Green-emitting carbon dots-protein fluorescence sensing system for specific and sensitive detection of trypsin in urine

Trypsin is a kind of digestive enzyme capable of catalyzing the hydrolysis of proteins. Abnormal changes in the levels of trypsin can cause a series of pancreatic-related diseases. Therefore, based on the special interface interaction between green-emitting ionic liquid-based carbon dots (G-CDs) and BSA, a highly sensitive fluorescence "on-off" mechanism was developed for detecting trypsin in urine. The G-CDs were synthesized by a one-step hydrothermal approach using 2,5-dihydroxybenzoic acid (2,5-DHBA) and 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIM]PF 4 ). The interaction between G-CDs and bovine serum albumin (BSA) led to the formation of the G-CDs-BSA fluorescence sensing system, which induced aggregation and fluorescence enhancement of G-CDs. The G-CDs-BSA system was disrupted under optimal incubation conditions after the addition of trypsin, and the fluorescence was quenched. According to the fluorescence quenching value (∆F) of the system, the quantitative analysis of trypsin in urine was realized and demonstrated good recoveries. This study not only developed a novel fluorescence sensing system with excellent performance for trypsin detection, but also provided a theoretical basis for the binding of carbon dot-protein systems.