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

Abstract

Gold nanoclusters (AuNCs) have attracted great attention in bioimaging and drug transportation due to their biocompatibility, but a few studies have shown their potential toxicity. In this paper, for the evaluation of the toxicity of DNA-AuNCs at the molecule level, the interaction between DNA-AuNCs and HSA was studied in detail using 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. These 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 led to structural damage in HSA. This work clarifies the mechanism of binding of DNA-AuNCs to HSA and provides important information for the potential toxicity risks of DNA-AuNCs to human health.