Nano-polyaniline Electrochemical Synthesis And Biological Sensing

In the dissertation, nano-polyaniline doped with camphor sulfonic acid (PANI/CSA) has been synthesized by several electrochemical techniques, including chronopotentiometry, potentiostatic method, pulse galvanostatic method, and two-step-method. The influence of the experimental parameters on the PANI morphology and electrochemical performance has been discussed. The polymerization time affects the aspect ratio and the hole size of PANI nanofibers. Lower current density leads to the fibrillar PANI, and higher current density results in scalelike PANI. The aggregate extent of fiber terminal can be controlled by different ratio of pulse time. Compared to one-step method, the electrical conductivity and capacitance of PANI have been enhanced using two-step method. In addition, the PANI morphology changes distinctly in the presence of polyvinylpyrrolidone.The doped ion exchanges of PANI in a series of inorganic and organic acids have been investigated by means of cyclic voltammetry, electrochemical impedance spectrum, scanning electron microscopy, Raman spectra, and so on. The results demonstrate that the PANI morphology possesses transmissibility. Doping and dedoping can be achieved by using potentiostatic method according to the results of UV and fluorescent spectra. The acid groups with larger size can be easily exchanged by those with small size, whereas it's more difficult. This is due to the difference of the anion size.The electrochemical performance of the DNA/PANI/CSA modified electrode has been studied in three different electrolytes. The electric signal of the electrode is distinctly enhanced when the PANI/CSA electrode is fixed with DNA. The PANI/PSSA modified electrode has been prepared and the condition is optimized. The result shows both the conductivity and the strength of signal of DNA/PANI/PSSA are good performance, when the polymerization time of PANI is 900 s.Comparing to the two methods, it is found that the electrode modified with co-doped DNA shows better conductivity. The co-doped DNA/PANI/PSSA electrode was applied to the trace detection of promethazine hydrochloride as an electrochemical biosensor. The dynamic detection range of this sensor to the PZH was from 0.5000 mmol·L^-1 to 0.0313 mmol·L^-1. A detection limit of 0.0012 mmol·L^-1 could be estimated.