The coordination sites of phosphorothioate OligoG10 with Cd2+ and CdS nanoparticles

Abstract

The coordination sites of phosphorothioate oligoG₁₀ (PS-oligoG₁₀) with Cd²⁺ and CdS nanoparticles are studied by UV-visible, Raman and XPS spectroscopies. It is found that after coordination with the phosphate group of the DNA, Cd²⁺ ions can destroy the guanine–guanine hydrogen bond of the quadruplex assembly of PS-oligoG₁₀. After addition of sodium sulfide, a TEM image shows that CdS nanoparticles with diameters of about 5 nm was obtained. As a result, the coordination between Cd²⁺ and the PO₂⁻ group of the DNA is cleaved and the coordination site of the DNA with the CdS nanoparticle is found to transfer to the guanine residue of the DNA.