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

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 (Ksv) was determined to be 7.6 × 102 M−1 (r2 = 0.98), whereas the binding constant (Ka) 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.