodes on glass substrate coated with molecularly imprinted polyurethane layers was fabricated to detect polycyclic aromatic hydrocarbons (PAHs) in water. The results prove that screen-printed interdigital electrodes are very suitable transducers to fabricate low-cost sensor systems for measuring change in resistance of PAH-imprinted layers while exposing to different PAHs. The sensor showed good selectivity to its templated molecules and high sensitivity with a detection limit of 1.3 nmol/L e.g., for anthracene in water which is lower than WHO’s permissible limit. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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11 pages, 2507 KiB

Open AccessArticle

Towards Phosphate Detection in Hydroponics Using Molecularly Imprinted Polymer Sensors

by Christopher S. Storer, Zachary Coldrick, Daniel J. Tate, Jack Marsden Donoghue and Bruce Grieve

Sensors 2018, 18(2), 531; https://doi.org/10.3390/s18020531 - 10 Feb 2018

Cited by 23 | Viewed by 6001

Abstract

An interdigitated electrode sensor was designed and microfabricated for measuring the changes in the capacitance of three phosphate selective molecularly imprinted polymer (MIP) formulations, in order to provide hydroponics users with a portable nutrient sensing tool. The MIPs investigated were synthesised using different [...] Read more.

An interdigitated electrode sensor was designed and microfabricated for measuring the changes in the capacitance of three phosphate selective molecularly imprinted polymer (MIP) formulations, in order to provide hydroponics users with a portable nutrient sensing tool. The MIPs investigated were synthesised using different combinations of the functional monomers methacrylic acid (MAA) and N-allylthiourea, against the template molecules diphenyl phosphate, triethyl phosphate, and trimethyl phosphate. A cross-interference study between phosphate, nitrate, and sulfate was carried out for the MIP materials using an inductance, capacitance, and resistance (LCR) meter. Capacitance measurements were taken by applying an alternating current (AC) with a potential difference of 1 V root mean square (RMS) at a frequency of 1 kHz. The cross-interference study demonstrated a strong binding preference to phosphate over the other nutrient salts tested for each formulation. The size of template molecule and length of the functional monomer side groups also determined that a short chain functional monomer in combination with a template containing large R-groups produced the optimal binding site conditions when synthesising a phosphate selective MIP. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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10 pages, 3280 KiB

Open AccessArticle

Polymeric Flexible Immunosensor Based on Piezoresistive Micro-Cantilever with PEDOT/PSS Conductive Layer

by Rui Zhao and Ying Sun

Sensors 2018, 18(2), 451; https://doi.org/10.3390/s18020451 - 3 Feb 2018

Cited by 12 | Viewed by 6706

Abstract

In this paper, a fully polymeric micro-cantilever with the surface passivation layer of parylene-C and the strain resistor of poly(3,4-ethylenedioxythiophene)/poly (styrene sulfonate) (PEDOT/PSS) was proposed and demonstrated for immunoassays. By optimizing the design and fabrication of the polymeric micro-cantilever, a square resistance of [...] Read more.

In this paper, a fully polymeric micro-cantilever with the surface passivation layer of parylene-C and the strain resistor of poly(3,4-ethylenedioxythiophene)/poly (styrene sulfonate) (PEDOT/PSS) was proposed and demonstrated for immunoassays. By optimizing the design and fabrication of the polymeric micro-cantilever, a square resistance of 220 Ω/□ for PEDOT/PSS conductive layer have been obtained. The experimental spring constant and the deflection sensitivity were measured to be 0.017 N/m and 8.59 × 10⁻⁷ nm⁻¹, respectively. The biological sensing performances of polymeric micro-cantilever were investigated by the immunoassay for human immunoglobulin G (IgG). The immunosensor was experimentally demonstrated to have a linear behavior for the detection of IgG within the concentrations of 10~100 ng/mL with a limit of detection (LOD) of 10 ng/mL. The experimental results indicate that the proposed polymeric flexible conductive layer-based sensors are capable of detecting trace biological substances. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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11 pages, 2355 KiB

Open AccessArticle

Combined Layer/Particle Approaches in Surface Molecular Imprinting of Proteins: Signal Enhancement and Competition

by Nam Van Ho Phan, Hermann F. Sussitz, Eva Ladenhauf, Dietmar Pum and Peter A. Lieberzeit

Sensors 2018, 18(1), 180; https://doi.org/10.3390/s18010180 - 10 Jan 2018

Cited by 18 | Viewed by 6229

Abstract

Herein we report novel approaches to the molecular imprinting of proteins utilizing templates sizing around 10 nm and some 100 nm. The first step comprised synthesizing nanoparticles of molecularly imprinted polymers (MIP) towards bovine serum albumin (BSA) and characterizing them according to size [...] Read more.

