Experimental and biophysical interaction studies of alanine modified polyaniline with bovine serum albumin and human serum albumin: Influence of alanine modification on the spectral, morphological and electronic properties

The present work reports for the first time, modification of aniline with alanine (Ala) in mole ratios of 80–20, 50–50 and 20–80 via ultrasound-assisted polymerization. The formation of Ala-incorporated polyaniline (PANI) was confirmed via FTIR, UV–visible and SEM studies. The geometry optimization, Mulliken charge distribution, vibrational as well as electronic spectral analysis was carried out using Gaussian 09 software with B3LYP/6311 G(d) basis set. Quenching of bovine serum albumin (BSA) and human serum albumin (HSA) by Ala/PANI followed the static mechanism which was confirmed by the fluorescence studies and Stern Volmer plots. The binding constant (Kb) values were found to be higher for Ala-PANI oligomers (∼105 LM−1) containing higher loading of PANI. The binding affinity of Ala/PANI towards BSA as well as HSA was found to be fairly good and the docking studies established that hydrogen bonding as well as Van der Waal’s forces played a significant role in the binding process.