Exploring the potential of a urea derivative: an AIE-luminogen and its interaction with human serum albumin in aqueous medium

A urea derivative L1 exhibits Aggregation-Induced Emission (AIE) activity in an acetonitrile–water mixed solvent. The aggregation phenomenon has been corroborated by microscopy and light scattering studies. The ligand (L1) also displays a selective turn-on fluorescence response towards human serum albumin (HSA) in 100% aqueous medium over various other comparable proteins (even bovine serum albumin (BSA)) and enzymes. The weakly emissive probe L1 showed a substantial increase in emission intensity upon binding with HSA through electrostatic interactions. The good linear relationship between the fluorescence enhancement (I/I0 − 1) and the concentration of HSA provided the scope to attain an impressive detection limit as low as 5 μg mL−1. A drug displacement experiment and molecular docking study were employed to ascertain the likely protein (HSA)–ligand binding interactions.