Investigation On Electrochemical Biosensors Based On Three Types Of Composite Nanomaterials

Nowadays the construction of novel electrochemical biosensor with high sensitive and selective sensing interface based on new nanomaterials and nanocomposite has become one of the research subjects for analysts. In this thesis, three types novel hydrogen peroxide biosensor were fabricated based on three types of nanocomposite, which was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, chronoamperometry and scanning electron micros copy. After which the electrochemical behaviors of redox protin (enzyme) were studied in details and the new methods for determination of H2O2 were developed. These studies enriched the study of biological electroanalytical chemistry, expanding the scope of the application of nanocomposites. The thesis was divided into three chapters and presented as follows:1. A review on the eleetroehemieal sensor and its researeh progress was presented with 113 referenees.2. A hydrogen peroxide biosensor based on nanoCaCO3 was fabricated and the direct electrochemistry and electrocatalysis of Hb at the electrode was investigated. The results showed that the biosensor displayed a pair of well defined redox peaks with the formal potential (E0') of-0.295 V. The electron transfer rate constant (ks) was estimated to be 1.98 s-1. The biosensor also exhibited excellent electrocatalytic activity to H2O2. The linearity range for determination of H2O2 is from 5.0x10-6 to 1.3×10-3mol·L-1, with a sensitivity of 0.16 AM-1cm-2 and a detection limit of 1.6×10-6mol·L-1. The apparent Michaelis-Menten constant was calculated to be 8.1×10-4mol·L-1.3. A Hydrogen peroxide biosensor based on PS-MWCNT composite was fabricated and the direct electrochemistry and electrocatalysis of HRP at the electrode was investigated. The results showed that the biosensor displayed a pair of well defined redox peaks with the formal potential (E0') of-0.400 V. The electron transfer rate constant (ks) was estimated to be 1.15s-1 The biosensor also exhibited excellent electrocatalytic activity to H2O2. The linearity range for determination of H2O2 is from 5.0×10-7 to 8.2×10-4mol·L-1 with a detection limit of 1.6×10-7 mol·L-1. The apparent Michaelis-Menten constant was calculated to be 6.64×10-4mol·L-1.4. A Hydrogen peroxide biosensor based on Fe3O4 and SiO2 nanomaterials was fabricated and the direct electrochemistry and electrocatalysis of Hb at the electrode was investigated. The results showed that the biosensor displayed a pair of well defined redox peaks with the formal potential (E0') of-0.195 V. The electron transfer rate constant (ks) was estimated to be 1.54 s-1. The biosensor also exhibited excellent electrocatalytic activity to H2O2. The response time is lower than 2s; the linearity range for determination of H2O2 is from 1.0×10-7 to 1.7×10-3 mol·L-1 with a detection limit of 3.3×10-8 mol·L-1. The apparent Michaelis-Menten constant was calculated to be 8.12×10-4 mol·L-1. Compare with other two hydrogen peroxide biosensor, this biosensor has the Characteristics like high sensitivity, wide linear range and good selectivity.