Herein we report novel approaches to the molecular imprinting of proteins utilizing templates sizing around 10 nm and some 100 nm. The first step comprised synthesizing nanoparticles of molecularly imprinted polymers (MIP) towards bovine serum albumin (BSA) and characterizing them according to size and binding capacity. In a second step, they were utilized as templates. Quartz crystal microbalances (QCM) coated with MIP thin films based on BSA MIP nanoparticles lead to a two-fold increase in sensor responses, compared with the case of directly using the protein as the template. This also established that individual BSA molecules exhibit different “epitopes” for molecular imprinting on their outer surfaces. In light of this knowledge, a possible MIP-based biomimetic assay format was tested by exposing QCM coated with BSA MIP thin films to mixtures of BSA and imprinted and non-imprinted polymer (NIP) nanoparticles. At high protein concentrations (1000 ppm) measurements revealed aggregation behavior, i.e., BSA binding MIP NP onto the MIP surface. This increased sensor responses by more than 30% during proof of concept measurements. At lower a BSA concentration (500 ppm), thin films and particles revealed competitive behavior. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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4953 KiB

Open AccessArticle

Single-Shot Detection of Neurotransmitters in Whole-Blood Samples by Means of the Heat-Transfer Method in Combination with Synthetic Receptors

by Thijs Vandenryt, Bart Van Grinsven, Kasper Eersels, Peter Cornelis, Safira Kholwadia, Thomas J. Cleij, Ronald Thoelen, Ward De Ceuninck, Marloes Peeters and Patrick Wagner

Sensors 2017, 17(12), 2701; https://doi.org/10.3390/s17122701 - 23 Nov 2017

Cited by 18 | Viewed by 5518

Abstract

Serotonin is an important neurotransmitter that plays a major role in the pathogenesis of a variety of conditions, including psychiatric disorders. The detection of serotonin typically relies on high-performance liquid chromatography (HPLC), an expensive technique that requires sophisticated equipment and trained personnel, and [...] Read more.

Serotonin is an important neurotransmitter that plays a major role in the pathogenesis of a variety of conditions, including psychiatric disorders. The detection of serotonin typically relies on high-performance liquid chromatography (HPLC), an expensive technique that requires sophisticated equipment and trained personnel, and is not suitable for point-of-care applications. In this contribution, we introduce a novel sensor platform that can measure spiked neurotransmitter concentrations in whole blood samples in a fast and low-cost manner by combining synthetic receptors with a thermal readout technique—the heat-transfer method. In addition, the design of a miniaturized version of the sensing platform is presented that aims to bridge the gap between measurements in a laboratory setting and point-of-care measurements. This fully automated and integrated, user-friendly design features a capillary pumping unit that is compatible with point-of-care sampling techniques such as a blood lancet device (sample volume—between 50 µL and 300 µL). Sample pre-treatment is limited to the addition of an anti-coagulant. With this fully integrated setup, it is possible to successfully discriminate serotonin from a competitor neurotransmitter (histamine) in whole blood samples. This is the first demonstration of a point-of-care ready device based on synthetic receptors for the screening of neurotransmitters in complex matrices, illustrating the sensor’s potential application in clinical research and diagnosis of e.g., early stage depression. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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2460 KiB

Open AccessArticle

Polymethacrylate Coated Electrospun PHB Fibers as a Functionalized Platform for Bio-Diagnostics: Confirmation Analysis on the Presence of Immobilized IgG Antibodies against Dengue Virus

by Samira Hosseini, Pedram Azari, Martín F. Jiménez-Moreno, Aida Rodriguez-Garcia, Belinda Pingguan-Murphy, Marc J. Madou and Sergio O. Martínez-Chapa

Sensors 2017, 17(10), 2292; https://doi.org/10.3390/s17102292 - 9 Oct 2017

Cited by 12 | Viewed by 5294

Abstract

In this article, a combination of far field electrospinning (FFES) and free-radical polymerization has been used to create a unique platform for protein immobilization via the physical attachment of biomolecules to the surface of the fiber mats. The large specific surface area of [...] Read more.

