Self-assembled nanosensor based on squaraine dye for specific recognition and detection of human serum albumin

Abstract

“Aggregation-caused signal change”, a well-established mechanism, should not be ignored for sensing, while small molecule based on self-assembly and disaggregation has been studied and used for protein detection. In this work, we have synthesized a novel fluorescent chemosensor SQ with a polyether chain to enhance water solubility, and this has been used for the detection of human serum albumin (HSA) in aqueous solution with excellent sensitivity and selectivity. SQ was aggregated into nanoparticles with an average particle size of 458nm in neutral solution and showed fluorescence silent due to the aggregation-induced quenching. However, addition of HSA decreased the average particle size of SQ to 295nm and released the fluorescence because of the reassembly of the SQ-HSA complex. More importantly, HSA could be selectively detected in the presence of other biological proteins and the main physiological inorganic anions and cations with the detection limit estimated as 15.6nM according to 3σ/k. This versatile strategy suggests that squaraine dyes can be used as fluorescence-enhanced probes for the quantitative detection of HSA as well as in applications for the detection of HSA in urine samples.