Multispectroscopic and computational study of interaction of the bovine serum albumin with atropine and atropine-loaded chitosan nanoparticles (synthesized and characterized)

Abstract

Two different systems of bovine serum albumin (BSA) were used for multiple spectroscopic and computational studies to determine interaction of BSA and atropine (Atrop), that is, BSA-Atrop system and Atrop-loaded chitosan nanoparticles (Atrop@CS NPs), that is, BSA-Atrop@CS NPs system. The study suggests that BSA-Atrop system and BSA-Atrop@CS NPs system involve non-fluorescent complexes of K sv = 3.2 × 103 Lmol−1 and 3.1 × 104 Lmol−1, kq = 3.2 × 1011 Lmol−1 s−1 and 3.1 × 1012 Lmol−1 s−1, the binding constant K b = 1.4 × 103 Lmol−1, 2.0 × 102 Lmol−1, respectively, and number of binding sites n ∼ 1 for both the systems. The negligible conformational changes induced in BSA were also observed. Synchronous fluorescence spectroscopic study revealed that more quenching occurred in intrinsic fluorescence of tryptophan (Trp, W) than that in tyrosine residue (Tyr, Y). UV–vis spectroscopic study verified the presence of static quenching from the presence of BSA-Atrop and BSA-Atrop@CS NPs complexes. CD spectra confirmed the conformational changes induced in BSA upon increment of concentrations of Atrop and Atrop@CS NPs separately into the constant concentration of BSA. The coherent observations from various spectroscopic studies were in agreement with those of computational study, showing BSA-Atrop complex formation and other related details. The hydrogen bonds (H-bonds), van der Walls (vdW) interactions and -type of interactions were mainly involved in stabilization of the formed BSA-Atrop complex. Communicated by Ramaswamy H. Sarma