Design and synthesis of the BODIPY–BSA complex for biological applications

A quinoxaline-functionalized styryl–BODIPY derivative (S1) was synthesized by microwave-assisted Knoevenagel condensation. It exhibited fluorescence enhancement upon micro-encapsulation into the hydrophobic cavity of bovine serum albumin (BSA). The S1–BSA complex was characterized systematically using ultraviolet (UV)–visible absorption, fluorescence emission, kinetics, circular dichroism and time-resolved lifetime measurements. The binding nature of BSA towards S1 was strong, and was found to be stable over a period of days. The studies showed that the S1–BSA complex could be used as a new biomaterial for fluorescence-based high-throughput assay for kinase enzymes.