Investigation on the binding interaction of rhodamine B with human serum albumin: effect of metal ions

Abstract

The binding of rhodamine B (RB) to human serum albumin (HSA) in the absence and presence of Cu²⁺ or Fe³⁺ under simulated physiological conditions was studied by using various biophysical methods for the first time. The results showed that the interaction between HSA and RB could spontaneously result in the formation of HSA-RB complex (namely, static quenching mechanism) through hydrophobic interactions and hydrogen bonds irrespective of the absence or presence of metal ions. The presence of metal ions led to the reduction of binding affinity of RB to HSA compared with no metal ions, which might result from the conformational change of HSA caused by the binding of metal ions. Furthermore, the analysis of UV-vis absorption, circular dichroism, synchronous fluorescence and three-dimensional fluorescence experiments demonstrated that the addition of RB induced conformational and microenvironmental changes of HSA without and with metal ions. In short, this work will be helpful to in-depth understand the transport mechanism and biological effect of RB and the effect of metal ions on the interaction of HSA-RB in vivo.

Keywords:

• Rhodamine B
• human serum albumin
• metal ions
• interaction
• spectroscopy

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (21506152), the Natural Science Foundation of Tianjin (19JCYBJC21000), the Natural Science Foundation of Shaanxi Province (2015NY-041 and 2020NY-131), and the Food Science and Engineering Key Disciplines of Shaanxi Xueqian Normal University.