Design, Synthesis, and Evaluation of Near-Infrared Fluorescent Molecules Based on 4H-1-Benzopyran Core

A series of novel fluorescent 4H-1-benzopyrans was designed and developed as near-infrared fluorescent molecules with a compact donor-acceptor-donor architecture. Spectral intensity of the fluorescent molecules M-1, M-2, M-3 varied significantly with the increasing polarities of solvents, where M-3 showed high viscosity sensitivity in glycerol-ethanol system with a 3-fold increase in emission intensity. Increasing concentrations of compound M-3 to 5% BSA in PBS elicited a 4-fold increase in fluorescence intensity, exhibiting a superior environmental sensitivity. Furthermore, the in vitro cellular uptake behavior and CLSM assay of cancer cell lines demonstrated that M-3 could easily enter the cell nucleus and bind to proteins with low toxicity. Therefore, the synthesized near-infrared fluorescent molecules could provide a new direction for the development of optical imaging probes and potential further drugs.

Automated summary

A series of novel near-infrared fluorescent molecules were designed with a compact donor-acceptor-donor architecture, exhibiting significant variations in fluorescence intensity and viscosity sensitivity in different solvent polarities. Among them, one molecule M-3 showed a 3-fold increase in emission intensity in a high viscosity solvent system and a 4-fold increase in fluorescence intensity in the presence of proteins, demonstrating superior environmental sensitivity and potential for optical imaging probe development.