A non-peptide-based chymotrypsin-targeted long-wavelength emission fluorescent probe with large Stokes shift and its application in bioimaging

As a hydrolase, chymotrypsin (CHT) is involved in many physiological activities, and its abnormal activity is closely related to diabetes, pancreatic fibrosis, chronic pancreatitis and pancreatic cancer. In this work, an innovative long-wavelength emission fluorescent probe TCF-CHT was designed and synthesized for the high specificity detection of CHT, which utilized TCF-OH and a mimetic peptide substrate 4-bromobutyryl as chromogenic group and recognition group, respectively. TCF-CHT exhibited excellent selectivity and eye-catching sensitivity (8.91 ng/mL) towards CHT, “off-on” long-wavelength emission at 670 nm and large Stokes shift (140 nm). Furthermore, the successful fulfillment and perfect performance in imaging endogenous CHT in complex organisms (P815 cells, HepG2 cells, zebrafish and tumor-bearing mice) verified its potential as a powerful tool for the recognition of CHT in complicated biological environments.