a study on the aggregation and calf thymus dna binding characteristics of anionic cobalt(ii) tetrasulfonated phthalocyanine

the aggregation behavior of anionic cobalt(ii) 4,4′,4ʺ,4‴-tetrasulfonated phthalocyanine, [co(tspc)4-] was studied at its various concentrations and different ionic strengths using optical absorption and resonance light scattering (rls) spectroscopies in 5 mm phosphate buffer, ph 7.0 at 25 °c. the results show no aggregation behavior at concentration range of 5.1 × 10-6-7.5 × 10-5 m. also, the interaction of [co(tspc)4-] with calf thymus dna (ct-dna) was studied by uv-vis absorption, fluorescence spectroscopies and thermal denaturation measurement. the binding constants were obtained at various ct-dna concentrations using squad software. the thermodynamic parameters were calculated by the van't hoff equation. the results show that the process is entropy-driven. the fluorescence study represents the quenching effect of [co(tspc)4-] on bound ethidium bromide (etbr) to ct-dna.