Graphene Oxide-Modified DNA Electrochemical Sensors For Monitoring The Degradation Of Organic Pollutants

In this thesis, graphene oxide modified DNA biosensors were prepared withdifferent methods, which were used to monitor the degradation of several organicpollutants. The main contents were described as follows:We compared the effect of DNA molecules immobilized on the bare glassy carbonelectrodes （GCE）, carbon nanotubes modified elctrodes （CNTs/GCE） and graphene oxidemodified electrodes （GO/GCE） under same adsorption conditions. GO-modifiedelectrodes dramatically improved the peak current of purines, and with the lowbackground current. DNA/GO/GCE biosensors were prepared in pH4.4acetate buffersolution in the presence of0.50mg·mL^-1DNA, with0.1V adsorption potential and200sadsorption time. The DNA/GO/GCE biosensors were used to study the interactionbetween catechol and DNA. There was a linear relation between the ratio of adeninepeak current （R%） and the concentration of catechol from1.00×106mol·L1to1.00×104mol·L1. The linear equation can be described as R%=4.43+0.15c (μmol·L^-1). Thebiosensors were used to monitor the voltammetric behavior of catechol after treated withthe UV/H₂O₂process. The result was close to that determined by the UV-Visspectrophotometer.The interaction between diclofenac sodium （DFNa） and dsDNA was investigated byelectrochemical methods. Intercalation and electrostatic interaction existed between themin pH3.0citric acid buffer solution, while only intercalation existed in pH7.0phosphoric acid buffer solution. The electrochemical parameters of DFNa in presence orabsence of dsDNA had no evident change and the binding ratio was calculated to be1:1.GO-dsDNA/GCE biosensors were used to detect DFNa. The peak current of guanine waslinearly decreased with increasing concentration of DFNa from1.00×10^-6to1.30×10^-4mol·L^-1and the linear regression was expressed as i （μA）=16.38–0.037c (μmol·L^-1).We investigated the interaction between benzotriazole （BTA） and DNA by GO/GCE. With increasing concentration of BTA, the peak current of DNA decreased and thepotential shifted positively, which indicated that BTA intercalated the double helixstructure of DNA. Based on hydrogen bonding between them, we detected theconcentration of BTA. The range of linearity was20.00-1000.00μmol·L^-1.