Biophysical studies of single and double alkyl chain metallosurfactants in presence of ionic liquids as additive on its binding to calf thymus DNA

In this work, a binding study of DNA in ionic liquid media of single and double alkyl chain metallosurfactants types (trans-[Co(DH)(2)(HA)Cl](2+) (1) and trans-[Co(DH)(2)(HA)(2)](3+) (2)) where DH = dimethyl glyoxime and HA = hexadecylamine, have been carried out by various spectral techniques. The experimental results indicating that size and shape of the ligand and hydrophobicity of these complexes marked effect on the binding affinity of the complexes to CT DNA in groove binding mode and the order of their intrinsic DNA binding constants k(b) is k(b) = 1.2 x 10(5) (1) < k(b) 3.6 x 10(5) (2). In the presence of an ionic liquid additive, the binding strength of the surfactant-cobalt(III) complex to the DNA increased due to the double alkyl chain of metallosurfactant, being more hydrophobic, exhibits strong binding towards DNA in comparison to the single alkyl chain. This indicates that the long aliphatic chain amine ligand/s present in the metallosurfactant-oxime complex (2) play a definite role in the binding between the metallosurfactant-oxime complex and DNA through their hydrophobicity. Ethidium bromide (EB) shows that these complexes exhibit the ability to displace the DNA-bound EB indicating that the complexes bind to DNA in groove binding site. Observed changes in the circular dichoric spectra of DNA in the presence of metallosurfactant complexes support the strong binding of complexes with DNA. Cyclic voltammetry results also confirm this mode of binding. The results reveal that the extent of DNA binding of (2) was greater than that of (1).

Automated summary

In this study, the binding of DNA with double alkyl chain metallosurfactants in ionic liquid media was investigated using various spectral techniques. The size and shape of the ligand, as well as the hydrophobicity of the complexes, were found to significantly affect the binding affinity of the complexes to DNA. The presence of an ionic liquid additive enhanced the binding strength of the surfactant-cobalt(III) complex to DNA, with the double alkyl chain complex exhibiting stronger binding due to its increased hydrophobicity. The long aliphatic chain amine ligand in the metallosurfactant-oxime complex played a definite role in the binding through its hydrophobicity. The results also showed that the extent of DNA binding was greater for the double alkyl chain complex.