Investigating the biophysical interaction of serum albumins-gold nanorods using hybrid spectroscopic and computational approaches with the intent of enhancing cytotoxicity efficiency of targeted drug delivery

Abstract

In this contribution, biophysical aspects of binding interaction, conformational changes, and molecular simulation studies of human and bovine serum albumins (HSA and BSA) exposed to gold nanorods (AuNRs) are thoroughly investigated and their bio-nanoconjugates were then used in in-vitro cytotoxic studies. The structural variations of AuNRs in the presence of serum proteins were confirmed by absorbance and high-resolution transmission electron microscopic (HR-TEM) pictures. According to the results of the steady-state emission quenching, AuNRs affect the intrinsic emission of HSA and BSA by a static mechanism. Synchronous emission spectrum results showed that the microenvironment near the tryptophan and tyrosine amino acid residues of serum proteins is altered, and the impact is stronger toward tryptophan than tyrosine. Furthermore, it was demonstrated by infrared, absorbance, and three-dimensional (3D) luminescence spectroscopic methods that the binding of AuNRs can arouse concerns and cause changes in the structural and/or microenvironmental characteristics of HSA and BSA. An outcome of the computational molecular simulation study supports the stability of the bio-nanoconjugate, and molecular docking interaction investigations suggest that the two-dimensional AuNRs surface associated with the cysteine residue of HSA and BSA contains sulphur atoms. Furthermore, using an in vitro model using the A-549 and MCF-7 cell lines, we calculated the toxicity and the effectiveness of cellular absorption of the AuNRs and their bio-nanoconjugates as a function of supplied dosage. These cytotoxicity findings demonstrate that protein adsorption affects AuNRs' physicochemical characteristics as well as enhances their subsequent biological function.