Antibacterial Activity of Carboxymethyl Chitosan-Cu (Ⅱ) Complex and Interaction with DNA

The antibacterial activity of carboxymethyl chitosan-Cu(Ⅱ) complex (CMC-Cu) was studied in vitro. The interaction between CMC-Cu and herring sperm DNA was investigated by cyclic voltammetry and spectroscopy. Results showed that CMC-Cu had good antibacterial activity against B.subtilis, St.aureus, E.coli and P.aeruginosa. An oxidation peak of CMC-Cu appeared at 0.442 V, the electrochemical reaction of the Cu2+ on the glass carbon electrode was controlled by the process of diffusion. Adding DNA into the CMC-Cu solution, the oxidation peak current decreased and the peak potential shifted to negitive. More over, the absorption intensity of DNA was strengthened and blue shifted with the increasing of CMC-Cu concentration. The fluorescence intensity of DNA-NR system was increased by CMC-Cu. The interaction mode between CMC-Cu and herring sperm DNA was electrostatic.