Synthesis Of Conducting Polymers And Biosensor Research

1. Studies on Synthesis and properties of uniform and Ordered Polyaniline Nanoparticles in the Magnetic FieldIn this paper, the uniform and ordered polyaniline nanoparticles with the average diameter about 95 nm were electropolymerized in solution containing 0.2 mol dm^-3 aniline and 1.2 mol dm^-3 HCl using the method of constant potential at 0.7 V in the presence of magnetic field (780 mT). Effects of the material of substrate and time on properties of polyaniline film were investigated. The experimental results show the magnetic field has orientation effect on aniline polymerization. Distinct scanning electron microscope (SEM) morphologies show polyaniline nanoparticles can be formed in the presence of the magnetic field. The CV and AC impedance results indicate the magnetic field makes the polymer film redox current larger and the charge transfer resistance (Rct) smaller. The nanoparticles were characterized by FTIR spectra, UV-Vis spectra.2. Selective Uricase Biosensor Based on Polyaniline Synthesized in Ionic LiquidThe selective uricase biosensor prepared with electroactive polyaniline (PANI) at high pH is firstly reported in this paper. Effects of electroactive interferents, such as acetaminophen, glutathione, l-cysteine and ascorbic acid on the current response of PANI-uricase biosensor were examined in the presence of their physiological normal levels with uric acid concentration at 0.5 mmol dm^-3. These well-known interferents have been shown to have no measurable effect on the biosensor's current response. In the range from 0.20 to 0.50 V, the current response increased with increasing potential. In the wide pH range from 2 to 12, current response increased with increasing pH, and the optimum pH was not appearing. We suggested the reason why the optimum pH of the PANI-uricase biosensor does not appear. The relationship between current response and uric acid concentration is good linear in the range from 1.0×10^-3 to 1.0 mmol dm^-3. The Michaelis–Menten constant K_m^' is 7.83 mmol dm^-3 and the maximum current response imax is 58.07μA. The current response of this biosensor increased with increasing temperature and E_a is 40.18 kJ mol^-1 in the B–R buffer. The biosensor was characterized with FTIR, UV-Vis spectra and AC impedance.3. Glucose Biosensor Based on Electroactive Polyaniline at High pHThe use of highly conducting and electroactive polyaniline (PANI) at high pH as substrate to immobilize glucose oxidase is firstly reported in this paper. It is found the biosensor has a larger response current compared with biosensors prepared with control PANI synthesized in proton acid solution. In the range from 0.35 to 0.70 V, the response current increased with the increasing potential. In the wide pH range from 3.0 to 11.0, the response current first increased with the increasing pH, then decreased, and the maximum response current occurred at about pH 8.0. The relationship between response current and the glucose concentration is good linear in the range from 0.005 to 10.0 mmol dm^-3. The Michaelis–Menten constant K_m^' is 31.59 mmol dm^-3 and the maximum response current i_max is 21.28μA. The response current of this biosensor increased with the increasing temperature, and E_a is 32.58 kJ mol^-1 in the B–R buffer. The biosensor was characterized with FTIR, UV-Vis spectra and AC impedance.