In this article, a combination of far field electrospinning (FFES) and free-radical polymerization has been used to create a unique platform for protein immobilization via the physical attachment of biomolecules to the surface of the fiber mats. The large specific surface area of the fibers with its tailored chemistry provides a desirable platform for effective analyte-surface interaction. The detailed analysis of protein immobilization on a newly developed bio-receptive surface plays a vital role to gauge its advantages in bio-diagnostic applications. We relied on scanning electron microscopy (SEM), diameter range analysis, and X-ray photoelectron spectroscopy (XPS), along with thermal gravimetric analysis (TGA), water-in-air contact angle analysis (WCA), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) to study our developed platforms and to provide valuable information regarding the presence of biomolecular entities on the surface. Detailed analyses of the fiber mats before and after antibody immobilization have shown obvious changes on the surface of the bioreceptive surface including: (i) an additional peak corresponding to the presence of an antibody in TGA analysis; (ii) extra FTIR peaks corresponding to the presence of antibodies on the coated fiber platforms; and (iii) a clear alteration in surface roughness recorded by AFM analysis. Confirmation analyses on protein immobilization are of great importance as they underlay substantial grounds for various biosensing applications. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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2607 KiB

Open AccessArticle

A Microneedle Functionalized with Polyethyleneimine and Nanotubes for Highly Sensitive, Label-Free Quantification of DNA

by Darius Saadat-Moghaddam and Jong-Hoon Kim

Sensors 2017, 17(8), 1883; https://doi.org/10.3390/s17081883 - 16 Aug 2017

Cited by 8 | Viewed by 4852

Abstract

The accurate measure of DNA concentration is necessary for many DNA-based biological applications. However, the current methods are limited in terms of sensitivity, reproducibility, human error, and contamination. Here, we present a microneedle functionalized with polyethyleneimine (PEI) and single-walled carbon nanotubes (SWCNTs) for [...] Read more.

The accurate measure of DNA concentration is necessary for many DNA-based biological applications. However, the current methods are limited in terms of sensitivity, reproducibility, human error, and contamination. Here, we present a microneedle functionalized with polyethyleneimine (PEI) and single-walled carbon nanotubes (SWCNTs) for the highly sensitive quantification of DNA. The microneedle was fabricated using ultraviolet (UV) lithography and anisotropic etching, and then functionalized with PEI and SWCNTs through a dip coating process. The electrical characteristics of the microneedle change with the accumulation of DNA on the surface. Current-voltage measurements in deionized water were conducted to study these changes in the electrical properties of the sensor. The sensitivity test found the signal to be discernable from the noise level down to 100 attomolar (aM), demonstrating higher sensitivity than currently available UV fluorescence and UV absorbance based methods. A microneedle without any surface modification only had a 100 femtomolar (fM) sensitivity. All measurement results were consistent with fluorescence microscopy. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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Review

Jump to: Research

16 pages, 3242 KiB

Open AccessReview

Responsive Polydiacetylene Vesicles for Biosensing Microorganisms

by Estelle Lebègue, Carole Farre, Catherine Jose, Joelle Saulnier, Florence Lagarde, Yves Chevalier, Carole Chaix and Nicole Jaffrezic-Renault

Sensors 2018, 18(2), 599; https://doi.org/10.3390/s18020599 - 15 Feb 2018

Cited by 42 | Viewed by 7353

Abstract

Polydiacetylene (PDA) inserted in films or in vesicles has received increasing attention due to its property to undergo a blue-to-red colorimetric transition along with a change from non-fluorescent to fluorescent upon application of various stimuli. In this review paper, the principle for the [...] Read more.

Polydiacetylene (PDA) inserted in films or in vesicles has received increasing attention due to its property to undergo a blue-to-red colorimetric transition along with a change from non-fluorescent to fluorescent upon application of various stimuli. In this review paper, the principle for the detection of various microorganisms (bacteria, directly detected or detected through the emitted toxins or through their DNA, and viruses) and of antibacterial and antiviral peptides based on these responsive PDA vesicles are detailed. The analytical performances obtained, when vesicles are in suspension or immobilized, are given and compared to those of the responsive vesicles mainly based on the vesicle encapsulation method. Many future challenges are then discussed. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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3858 KiB

Open AccessReview

Real Time Analysis of Bioanalytes in Healthcare, Food, Zoology and Botany

by Tianqi Wang, Ashwin Ramnarayanan and Huanyu Cheng

Sensors 2018, 18(1), 5; https://doi.org/10.3390/s18010005 - 21 Dec 2017

Cited by 22 | Viewed by 7661

Abstract

The growing demand for real time analysis of bioanalytes has spurred development in the field of wearable technology to offer non-invasive data collection at a low cost. The manufacturing processes for creating these sensing systems vary significantly by the material used, the type [...] Read more.

The growing demand for real time analysis of bioanalytes has spurred development in the field of wearable technology to offer non-invasive data collection at a low cost. The manufacturing processes for creating these sensing systems vary significantly by the material used, the type of sensors needed and the subject of study as well. The methods predominantly involve stretchable electronic sensors to monitor targets and transmit data mainly through flexible wires or short-range wireless communication devices. Capable of conformal contact, the application of wearable technology goes beyond the healthcare to fields of food, zoology and botany. With a brief review of wearable technology and its applications to various fields, we believe this mini review would be of interest to the reader in broad fields of materials, sensor development and areas where wearable sensors can provide data that are not available elsewhere. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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