Indium-tin-oxide Bioelectrode Research Articles

Enhanced Electrochemical Biosensing of the Sp17 Cancer Biomarker in Serum Samples via Engineered Two-Dimensional MoS2 Nanosheets on the Reduced Graphene Oxide Interface.

In the present investigation, we reported a label-free and highly effective immunosensor for the first time employing a nanostructured molybdenum disulfide nanosheets@reduced graphene oxide (nMoS2 NS@rGO) nanohybrid interface for the determination of sperm protein 17 (Sp17), an emerging cancer biomarker. We synthesized the nMoS2 NS@rGO nanohybrid using a one-step hydrothermal technique and then functionalized it with 3-aminopropyltriethoxysilane (APTES). Furthermore, the anti-Sp17 monoclonal antibodies were covalently attached to the APTES/nMoS2 NS@rGO/indium tin oxide (ITO) electrode utilizing 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide-N-hydroxy succinimide (EDC-NHS) coupling chemistry. Bovine serum albumin (BSA) was then used to block nonspecific binding regions on the anti-Sp17/APTES/nMoS2 NS@rGO/ITO bioelectrode. The morphological and structural features of the synthesized nanohybrid and the modified electrodes were studied using transmission electron microscopy, scanning electron microscopy with energy dispersive X-ray (EDX) composition studies, atomic force microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The immunoreaction between the Sp17 antigen and anti-Sp17 antibodies on the surface of the BSA/anti-Sp17/APTES/nMoS2 NS@rGO/ITO sensing bioelectrode was applied as the basis for the detection technique, which measured the electrocatalytic current and impedimetric response change. The designed BSA/anti-Sp17/APTES/nMoS2 NS@rGO/ITO bioelectrode showed improved amperometric and impedimetric biosensing performance in the response studies, including remarkable sensitivity (23.2 μA ng-1mL cm-2 and 0.48 kΩ mL ng-1 cm-2), wider linearity (0.05-8 and 1-8 ng mL-1), an excellent lower detection limit (0.13 and 0.23 ng mL-1), and a rapid response time of 20 min. The biosensor exhibited impressive storage durability lasting 7 weeks and showed remarkable precision in identifying Sp17 in serum samples from cancer patients, as confirmed using the enzyme-linked immunosorbent assay method.

Study of ITO Glass Electrode Modified with Iron Oxide Nanoparticles and Nafion for Glucose Biosensor Application

In this study, we report the fabrication of the indium tin oxide (ITO) glass electrode modified with iron oxide nanoparticles (IONPs) and nafion for glucose biosensor applications. The IONPs was synthesized using the precipitation method and functionalized with citric acid (CA) to provide hydrophilic surface and functional group for glucose oxidase (GOx) enzyme immobilization. The structural and morphological studies of CA-IONPs were characterized using X-ray diffractometer (XRD) and transmission electron microscope (TEM). The size of the IONPs measured from TEM image was ∼17nm. The bioelectrode designated as Nafion/GOx/CA-IONPs/ITO was developed by drop casting of the CA-IONPs, GOx and nafion on the ITO glass. The Nafion/GOx/CA-IONPs/ITO bioelectrode showed good electrochemical performance for glucose detection. The functionalized CA-IONPs acted as the catalyst and help to improve the electron transfer rate between GOx and ITO electrode. In addition, thin nafion film was coated on the electrode to prevent interference and improve chemical stability. The Nafion/GOx/CA-IONPs/ITO bioelectrode showed high sensitivity of 70.1μAmM-1cm-2 for the linear range of 1.0-8.0mM glucose concentrations.

Core–shell structured Ag@C for direct electrochemistry and hydrogen peroxide biosensor applications

Ag@C core–shell nano-composites have been prepared by a simple one-step hydrothermal method and are further explored for protein immobilization and bio-sensing. The electrochemical behavior of immobilized horseradish peroxidase (HRP) on Ag@C modified indium–tin–oxide (ITO) electrode and its application as H2O2 sensor are investigated. Electrochemical and UV–vis spectroscopic measurements demonstrated that Ag@C nano-composites provide excellent matrixes for the adsorption of HRP and the entrapped HRP retains its bioactivities. It is found that on the HRP–Ag@C/ITO electrode, HRP exhibited a fast electron transfer process and good electrocatalytic reduction toward H2O2. Under optimum experimental conditions the biosensor linearly responds to H2O2 concentration in the range of 5.0×10−7–1.4×10−4M with a detection limit of 2.0×10−7M (S/N=3). The apparent Michaelis–Menten constant (KappM) of the biosensor is calculated to be 3.75×10−5M, suggesting high enzymatic activity and affinity toward H2O2. In addition, the HRP–Ag@C/ITO bio-electrode shows good reproducibility and long-term stability. Thus, the core–shell structured Ag@C is an attractive material for application in the fabrication of biosensors due to its direct electrochemistry and functionalized surface for efficient immobilization of bio-molecules.

