| Electrochemical sensor is quite unique, because it combines the enzyme specificity with the sensitivity and convenience of electroanalytical techniques in a compact form to facilitate analysis. In this paper, the nanoparticles were used in the fabrication of biosensors. This thesis concerns two research sections:First, a one-step method for fabrication of horseradish peroxidase (HRP) biosensor with Au nanoparticle (AuNP) has been developed. The AuNP and HRP were simultaneously embedded in silica sol-gel network on gold electrode surface in the presence of cysteine. The immobilized HRP exhibited direct electrochemical behavior toward the reduction of hydrogen peroxide. The heterogeneous electron transfer rate constant was evaluated to be 7.8s-1. The biosensor displayed an excellent electrocatalytic response to the reduction of H2O2 without any mediator. The calibration range of H2O2 was from 1.6μmol L-1 to 3.2 mmol L-1 and a detection limit of 0.5μmol L-1 at a signal-to-noise ratio of 3. The KMapp value of HRP immobilized on the electrode surface was found to be 1.1 mmol L-1. The biosensor exhibited high sensitivity, rapid response and long-term stability.Second, carbon nanotube (CNT) was used in the fabrication of Xanthine oxidase (XOD) biosensor. XOD/CNT/GC electrode was fabricated. The influences of CNT, pH and scan rate to the electrode were discussed. The XOD exhibited direct electrochemical behavior with the function of CNT. The heterogeneous electron transfer rate constant was evaluated to be 2.0 s-1. The calibration range of xanthine (XA) was from 0.1μmol L-1 to 1.0μmol L-1 and a detection limit of 80 nmol L-1 at a signal-to-noise ratio of 3. The KMapp value of XOD immobilized on the CNT was found to be 0.05 mmol L-1. The biosensor exhibited high sensitivity, rapid response. It was found the response current to XA decreased about 4% after storage at 4°C for 14 days. In order to improve the stability of enzyme electrode, sol-gel was applied to the... |
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