DNA binding and antimicrobial studies of some polyethyleneimine-copper(II) complex samples containing 1,10-phenanthroline and L-theronine as co-ligands

The polymer-copper(II) complex samples, [Cu(phen)(L-Thr)(BPEI)]ClO4 center dot 2H(2)O (L-Thr = L-theronine, phen = 1, 10-phenanthroline and BPEI = branched polyethyleneimine), with varying degrees of copper(II) chelate content in the polymer chain, were prepared by ligand substitution method in water-ethanol medium and characterized by Infra-red, UV-Vis, EPR spectral and elemental analysis methods. The binding of these complex samples with calf thymus DNA (CT-DNA) has been investigated by absorption spectroscopy and emission spectroscopy and gel electrophoresis techniques. The experimental results indicate that the polymer-copper(II) complex is an avid DNA binder and the binding constant increased with the increase in amount of copper(II) chelate content in the polymer chain. Besides the electrostatic interaction between a negatively charged DNA molecule and a positively charged polymer-copper(II) complex molecule, other binding modes, such as van der Waals interaction, hydrogen bonding and partial intercalation binding modes may also exist in this system. A sample of polymer-copper(II) complex was tested for its antibacterial and antifungal activity and it was found to have good antibacterial and antifungal activities. (c) 2007 Elsevier Ltd. All rights reserved.