A new optical method to analyze ligand-protein interaction: affinity-based screening system

Abstract This study introduced a simple and effective method for real-time detection of ligand-protein interaction. In the present study, bovine serum albumin (BSA) as a model protein was immobilized on the surface of inverse opal nanostructures (SiO2) by covalent bonding. The interaction of common glitazones; pioglitazone (PIO), rosiglitazone (ROS) and troglitazone (TRO)) was optically monitored in real-time at the stop band gap of 510±0.4 to detect possible shifts due to the changes of the local refractive index. The preliminary data, from the experimental investigation, indicated that the present screening system is able to detect effectively the binding affinity of drug molecules to a target in real-time, although the obtain results were compared with the other routine methods, surface plasmon resonance (SPR) and virtual screening. The results indicated that the stop band peak at 510±0.4 was significantly red-shifted by binding of glitazone molecules, particularly PIO. The constant of binding affinity for PIO-BSA complex was estimated to be 5.5×10−8M−1, which was less than the other complexes, showing its higher tendency to bind to the immobilized BSA than the other glitazones. These results were also approved by SPR and virtual screening studies.