An ester-functionalized cationic gemini surfactant mediated structural transitions of porcine serum albumin (PSA) via binding interaction

Abstract

Keeping in mind the contemporary environmental concern raised over the disposal of surfactants into water bodies, we synthesized biodegradable cationic gemini surfactant ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride (16-E2-16), which bears easily cleavable ester functionalities (betaine type arrangement) in its spacer. This research article encompasses an in vitro analysis of the interaction between the synthesized gemini surfactant and a serum transport protein, porcine serum albumin (PSA) under physiological mimetic conditions. A multi-technique approach was exploited to explore the structural alterations induced in PSA at different concentrations of 16-E2-16. Fluorescence measurements unraveled a substantial interaction between PSA and 16-E2-16 (Kb∼104M−1). Synchronous and three-dimensional fluorescence spectra further validated the binding of 16-E2-16 with PSA. Pyrene emission fluorescence depicted an increased hydrophilicity experienced by the probe molecules on account of their expulsion into the solvent due to a comparatively stronger binding of the gemini surfactant with PSA. The UV–vis studies established the ground state complexation of the gemini with PSA. Interestingly, far-UV CD results demonstrated the stabilization of secondary structure of PSA at concentrations below and above the CMC of 16-E2-16. Near-UV CD spectra revealed negligible changes in the tertiary structure of PSA. Additonally, CV scans depicted electrochemically inactive 16-E2-16−PSA complex formation and thus reinforced the findings of spectroscopic investigations. Overall, it is inferred that 16-E2-16 binds efficiently with PSA affecting both its microenvironment and conformation. Owing to these favorable interactions, 16-E2-16 may find its application as a prospective excipient in drug, skincare and immunoassay reagent formulations, in which serum albumins are frequently used.