Excellent benzocoumarin-based ratiometric two-photon fluorescent probe for H₂O₂ detection

Area of Science:

• Chemical Biology
• Biomedical Imaging
• Fluorescent Probe Development

Background:

• Hydrogen peroxide (H2O2) is crucial for biological regulation.
• Two-photon (TP) fluorescent probes offer advantages for deep tissue imaging over one-photon (OP) probes.
• Existing TP probes often lack high fluorescence efficiency and distinct spectral properties for H2O2 detection.

Purpose of the Study:

• To design and evaluate novel benzocoumarin-based ratiometric TP fluorescent probes for H2O2 detection.
• To understand the structure-property relationships governing TP fluorescent performance.
• To develop probes with enhanced imaging capabilities, including simultaneous NIR and TP imaging.

Main Methods:

• Synthesis of benzocoumarin-based TP fluorescent probes and their corresponding product molecules.
• Theoretical evaluation using time-dependent density functional theory (TD-DFT) and quadratic response theory.
• Experimental determination of spectral properties and fluorescence efficiencies.
• Investigation of the effect of structural modifications on photophysical properties.

Main Results:

• Designed and characterized a series of benzocoumarin-based TP probes for H2O2.
• Identified probe BC-3 and product DCCA-3 with large two-photon absorption (TPA) cross-sections in the NIR region and significant Stokes/emission shifts.
• Achieved simultaneous NIR and TP imaging of H2O2, a novel capability.
• Elucidated the fluorescence quenching mechanism in benzo[f]coumarin derivatives.

Conclusions:

• Developed high-performance benzocoumarin-based TP fluorescent probes for H2O2 detection.
• Probe BC-3 enables unprecedented simultaneous NIR and TP imaging of H2O2.
• Structure-property relationship studies provide insights for designing advanced TP probes.