Titanium dioxide nanoparticles preferentially bind in subdomains IB, IIA of HSA and minor groove of DNA

Abstract

Titanium dioxide nanoparticles (TiO₂-NPs) interaction with human serum albumin (HSA) and DNA was studied by UV–visible spectroscopy, spectrofluorescence, circular dichroism (CD), and transmission electron microscopy (TEM) to analyze the binding parameters and protein corona formation. TEM revealed protein corona formation on TiO₂-NPs surface due to adsorption of HSA. Intrinsic fluorescence quenching data suggested significant binding of TiO₂-NPs (avg. size 14.0 nm) with HSA. The Stern–Volmer constant (K_sv) was determined to be 7.6 × 10² M⁻¹ (r² = 0.98), whereas the binding constant (K_a) and number of binding sites (n) were assessed to be 5.82 × 10² M⁻¹ and 0.97, respectively. Synchronous fluorescence revealed an apparent decrease in fluorescence intensity with a red shift of 2 nm at Δλ = 15 nm and Δλ = 60 nm. UV–visible analysis also provided the binding constant values for TiO₂-NPs–HSA and TiO₂-NPs-DNA complexes as 2.8 × 10² M⁻¹ and 5.4 × 10³ M⁻¹. The CD data demonstrated loss in α-helicity of HSA and transformation into β-sheet, suggesting structural alterations by TiO₂-NPs. The docking analysis of TiO₂-NPs with HSA revealed its preferential binding with aromatic and non-aromatic amino acids in subdomain IIA and IB hydrophobic cavity of HSA. Also, the TiO₂-NPs docking revealed the selective binding with A-T bases in minor groove of DNA.

Keywords:

• Human serum albumin
• fluorescence quenching
• TiO₂-NPs
• circular dichroism
• docking

Acknowledgment

The authors extend their appreciation to the International Scientific Partnership Program ISPP at King Saud University for funding this research work through ISPP# 0031.