Prolonging Glucose Sensor’s Performance in In Vivo Environment (original) (raw)
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Application of sol gel technique for glucose oxidase immobilization in biosensor application
A sol gel based biosensor using 3-glycidoxypropyl dimethylethoxysilane, as a silane agent was developed as a novel method for biosensor enzyme immobilization. The key materials applied were tetra methyl orthosilicate (TMOS), and the cross link agent, 3-Glycidoxypropyl dimethylethoxysilane, (GDP). Three compositions with different amount of GDP and glucose oxidase were experimented with the amount of TMOS was kept constant. The first coating consisted of 2mg of glucose oxidase and 20μl of GDP. The second trial involved higher GDP composition which is 100μl. The final trial applied higher content of glucose oxidase which is 12 mg with 20μl of GDP. The result showed that sensors with high composition of crosslink agent coating was capable to exhibit reliable glucose detection. The crosslink agent insufficiency in the first composition failed to provide good attachment for the enzyme on the electrode. Thus, the test was halted after few readings due to the inability of the sensor to detect glucose increment. For the high amount glucose oxidase composition, failure happened due to the deficiency of GDP to retain the enzyme thus contributed to the glucose oxidase leaching. We conclude that adequate amount of crosslink agent is vital for a sol gel based biosensor to function successfully.
Journal of the Chilean Chemical Society
In this study, an electrochemical biosensor was developed by using a sol-gel coating solution. The modified platinum electrode used in the study was constructed by immobilization of glucose oxidase under a layer of sol-gel film. The sol-gel coating solution was prepared by using GLYMO, TEOS, and MTEOS. Electrochemical measurements were carried out amperometrically by determining hydrogen peroxide produced by the enzymatic reaction between glucose and glucose oxidase. The amperometric responses of the resulting enzymatic electrode to glucose were rapid. It was observed that the amperometric response of the enzymatic electrode was linear for glucose concentrations in the range from 2 to18 mM with 50 s response time. LOD and LOQ for the enzymatic electrode were calculated to be 0.055 mM and 0.184 mM, respectively. It was determined that the developed biosensor had an acceptable reproducibility. The selectivity of the biosensor was determined in the presence of some interfering substanc...
Biosensors & Bioelectronics, 2004
An important requirement of immobilized enzyme based biosensors is the thermal stability of the enzyme. Studies were carried out to increase thermal stability of glucose oxidase (GOD) for biosensor applications. Immobilization of the enzyme was carried out using glass beads as support and the effect of silane concentration (in the range 1–10%) during the silanization step on the thermal stability of GOD has been investigated. Upon incubation at 70 °C for 3 h, the activity retention with 1% silane was only 23%, which increased with silane concentration to reach a maximum up to 250% of the initial activity with 4% silane. Above this concentration the activity decreased. The increased stability of the enzyme in the presence of high silane concentrations may be attributed to the increase in the surface hydrophobicity of the support. The decrease in the enzyme stability for silane concentrations above 4% was apparently due to the uneven deposition of the silane layer on the glass bead support. Further work on thermal stability above 70 °C was carried out by using 4% silane and it was found that the enzyme was stable up to 75 °C with an increased activity of 180% after 3-h incubation. Although silanization has been used for the modification of the supports for immobilization of enzymes, the use of higher concentrations to stabilize immobilized enzymes is being reported for the first time.
Development of Glucose Biosensor by Using Gelatin and Gelatin-Polyacrylamide Supporting Systems
Artificial Cells, Blood Substitutes, and Biotechnology, 2006
In this work an amperometric glucose biosensor based on surface immobilization method was developed. Glutaraldehyde was used as cross-linker to establish the immobilization of glucose oxidase onto gelatin (carrier=coating reagent). In order to increase the porosity of coating material, immobilization media was further treated by polyacrylamide. Although this treatment increased the performance of biosensor to a large extent with respect to current densities obtained, it negatively affected the long-term stability. Our biosensor showed linear response in the physiological range of blood glucose (0.05 to 6 mM), had an acceptable response time (60 seconds) and was stable for 17 repeated usages in 51 days. We obtained best results with pH values very close to physiological pH and our biosensor could work efficiently in the tested temperature range 15 to 65 C.
Spectroscopy, 2005
A spectrophotometric method is presented to determine glucose employing the sol-gel technique. Myoglobin (Mb) and glucose oxidase are encapsulated in a transparent and porous silica glass. The produced gel (xerogel) is then immersed in water where increments of glucose are added to the solution with stirring; glucose diffuses into the sol-gel glass pores and a series of reactions take place. Glucose is first oxidized by glucose oxidase and oxygen to gluconate and hydrogen peroxide is generated. The liberated hydrogen peroxide oxidizes the Mb heme (Fe2+into Fe3+). The higher is the glucose concentration added, the more is the H2O2generated, and the more is the Mb oxidation (Fe2+to Fe3+) and as a result the higher is the absorbance at 400 nm (negative peak, lower absorbance value). All measurements are performed at this wavelength (400 nm), the negative peak obtained by subtracting the absorption spectra of Mb before and after oxidation. Measuring the slope of the absorbance decay ver...
