Fabrication Of A Novel Layer-by-layer Film Based Glucose Biosensor With Conducting Polymer And Nanomaterials

At present, diabetes is one of the diseases to harm the human health and affecting people's common life. It's very important to control the glucose concentration from food intake. Therefore, the establishment of a rapid, efficient, low-cost method of glucose testing in food industry is necessary. Many reseachers take more attentions to the conducting polymers, because of they have high conductivity at room temperature, larger surface area and the light proportion. Carbon nanotubes has large surface area and specific physical properties, they were both widely used on the development of biological sensors. This paper selects different conductive polymers and carbon nanotubes to develop different electrochemical glucose biosensor. The performance, optimization, real samples test of the proposed biosensor was studied.The paper consists the following parts:1. A novel glucose biosensor was developed, based on the immobilization of glucose oxidase (GOD) on a Pt electrode, which was modified with poly(allylamine) (PAA)/poly(sodium 4-styrenesulfonate) (PSS) and gold nanoparticles (GNPs) decorated Pb nanowires (PbNWs). PAA and PSS were alternately deposited on the cleaned Pt electrode surface (PSS/PAA/Pt). The PSS/PAA/Pt electrode was alternately immersed in GNPs/PbNWs and GOD to assemble different layers of multilayer films. The effect of pH and temperature on the sensitivity of the biosensor was studied in detail. Under the optimized conditions, the biosensor showed the detection limit of 0.05 mmol/L, and the response time <5 s with a linear range of 0.1-6.0 mmol/L. Furthermore, the biosensor exhibited good reproducibility, long-term stability (90% remains after 4 weeks) and relative good anti-interference.2. A glucose biosensor comprising the glucose oxidase, horseradish peroxidase (HRP) systems and polypyrrole (PPY)/titanium dioxide (TiO₂) nano-composites has been successfully developed. The PPY/TiO₂ nano-composites can increase the current signals, the GOD/HRP systems can improve the sensitivity of the glucose biosensor. The resulting biosensor exhibited a fast response time (within 6 s) and a wider linear calibration range from 0.04 to 4.2 mmol/L with a detection limit of 0.3μmol/L glucose (S/N=3). With the low operating potential, the biosensor showed an excellent selectivity. The proposed biosensor was successfully applied to determine the glucose content in real samples such as juice and tea drink. The glucose recovery test demonstrated that the proposed glucose biosensor offers an excellent determination of glucose in real samples.3. A novel amperometric glucose biosensor based on the composite film composed of GOD, prussian blue (PB), poly(o-aminophenol) (POAP), and polyaniline (PANI) was developed for the specific detection of glucose. POAP film at PB modified platinum electrode. The conducting ability of POAP/PANI was better than one of them's conducting ability. The components in the nanocomposite provide adequate electron transfer path between GOD and the electrode. Effects of the biosensor response of parameters such as working potential, pH, temperature, and loaded, enzyme were investigated and discussed. The resulting biosensor exhibited a fast response time (within 6 s) and a wider linear calibration range from 0.25 to 50 mmol/L with a detection limit of 0.005 mmol/L glucose (S/N=3). Additionally, the biosensor shows good anti-interferent ability. Excellent and stability of biosensor are also observed.4. A glucose biosensor comprising chitosan (CS) /multi-wall carbon nanotubes(MWNTs), PPY/TiO₂ and GOD-immobilized was successfully developed. Uniform dispersion of TiO₂ in PPY matrix improved the PPY conductivity and leaded to high rate capability in CS/MWNTs/PPY/TiO₂. Electrochemical measurements were conducted to reveal the electroactivity of the GOD on the modified Pt electrode. The bilayer CS/MWNTs and PPY/TiO₂ served as a good carrier for GOD as well as a conductor, enhancing greatly the response current. The GOD immobilized in this way retained its bioelectrocatalytic activity for the oxidation of glucose. The biosensor showed linear response to glucose from 6.2×10^-6 to 1.0×10^-3 mol/L with a detection limit of 3.5×10^-6 mol/L (S/N=3). The effect of pH and applied potential of the biosensor was studied in detail. The biosensor exhibited fast response time (5 s) and storage stability (90% of initial sensitivity after one month storage). Finally, the proposed sensor was successfully applied and checked in the glucose determination in real samples.5. A new class of glucose biosensor with high sensitivity and selectivity is described. GOD has been immobilized PPY, MWCNTs and GNPs biocomposite to fabricate a glucose biosensor. The amperometric responses were correlated linearly with the concentration of glucose over the range of 5μmol/L-12 mmol/L and the detection limit was 0.1μmol/L. The relative standard deviation (RSD) for the determination of 0.05 mmol/L glucose was 4.8%. It still kept 95% activity after 10 days. This biosensor exhibited a good anti-interferential quality and an excellent stability. It has a great improvement in sensitivity and selectivity for glucose analysis. The proposed biosensor was successfully applied to determine the glucose content in real samples such as juice and tea drink.