[Interaction between carbaryl and calf thymus DNA enhanced via Cu2+]

The interaction between carbaryl and calf thymus DNA with Cu2+ was studied using fluorescence spectroscopy (FS) and UV spectrum. The quenching process was proved to be single static quenching and the quenching constant decreases with temperature increasing. The experimental results showed that the carbaryl can be intercalated into the twin-screw structure of calf thymus DNA, forming ctDNA-carbaryl adducts. The UV spectrum showed that ctDNA can also result in the increasing color and red shift. In the presence of Cu2+, it was discovered that the apparent association constant (Kalpha) increases and the binding sites number (n) of carbaryl molecules on ctDNA obviously increases. The interaction of the carbaryl and ctDNA was driven mainly by electrostatic force which was enhanced by Cu2+, thus the contribution of deltaH to deltaG increased in the presence of Cu2+ So the interaction between carbaryl and calf thymus DNA was enhanced via Cu+.