Investigation on damage of BSA molecules under irradiation of low frequency ultrasound in the presence of FeIII-tartrate complexes

The interaction between bovine serum albumin (BSA) and FeIII-tartrate complexes ([FeIII(tar)(H2O)3]− and [FeIII(tar)2]5−) as well as the damage of BSA in the presence of FeIII-tartrate complexes under ultrasonic irradiation was studied by UV-vis and fluorescence spectra. In addition, the influences of ultrasonic irradiation time, FeIII-tartrate complex concentration, ionic strength and solution acidity (pH value) were also examined on the damage of BSA. The results showed that the fluorescence quenching of BSA caused by the FeIII-tartrate complexes belonged to the static quenching. The BSA and FeIII-tartrate complexes interacted with each other mainly through weak interaction and coordinate actions. The corresponding binding association constants (K) and the binding site numbers (n) were calculated. The results were as follows: K1 = 1.67 × 103 L mol−1 and n1 = 0.9699 for [FeIII(tar)(H2O)3]−, K2 = 1.54 × 103 L mol−1 and n2 = 0.8754 for [FeIII(tar)2]5−. Otherwise, under ultrasonic irradiation the BSA molecules were obviously damaged by the FeIII-tartrate complexes. The damage degree rose up with the increase of ultrasonic irradiation time, FeIII-tartrate complex concentration, pH value and ionic strength. And that, [FeIII(tar)(H2O)3]− exhibited higher sonocatalytic activity in a way than [FeIII(tar)2]5−.