The Studies Of Biosensors For Conductive Polymer Intercalated Graphite Oxide Nanocomposite

Application foreground of conducting polymer intercalated graphite oxide nanocomposite as conductive material has being paid attention to all through. In this thesis, graphite oxide which has been oxidated at a proper degree, was selected as intercalated main body and polyaniline or polypyrrole as intercalated object body. Exfoliation/adsorption process or in situ polymerization process was applied to composite graphite oxide and polyaniline or polypyrrole. Reduced polyaniline (polypyrrole) intercalated graphite oxide nanocomposite was prepared with hydrazine hydrochloride or KBH4 solution to reduce the nanocomposite. The preparation techniques and the structures and characteristics of the unreduced and reduced nanocomposite have been studied in this paper. The applications of these nanocomposites in the biosensor area have been explored elementarily. The research articles in this thesis are as follows. 1. Reduced polyaniline-intercalated graphite oxide nanocomposite(R-(PAI/GO)) modified electrode was developed to determine ascorbic acid(AA). In Britton -Robinson(B-R) buffer solution (pH 5.02), a couple of redox peaks were obtained of R-(PAI/GO) modified CPE in AA solution with an oxidation peak at -305 mV. The peak current exhibited a good linear range from 1.0×10-9 mol/L to 4.2×10-2 mol/L with a correlation coefficient of 0.9910. Chemicals like dopamine(DA) were verified not interfering with the response of AA. The preparation of the electrode was simple and it had a good reproducibility and stability. The electrode has been used for the determination of AA in pharmaceutical preparations with satisfactory results. 2. Polypyrrole-intercalated graphite oxide nanocomposite(PPy/GO) was prepared by in situ polymerization process using dodecylbenzenesulfonic sodium(DBSNa) to deal with graphite oxide(GO) suspension. The microstructure of PPy/GO was investigated and compared with that of GO using Fourier transform infrared spectrometer(FT-IR), X-ray diffractometer(XRD), transmission electron microscope(TEM) and surface-enhanced raman scattering spectroscopy(SERS). PPy/GO nanocomposite enveloped in carbon paste electrode(CPE) exhibited favorable electrochemical activity, and two peak potentials of cyclic voltammgram (CV) were obtained. Such characteristics of PPy/GO have been employed to investigate the interaction between DNA and PPy/GO. The results indicated that the PPy/GO modified electrode had strong electro-catalytic effect on the redox of single-stranded DNA(ssDNA), and the differential pulse voltammgram(DPV) reductive potential of ssDNA was -652 mV vs.SCE. Also, the modified electrode immobilized with ssDNA could be utilized to monitor the hybridization of DNA and the reductive potential of the hybridization was -480 mV vs.SCE. It covered a linear range from 5.7×10-9 g/ml to 6.8×10-6 g/ml with a correlation of 0.9681 and a good reproducibility and stability. 3. A biosensor for hydrogen peroxide assay based on reduced polypyrrole intercalated graphite oxide nanocomposite(R-(PPy/GO) modified carbon paste electrode which had favourable conductivity was proposed. Fourier transform infrared spectrometer(FT-IR), X-ray diffractometer(XRD) and surface-enhanced raman scattering spectroscopy(SERS) were used to examine the characteristics of R-(PPy/GO). There were some active groups like amidogen, carboxyl and hydroxyl which could attach with glutaraldehyde and covalently combined with HRP. The biosensor provided a linear response to hydrogen peroxide over a concentration range of 3.0×10-7 mol/L ~ 7.0×10-2 mol/L and a detection limit of 1.0×10-7 mol/L. The recovery studies for H2O2 in the real samples gave satisfactory results. 4. The direct detection of clenbuterol(CL) in pig liver without any extraction separation using pyrrole-DNA modified boron-doped diamond(BDD) electrode was reported. The BDD electrode surface were electrochemically modified with pyrrole polymer. After being rinsed carefully with doubly distilled water, the electrodes were immersed in DNA solution to assemble DNA membrane on pyrrole polymer. The pyrrole-DNA modified BDD electrode had strong electrocatalytic effects on the redox reaction of CL. A sensitive cyclic voltammetric response for CL was obtained covering a linear range from 3.4×10-6 mol/L to 5.0×10-4 mol/L with a detection limit of 8.5×10-7 mol/L. The mean recovery of the CL in pig liver sample solution was 102.7 %.