Fabrication of a tunable glucose biosensor based on zinc oxide/chitosan-graft-poly(vinyl alcohol) core-shell nanocomposite

A potentiometrically tuned-glucose biosensor was fabricated using core-shell nanocomposite based on zinc oxide encapsulated chitosan-graft-poly(vinyl alcohol) (ZnO/CHIT-g-PVAL). In a typical experiment, ZnO/CHIT-g-PVAL core-shell nanocomposite containing <20nm ZnO nanoparticles was synthesized using wet-chemical method. The glucose responsive bio-electrode, i.e., glucose oxidase/ZnO/chitosan-graft-poly(vinyl alcohol) (GOD/ZnO/CHIT-g-PVAL/ITO) was obtained by immobilization of glucose oxidase (GOD) onto the electrode made of resulting ZnO core-shell nanocomposite coated on the indium-tin oxide (ITO) glass substrate. The ZnO/CHIT-g-PVAL/ITO and GOD/ZnO/CHIT-g-PVAL electrodes were characterized with Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), whereas ZnO/CHIT-g-PVAL size of core-shell nanoparticles were measured using transmission electron microscopy (TEM). The electrostatic interaction between GOD and ZnO/CHIT-g-PVAL provided the resulting tuned enzyme electrode with a high degree of enzyme immobilization and excellent lifetime stability. The response studies were carried out as a function of glucose concentration with potentiometric measurement. The GOD/ZnO/CHIT-g-PVAL/ITO bioelectrode has showed a linear potential response to the glucose concentration ranging from 2μM to 1.2mM. The glucose biosensor exhibited a fast surface-controlled redox biochemistry with a detection limit of 0.2μM, a sensitivity of >0.04V/μM and a response time of three sec. ZnO/CHIT-g-PVAL core-shell nanocomposite could be a promising nanomaterials for a range of enzymic biosensors.

Polyaniline-CdS Quantum Dots Composite for Mediator Free Biosensing

A novel route has been introduced to fabricate the composite of polyaniline (PANI) and cadmium sulphide quantum dots (CdS-QD) using electrochemical polymerization technique for mediator free biosensing. The synthesis process involves in situ formation of CdS quantum dots that provide template for eletro-polymerization of aniline resulting in nanostructured PANI-(CdS-QD) film deposition on the indium-tin-oxide (ITO) coated glass plate. Transmission electron microscopy and scanning electron microscopy have been used to reveal the formation of CdS-QD and morphological changes involved during incorporation of CdS in PANI matrix and while immobilization of cholesterol oxidase (ChOx). The UV–visible and FT-IR investigations show the formation of PANI-(CdS-QD) composite at the molecular level. This matrix has been utilized for the covalent immobilization of cholesterol oxidase to explore its application for cholesterol sensing. The results of the CV and EIS studies indicate enhanced electrochemical and charge transfer behaviour of the composite. The response studies, carried out using CV technique, reveal this ChOx/ PANI-(CdS-QD)/ITO bioelectrode to detect cholesterol in the concentration range of 50 to 500 mgdL -1 with good detection limit (47.8 mgdL -1 ) and low app m K value (0.82 mM).

Horse radish peroxidase immobilized polyaniline for hydrogen peroxide sensor

AbstractHorse radish peroxidase (HRP) has been electrochemically entrapped into perchlorate (ClO) doped polyaniline (PANI) film deposited onto indium‐tin‐oxide (ITO) coated glass plate. This HRP‐PANI‐ClO/ITO bioelectrode characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), UV‐Visible spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques has been utilized for estimation of hydrogen peroxide (H2O2). This H2O2 sensor exhibits response time of 5 s, linearity from 3 to 136 mM, sensitivity as 0.5638 µA mM−1 cm−2 with linear regression of 0.985. The value of the Michaelis–Menten constant (Km) has been obtained as 1.984 mM. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Electrophoretic Fabrication of Chitosan−Zirconium-Oxide Nanobiocomposite Platform for Nucleic Acid Detection

The present work describes electrophoretic fabrication of nanostructured chitosan-zirconium-oxide composite (CHIT-NanoZrO(2)) film (180 nm) onto indium-tin-oxide (ITO)-coated glass plate. This nanobiocomposite film has been explored as immobilization platform for probe DNA specific to M. Tuberculosis as model biomolecule to investigate its sensing characteristics. It is revealed that pH-responsive behavior of CHIT and its cationic skeleton is responsible for the movement of CHIT-NanoZrO(2) colloids toward cathode during electrophoretic deposition. The FT-IR, SEM, TEM, and EDX techniques have been employed for the structural, morphological, and composition analysis of the fabricated electrodes. The morphological studies clearly reveal uniform inter-linking and dispersion of hexagonal nanograins of ZrO(2) (30-50 nm) into the chitosan matrix, resulting in homogeneous nanobiocomposite formation. Electrochemical response measurements of DNA/CHIT-NanoZrO(2)/ITO bioelectrode, carried out using cyclic voltammetry and differential pulse voltammetry, reveal that this bioelectrode can specifically detect complementary target DNA up to 0.00078 μM with sensitivity of 6.38 × 10(-6) AμM(-1).

