Molecular interactions of bovine serum albumin (BSA) with pyridine derivatives as candidates for non-covalent protein probes: a spectroscopic investigation

Research regarding protein–ligand interactions remains a major concern in the fields of chemistry, biochemistry, pharmacology, and food science. Herein, the interaction of selected pyridine derivatives with bovine serum albumin (BSA) was investigated using UV–Vis and fluorescence spectroscopy. A series of 2-amino-4,6-diphenyl-pyridinium-3-carbonitrile derivatives as fluorescent probes for the determination of BSA revealed that the probes investigated lead to a 12–176-fold increase in emission intensity. The calculated binding parameters support the conclusion that probes bind to BSA in 1:1 stoichiometry with moderate strength, and the quenching for pyridine probes is due to static interaction. The calculated negative value of the free energy change indicates that the complexation is a spontaneous process. Furthermore, from the estimated entropy and enthalpy change values, complexation between the pyridine derivatives and BSA was found to occur primarily via van der Waals interaction and hydrogen bonding. The pH-dependent emission experiment showed that BSA detection with the evaluated probes could be conducted at physiological pH = 7.4 with a wide safety range.