Sarcosine Oxidase Encapsulated Polyvinyl Alcohol-Silica-AuNP Hybrid Films for Sarcosine Sensing Electrochemical Bioelectrode (original) (raw)
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Analytical Chemistry, 2013
An amperometric glucose enzyme electrode was developed by the immobilization of glucose oxidase (GOD) in a composite material based on polyvinyl alcohol (PVA) and partially prehydrolyzed tetraethyl orthosilicate (pphTEOS) on the surface of "in-house" fabricated graphite electrodes. For comparison, silver and gold nanoparticles (Ag/AuNPs) embedded in the PVA-pphTEOS matrix was prepared through a novel method via sol−gel process based on the in situ chemical reduction of Ag or Au ions using PVA as a reducing agent and stabilizer. The successful incorporation of Ag and AuNPs ranging from 5 to 7.5 and 4.5−11 nm, respectively, in the PVA-pphTEOS matrix was confirmed by UV−vis spectroscopy, TEM, and EDX analysis. The PVA-TEOS matrix was also characterized by FTIR spectroscopy. The analytical performance of the enzyme electrodes were studied in terms of linear ranges, sensitivities, response times, limits of detection, reproducibility and stability.
Electrochimica Acta, 2006
Sol-gel encapsulated glucose oxidase (GOx) enzyme electrodes based on carbon film resistors with chemically deposited copper hexacyanoferrate (CuHCF) or poly(neutral red) (PNR), made by electrochemical polymerisation, as redox mediator have been developed and characterised using cyclic voltammetry, electrochemical impedance spectroscopy and atomic force microscopy. The sol-gel was prepared using three different trioxysilanes: 3aminopropyl-triethoxysilane (APTOS), 3-glycidoxypropyl-trimethoxysilane (GOPMOS) and methyltrimethoxysilane (MTMOS), without alcohol addition, and alcohol formed during the hydrolysis of the precursor compounds was removed. The best sensitivity, ∼60 nA mM −1 , for glucose and limit of detection (2-40 M, depending on the sol-gel precursor) were obtained when PNR was used as a mediator, but the linear range (50-600 M) was two to four times lower than that at CuHCF mediated biosensors, using an operating potential of +0.05 V at CuHCF or −0.25 V versus saturated calomel electrode (SCE) at PNR mediated electrodes. The stability of the sensor depended on the sol-gel morphology and was 2 months testing the biosensor every day, while the storability was at least 4 months in the case of GOPMOS, the sensors being kept in buffer at +4 • C.
Human sulfite oxidase electrochemistry on gold nanoparticles modified electrode
Bioelectrochemistry, 2012
The present study reports a facile approach for sulfite biosensing, based on enhanced direct electron transfer of a human sulfite oxidase (hSO) immobilized on a gold nanoparticles modified electrode. The spherical core shell AuNPs were prepared via a new method by reduction of HAuCl 4 with branched poly(ethyleneimine) in an ionic liquids resulting particles with a diameter less than 10 nm. These nanoparticles were covalently attached to a mercaptoundecanoic acid modified Au-electrode where then hSO was adsorbed and an enhanced interfacial electron transfer and electrocatalysis was achieved. UV/Vis and resonance Raman spectroscopy, in combination with direct protein voltammetry, are employed for the characterization of the system and reveal no perturbation of the structural integrity of the redox protein. The proposed biosensor exhibited a quick steady-state current response, within 2 s, a linear detection range between 0.5 and 5.4 μM with a high sensitivity (1.85 nA μM − 1). The investigated system provides remarkable advantages in the possibility to work at low applied potential and at very high ionic strength. Therefore these properties could make the proposed system useful in the development of bioelectronic devices and its application in real samples.
Analytical and Bioanalytical Chemistry, 2008
Protective polymer coatings have been used to enhance the retention of enzymes in sol-gel films as immobilisation phases in electrochemical biosensors. Carbon film electrodes were electrochemically modified with poly(neutral red) (PNR). These electrodes were coated with oxysilane sol-gels incorporating glucose oxidase and an outer coating of carboxylated PVC (CPVC) or polyurethane (PU), with and without Aliquat-336 or isopropyl myristate (IPM) plasticizer, was applied. The biosensors were characterised electrochemically using cyclic voltammetry and amperometry, electrochemical impedance spectroscopy and scanning electron microscopy. Impedance spectra showed that the electrode surface is most active when the sol-gel-GOx layer is not covered with a membrane. However, membranes without plasticizer extend the lifetime of the biosensor to more than 2 months when PU is used as an outer membrane. The linear range of the biosensors was found to be 0.05-0.50 mM of glucose and the biosensor with PU outer membrane exhibited higher sensitivity (ca.117 nA mM −1 ) in the region of linear response than that with CPVC. The biosensors were applied to glucose measurement in natural samples of commercial orange juice.
