Molecular engineering of a fluorescent probe for highly efficient detection of human serum albumin in biological fluid

Human serum albumin (HSA) is synthesized by the liver, accounting for 60 % of total plasma protein in vertebrates' blood. It is the most predominant extracellular plasma protein that acts as a repository and transporter of exogenous and endogenous substances in the blood of healthy humans. Decreased albumin concentration in the human body or its abnormal levels indicate the occurrence of hepatic, renal, and digestive-related diseases. Therefore, accurate quantification of HSA is of great significance in diagnostic testing and routine clinical analysis of albumin-linked diseases. Herein, a class of triphenylamine rhodanine-3-acetic acid (mRA)-a bifunctional fluorescent molecule with twisted intramolecular charge transfer (TICT)-induced emission characteristics is synthesized and employed as a novel sensing probe for the fluorescent detection of human albumin. mRA can be selectively lighted up through site-specific interactions with serum albumin-binding moieties and show enhanced photophysical or biological response efficacy. Understanding the interaction of mRA with HSA at the molecular level was carried out using docking methodology to explore the site-specific interaction phenomenon. The resulting fluorescence strategy produced a dose-dependent signal response enhancement upon interaction with HSA in the concentration range of 0.01–400 μg/ml. The sensor probe exhibits a low detection limit of 10 ng/mL and is found to be a feasible, low-cost, and effective approach for HSA analysis in complex biological fluids for early detection and diagnosis of albumin-related diseases.