Electrochemical Studies On The Interaction Of Small Molecular Complexes With DNA And Chitosan

DNA is a kind of key biologic large molecule, and it plays an important role in life genetic code' interpretation, transcription and copy. The research about the interaction of DNA with distinguishing molecules is the pop field of life science. The combination of electrochemistry and spectral studies is important to understand the mechanism of the interaction of DNA with small molecular complexes. Chitosan(CTS) is one of the natural polymers, and its special structure make it demonstrate unique exchange, chelation and adsorption abilities towards many metal cations, organic substances and so on, which allow it to be widely used in chemistry. The reports about the determination of CTS are few, and mostly focus on spectrophotometry. However, a report about using the directly electrochemical determination has not been seen. In this thesis, the mechanism of some kinds of small molecular complexes with DNA was studied by electrochemistry, UV-vis spectrophotometry and fluorescence spectrophotometry, and the methods were applied to the analysis. And besides, we carried out the study of the electrochemical behaviors of chitosan(CTS), which was used to determine the CTS in samples.The main contents are listed as follows:(1) We studied the interaction of the CTZAMB-Cu(II) complex with DNA by the electrochemistry and UV-vis spectral methods, and suggested that CTZAMB-Cu(II) could interact with phosphate groups outside of DNA by electrostatic interaction. The formation of the CTZAMB-Cu(II)-DNA complex results in the decrease in peak current, and the decrease of peak current is linear with DNA concentration in the range from 3.0 × 10-7 to 7.0 × 10-6 g/mL, and the detection limit is 1.0 × 10-7 g/mL.(2) We studied the interaction of BZ with DNA by the electrochemistry and UV-vis spectra and fluorescence spectra methods, and suggested that BZ could interact with DNA by partial intercalation mode. The formation of the BZ-DNA complex results in the decrease in peak current, and the decrease of peak current is linear with DNA concentration in the range from 7.0 × 10-8 to 6.0 × 10-6 g/mL, and the detection limit is 3.0 × 10-8 g/mL.(3) We studied the electrochemical behaviors of chitosan (CTS) in a 0.05 mol/L potassium hydrogen-phthalate buffer solution (pH 2.5). The characteristics and themechanism of the electrode reaction were also investigated, and this method was applied to determine the content of CTS in the samples. The peak current is linear with the concentration of CTS from 5.0 x lO"7 to 1.5 x 10~5 g/mL, and the detection limit is 1.0 x 10"7g/mL.