Ratiometric naphthalimide-based fluorescent probes for highly selective detection of carboxylesterase activity

Area of Science:

• Biochemistry
• Enzyme kinetics
• Fluorescent probe development

Background:

• Carboxylesterase (CES) is crucial for drug metabolism, toxicology, and disease diagnosis.
• Existing fluorescent probes often cross-react with homologous enzymes like acetylcholinesterase (AChE) and butyrylcholinesterase (BChE).

Purpose of the Study:

• To design and synthesize novel ratiometric fluorescent probes for selective and sensitive detection of CES activity.
• To overcome the cross-reactivity issues associated with current CES detection methods.

Main Methods:

• Conjugation of a CES-specific carbamate moiety to the naphthalimide fluorophore NIOH via self-immolative linkers.
• Synthesis of two probes: NI-Cl (chlorinated linker) and NI-W (non-chlorinated linker).
• Evaluation of probe performance, including selectivity against AChE and BChE, sensitivity, and detection limits.

Main Results:

• Both NI-Cl and NI-W demonstrated negligible cross-reactivity with AChE and BChE.
• Selective and sensitive ratiometric detection of CES activity was achieved.
• NI-Cl exhibited a low detection limit of 0.038 U/mL, and NI-W showed a detection limit of 0.048 U/mL.
• NI-Cl successfully visualized endogenous CES activity in live cells.

Conclusions:

• The developed probes, NI-Cl and NI-W, are effective tools for the selective and sensitive assessment of CES activity.
• These probes can be utilized in various applications, including drug metabolism studies, toxicology, and disease diagnosis.
• NI-Cl provides a robust method for visualizing endogenous CES activity in live cells, aiding in understanding its physiological and pathological roles.