B, S, N co-doped carbon dots-based highly sensitive and rapid nanoprobe for monitoring of pepsin activity in human saliva and its cell imaging

Gastroesophageal reflux disease (GERD) is widespread, but screening is difficult due to its non-specific symptoms. Detecting pepsin in saliva is a non-invasive and specific diagnostic method, yet it requires enhancements in reaction time, selectivity, and sensitivity. In this study, a highly sensitive detection method has been developed for monitoring pepsin activity in human saliva based on boron, sulfur, and nitrogen co-doped carbon dots (BSN-CDs) for the first time. The manufactured BSN-CDs exhibit exceptional photoluminescent properties, high water solubility, and stability in varying salt concentrations and pH levels. The nanoprobe shows a fast response time and a wide detection range from 0 to 60 µg/mL for pepsin with a detection limit of 0.24 µg/mL, making it a valuable tool for clinical diagnostics. To our knowledge, this is the most responsive material for pepsin activity reported to date. The method’s viability was confirmed by accurately measuring pepsin in human saliva samples, achieving recovery rates between 96.0 % to 108.5 %. Moreover, the study investigates using these carbon dots for imaging HepG2 and SiHa cells, highlighting their broader biomedical potential. It concludes that BSN-CDs are promising nanomaterials for sensitive biomolecule detection and advanced imaging techniques.