Electrophoretically deposited polyaniline nanotubes based film for cholesterol detection

Polyaniline nanotube (PANI-NT) based films have been fabricated onto indium-tin-oxide (ITO) coated glass plates via electrophoretic technique. These PANI-NT/ITO electrodes have been utilized for covalent immobilization of cholesterol oxidase (ChOx) using glutaraldehyde (Glu) as cross-linker. Structural, morphological and electrochemical characterization of PANI-NT/ITO electrode and ChOx/Glu/PANI-NT/ITO bioelectrode have been done using FT-IR spectroscopy, SEM, electrochemical impedance spectroscopy and cyclic voltammetry techniques. Response studies of the ChOx/Glu/PANI-NT/ITO bioelectrode have been carried out using both linear sweep voltammetry and UV-Visible spectrophotometry. The results of the biosensing studies reveal that this bioelectrode can be used to detect cholesterol in wide detection range of 25-500 mg/dL with high sensitivity of 3.36 mA mg(-1) dL and fast response time of 30 s at pH 7.4. This bioelectrode exhibits very low value of Michaelis-Menten constant of 1.18 mM indicating enhanced interactions between cholesterol and ChOx immobilized onto this nanostructured PANI matrix.

Peptide Nucleic Acid Immobilized Biocompatible Silane Nanocomposite Platform for Mycobacterium tuberculosis Detection

AbstractWe have prepared nanocomposite films comprising of 3‐glycidoxypropyltrimethoxysilane (GOPS) and iron‐oxide (Fe3O4) onto indium‐tin‐oxide (ITO) glass plate for covalent immobilization of 21‐mer peptide nucleic acid (PNA). These films have been characterized using contact angle, atomic force microscopy (AFM), electrochemical techniques. The electrochemical response of the GOPS/ITO and Fe3O4‐GOPS/ITO electrodes has been investigated by hybridization with complementary, non‐complementary and one‐base mismatch using methylene blue as electrochemical indicator. The PNA/Fe3O4‐GOPS/ITO bioelectrode exhibits improved specificity and detection limit (0.1 fM) as compared to that of the PNA‐GOPS/ITO bioelectrode (0.1 pM). This PNA/Fe3O4‐GOPS/ITO electrode can be utilized for detection of hybridization with the complementary sequence in sonicated M. tuberculosis genomic DNA within 90 s of hybridization time.

Polyaniline/Single‐Walled Carbon Nanotubes Composite Based Triglyceride Biosensor

AbstractNanocomposite film comprising of polyaniline (PANI) and single walled carbon nanotubes (SWCNT) has been fabricated onto indium‐tin‐oxide (ITO) coated glass plate using electrophoretic technique. Co‐immobilization of glycerol dehydrogenase (GDH) and lipase (LIP) has been done via N‐ethyl‐N′‐(3‐dimethylaminopropyl) carbodiimide and N‐hydroxysuccinimide chemistry to explore its application for triglyceride (tributyrin) sensing. Response studies have been done using linear sweep voltammetry revealing that LIP‐GDH/PANI‐SWCNT‐TB/ITO bioelectrode can detect tributyrin in the range of 50 to 400 mg dL−1 with low Michaelis–Menten constant of 1.138 mM, improved response time of 12 s, high sensitivity as 4.28×10−4 mA mg−1 dL and storage stability of about 13 weeks.

Polyaniline nanotubes for impedimetric triglyceride detection

Polyaniline nanotubes (PANI-NT) based film electrophoretically deposited onto indium–tin–oxide (ITO) coated glass plate has been utilized for covalent immobilization of lipase (LIP), via glutaraldehyde (Glu), for triglyceride detection using impedimetric technique. It is shown that fatty acid molecules produced during triglyceride hydrolysis result in change in charge transfer resistance ( R CT) of PANI-NT film with varying triglyceride concentration. LIP/Glu/PANI-NT/ITO bioelectrode has linearity as 25–300 mg dL −1, sensitivity as 2.59 × 10 −3 KΩ −1 mg −1 dL, response time as 20 s and regression coefficient as 0.99. A low value of apparent Michaelis–Menten constant (∼0.62 mM) indicates high enzyme affinity to tributyrin. The LIP/Glu/PANI-NT/ITO bioelectrode has been utilized to estimate triglyceride in serum samples.

Nucleic acid sensor for insecticide detection

Nucleic acid sensor based on polyaniline (PANI) has been fabricated by covalently immobilizing double stranded calf thymus (dsCT) DNA onto perchlorate (ClO(-) (4))-doped PANI film deposited onto indium-tin-oxide (ITO) glass plate using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) chemistry. These dsCT-DNA-PANI-ClO(4)/ITO and PANI-ClO(4)/ITO electrodes have been characterized using square wave voltammetry, electrochemical impedance, scanning electron microscopy (SEM) and Fourier-transform-infrared (FTIR) measurements. This disposable dsCT-DNA-PANI-ClO(4)/ITO bioelectrode, stable for about 4 months, can be used to detect cypermethrin (0.005 ppm) and trichlorfon (0.01 ppm) in 30 and 60 s, respectively.