Study On Amperamatric Hydrogen Peroxide Biosensor

Biosensor, which is a cross science based on biology, iatrology, physics, chemistry and electronic technology. With the advantages including high-sensitivity, low-cost, selectivity, biosensors have been not only widely used in clinical, chemical analysis, zymolysis, food quality control and environmental control, but also for the analysis of the living object. However, during the fabrication of biosensors, the immobilization of biorecognition molecule is still an active research topic, and also a key factor for the stability, sensitivity, selectivity of the biosensor. Therefore, this thesis involves the follwing subjects relating to amperometric hydrogen peroxide biosensors based on different immobilization methods and electrochemical methods. The thesis is described as follows:(1) A new approach to construct a hydrogen peroxide biosensor was described. Thionine was electropolymerized on the platinum electrode to form a negatively charged surface by the method of cyclic voltammetry. Then HRP/nano-Au/HRP were immobilized on the electrode modified by poly(thionine) by electrostatic adsorption to prepare the hydrogen peroxide biosensor. The results obtained showed that the biosensor exhibited fast response, high sensitivity and fine stability. The linear response of the sensor to hydrogen peroxide was in the concentration range of 5.2×10^-7～2.0×10^-3 mol/L with a detection limit of 1.7x10^-7 mol/L. In the meantime the low operating potential of the biosensor could effectively eliminate interference from common interferents, such as ascorbic acid and uric acid.(2) A novel hydrogen peroxide biosensor was fabricated for the determination of H₂O₂. The precursor film was first electropolymerized on the glassy carbon electrode with p-aminobenzene sulfonic acid (p-ABSA) by cyclic voltammetry (CV). Then thionine (Thi) was adsorbed to the film to form a composite membrane, which yielded an interface containing amine groups to assemble gold nanoparticles (nano-Au) layer for immobilization of horseradish peroxidase (HRP). The electrochemical characteristics of the biosensor were studied by CV and chronoamperometry. The factors influencing the performance of the resulting biosensor were studied in detail. The biosensor responded to H₂O₂ in the linear range from 2.6x10^-6 mol/L to 8.8×10^-3 mol/L with a detection limit of 6.4x10^-7 mol/L. Moreover, the studied biosensor exhibited good accuracy, high sensitivity. The proposed method was economical and efficient, making it potentially attractive for the application to real sample analysis.(3) A new hydrogen peroxide biosensor has been contrived. First, Lcysteine(L-cys) was immobilized on the gold electrode by self-assembling. Then Hb/nano-Au/PDDA was immobilized on the modified electrode by electrostatic adsorption to prepare the hydrogen peroxide biosensor. The performance of the resulting biosensor was studied in detail by means of CV and chronoamperometry. The results obtained showed that the biosensor exhibited fast response and fine stability. The linear response of the sensor to hydrogen peroxide was in the concentration range of 4.2×10^-7～3.0x10^-3 mol/L with a detection limit of 1.4×10^-7 mol/L. In the meantime the low operating potential of the biosensor could effectively eliminate interference from common interferents, such as ascorbic acid and uric acid.(4) A novel hydrogen peroxide biosensor was fabricated by self-assembling of Hemoglobin (Hb), gold nanoparticles (nano-Au) and L-cysteine (L-cys) on the precursor film formed by electropolymerization of p-aminobenzene sulfonic acid (p-ABSA) on the platinum disk electrode. Electrochemical impedance spectroscopy (EIS) and UV-vis absorption spectroscopy were employed to characterize the modified process. The performance and factors influencing the resulting biosensor were studied in detail by means of CV and chronoamperometry. The immobilized Hb exhibited direct electrochemical behavior toward the reduction of hydrogen peroxide (H₂O₂). And the linear range to H₂O₂ was from 2.1×10^-7 to 3.1×10^-3 mol/L with a detection limit of 7.0×10^-8 mol/L (S/N=3). In addition, the studied biosensor exhibited good accuracy, high sensitivity.