Investigating the interaction between DNA-templated gold nanoclusters and HSA by spectroscopy

Gold nanoclusters (AuNCs) have attracted great attention in bioimaging and drug transportation due to their biocompatibility, but few involved their potential toxicity studies. In this paper, to evaluation of the toxicity of DNA-AuNCs at the molecule level, the interaction between DNA-AuNCs and HSA was studied in detail by various spectral methods. DNA-AuNCs could quench the intrinsic fluorescence of HSA by static quenching. Various thermodynamic parameters were evaluated using the van't Hoff equation. The results indicated that the interaction of DNA-AuNCs with HSA was spontaneous (ΔG<0) and was driven by favorable negative standard enthalpy changes (ΔH<0) and unfavorable negative standard entropy changes (ΔS<0). Therefore, the main forces in this process were van der Waals forces and hydrogen bonds. Furthermore, the competitive binding experiments indicated that DNA-AuNCs bind primarily to site I of HSA. By analyzing the circular dichroism spectroscopy, synchronous fluorescence and FT-IR spectra, the HSA conformation changed slightly in the presence of DNA-AuNCs, indicating that the potential toxicity of DNA-AuNCs lead to structural damage of HSA. This work clarified the binding mechanism of DNA-AuNCs to HSA and provided important information for the potential toxicity risks of DNA-AuNCs to human health.