Electroanalysis, 2013
This paper describes the development and optimization of an amperometric bienzymatic biosensor for glucose, based on glucose oxidase (GOX) and peroxidase (HRP), immobilized on mesoporous silica with hexagonal symmetry (MCM-41). The mesoporous material was immobilized by Nafion assisted adsorption on a glassy carbon electrode, which was used as working electrode. Measurements were performed in a conventional three electrode cell using a Ag/AgCl reference electrode and platinum wire as counter electrode. Operating parameters such as GOX/ HRP enzyme ratio, mediator (catechol) concentration, applied potential and pH were optimized. The proposed biosensor showed excellent analytical performance with detection and quantification limits of 8.6 10 À6 M and 2.5 10 À5 M, respectively; analytical sensitivity of 4.67 10 À4 AM À1 , repeatability < 5 % RSD and a long-term stability of 10 days (5 daily measurements). Also, five possible interferences were studied and only ascorbic acid showed an amperometric signal, which can be removed with 5 % iodine pretreatment. The biosensor was successfully tested for glucose determination in pharmaceutical formulations, and compared well with an established commercial photometric enzymatic kit (Megazyme).
A new polymer composition was developed based on hybrid sol gel material for the immobilization of enzymes on the surface of screen printed carbon electrodes modified with Prussian blue. The existing and developed methods for the glucose oxidase (GO) immobilization are compared. Highly stable bioelectrodes were shown to be obtained by enzyme immobilization on a hybrid composition consisting of sol-gel/poly vinyl alcohol (PVA) (up to 60 sequential chains) and agar gel (up to 45 sequential chains). The range of glucose concentrations detected during enzyme immobilization in a hybrid sol gel/PVA composition or agar gel without dilution of a sample was 1.0–5.9 μM and 3.6–6.3 μM, respectively. An analysis of wine products was conducted. The results obtained using the proposed biosensors were shown to differ insignificantlyfrom those obtained by high performance liquid chromatography (the correlation coefficient was 0.9998).
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.
A low cost, easy to fabricate, simple to operate, portable and disposable biosensor based upon the enzyme glucose oxidase (GOD) has been developed. A polymer matrix of Polyethylenemine (PEI) and Poly Carbamoylsulphonate (PCS) hydrogel has been used for the immobilization of GOD on a Platinum (Pt) tip of a screen printed graphite electrode. A multi channel potentiostat has been utilized in the electrode configuration for the amperometric measurement of glucose. The developed Pt/PCS+PEI/GOD glucose biosensor system could offer a reliable method of glucose determination in standard stock solutions. The designed glucose bio-sensor system has been duly characterized and the results obtained are presented. The biosensor has been found to show a sensitivity of 0.72 ± 0.15 nA/µM. Also, the specificity of the enzyme electrode and the storage stability of the GOD based biosensor system have been studied. The sensor system has also been tested with the real samples of fruit juice, soft drink and human blood. The biosensor system has been found to possess a potential for food analysis and clinical utility.
Glucose oxidase enzyme immobilized porous silica for improved performance of a glucose biosensor
High activity of glucose oxidase (GOD) enzyme (immobilized in porous silica particles) is desirable for a better glucose biosensor. In this work, effect of pore diameter of two porous hosts on enzyme immobilization, activity and glucose sensing was compared. The hosts were amine functionalized: (i) microporous silica (NH 2 -MS) and (ii) mesoporous silica (NH 2 -SBA-15). Based on whether the dimension of GOD is either larger or smaller than the pore diameter, GOD was immobilized on either external or internal surface of NH 2 -MS and NH 2 -SBA-15, with loadings of 512.5 and 634 mg/g, respectively. However, GOD in NH 2 -SBA-15 gave a higher normalized absolute activity (NAA), which led to an amperometric sensor with a larger linear range of 0.4-13.0 mM glucose. In comparison, GOD in NH 2 -MS had a lower NAA and a smaller linear range of 0.4-3.1 mM. In fact, the present GOD-NH 2 -SBA-15 electrode based sensor was better than other MS and SBA-15 based electrodes reported in literature. Thus, achieving only a high GOD loading (as in NH 2 -MS) does not necessarily give a good sensor performance. Instead, a host with a relatively larger pore than enzyme, together with optimized electrode composition ensures the sensor to be functional in both hyper-and hypoglycemic range.