Enzyme and microbial technology, 2018
An amperometric sarcosine biosensor was fabricated based on covalent immobilization of sarcosine oxidase (SarOx) onto the nanocomposite of carboxylated multi-walled carbon nanotubes (cMWCNT)/chitosan (CHIT) and copper nanoparticles (CuNPs), electrodeposited on gold (Au) electrode. The SarOx/CHIT/CuNPs/c-MWCNT/Au electrode was characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The enzyme electrode exhibited optimum current within 2 s at a potential of 0.2 V against Ag/AgCl, pH 7.0 and 35 °C. A linear relationship was obtained between sarcosine concentration in the range, 0.1-100 μM and current (mA) under optimum conditions. The biosensor exhibited a high sensitivity of 277.5 μA/μM/cm, a low detection limit of 0.1 pM and excellent storage stability (180 days). The analytical recoveries of added sarcosine in sera at 0.5 μM and at 1.0 μM concentration were 95.5% and 97.30 respectively. The precision i.e. within ...
2013
In this thesis, the research work was focused on the immobilization of different enzymes (oxidases and dehydrogenases) into biocomposite silica matrix with the aim of amperometric biosensors construction. Then, the structured nanomaterials were introduced in the system in order to improve the characteristics of biosensors. The method of electrochemically-assisted deposition was chosen for the immobilization of enzymes on the surface of nanomaterials as it provides possibility of fine tuning of film thickness allowing covering each individual nanoobject. The feasibility of this was shown while modifying the platinum nanofibers, which demonstrate high electroactive surface and H2O2 oxidation rate, with silica-glucose oxidase biocomposite. The electrochemically-assisted deposition also allows the express modification of gold screen-printed electrodes with silica-choline oxidase biocomposite making possible the quick fabrication of cheap choline biosensors with high analytical character...
Enzyme and Microbial …, 2013
A novel electrochemical biosensor for the determination of pyrogallol (PG) and hydroquinone (HQ) has been constructed based on the poly l-arginine (poly(l-Arg))/carbon paste electrode (CPE) immobilized with horseradish peroxidase (HRP) and silver nanoparticles (AgNPs) through the silica sol-gel (SiSG) entrapment. The electrochemical properties of the biosensor were characterized by employing the electrochemical techniques. The proposed biosensor showed a high sensitivity and fast response toward the determination of PG and HQ around 0.18 V. Under the optimized conditions, the anodic peak current of PG and HQ was linear with the concentration range of 8 M to 30 × 10 −5 M and 1-150 M. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 6.2 M, 20 M for PG and 0.57 M, 1.92 M for HQ respectively. The electrochemical impedance spectroscopy (EIS) studies have confirmed that the occurrence of electron transfer at HRP-SiSG/AgNPs/poly(l-Arg)/CPE was faster. Moreover the stability, reproducibility and repeatability of the biosensor were also studied. The proposed biosensor was successfully applied for the determination of PG and HQ in real samples and the results were found to be satisfactory.
Acta Biomaterialia, 2005
The determination of creatinine levels in biological fluids is an increasingly important clinical requirement. Amperometric biosensors have been developed based on a three-enzyme system which converts creatinine to amperometrically measurable hydrogen peroxide. The development of the amperometric creatinine biosensor has been slow due the complexity of the three-enzyme system. This paper, the first of three, discusses the chemical modification of sarcosine oxidase and the immobilization and stabilization of this enzyme using polyurethane prepolymers. Sarcosine oxidase was completely inactivated after modification using poly(ethylene glycol) activated with isocyanate. The addition of a competitive inhibitor during enzyme modification was effective in protecting the enzyme from inactivation. Computational analysis of the structure of sarcosine oxidase suggests that there is a lysine in the active site that may be hyper-reactive. The enzyme was irreversibly immobilized using polyurethane prepolymers and retained significant activity. The enzymeÕs half-life at 37°C increased from seven days to more than 50 days after immobilization.
Journal of Analytical Chemistry, 2015
Modification of carbon and gold electrodes by a biocomposite film based on silica, hemoglobin (Hb), and glucose oxidase (GOx) has been performed by electro assisted deposition using an electrogener ated catalyst. Proteins immobilized in the film retain catalytic activity for three weeks. The stability of the analytical signal of a modified electrode significantly increases on the addition of Au nanoparticles of the diameter 20 nm and cetyltrimethylammonium bromide (20 CMC) to the sol. A gold electrode modified with a biocomposite SiO 2-Hb-GOx-Au film has been used for the voltammetric determination of glucose in model solutions and porcine blood serum. The calibration curve is linear in the range 0.015-0.20 mM; the limit of detection is 0.008 mM of glucose. The developed method of modification offers promise for the prep aration of sensing elements of two enzyme amperometric biosensors.