Construction Of Dual Mechanism-Modulated Two-Photon Fluorescence Ratiometric Probe And Its Application In Bioimaging Of Cysteine

Two-photon fluorescence microscopy imaging technology is a new type of fluorescence imaging technology developed by combining two-photon technology and laser confocal microscopy.In bio-imaging,it possesses the advantages of deep tissue penetration,small background fluorescence interference,and high temporal and spatial resolution.Despite the development of two-photon fluorescence imaging probes,conventionally designed two-photon fluorescent molecular probes often only regulate the two-photon fluorophores with a small signal-to-noise ratio through a single signal mechanism,resulting in sensitivity and imaging contrast is difficult to meet the low abundance of biological active substances in biological detection and biological imaging.Therefore,this paper takes the sensitivity of two-photon fluorescent probes as the research entry point,the dual-signal response mechanism is used to coordinate the two-photon fluorophore luminescence performance,a versatile and efficient two-photon fluorescent probe design strategy was applied in the highly sensitive imaging of Cys in living tissues.The specific work is carried out as follows:(1)Intramolecular charge transfer(ICT)and two-photon fluorescence resonance energy transfer(TP-FRET)dual mechanisms synergistically regulate the construction of two-photon ratio-type fluorescent molecules.Through rational design,a structural hybridization compound with a two-photon dye benzo-[h]chromene as a fluorescent energy transfer donor and a benzoxazole with ICT properties as a fluorescent energy transfer acceptor was constructed.Attempts to adjust the wavelength shift of the receptor absorption wavelength by regulating the intensity of ICT,thereby adjusting the level of spectral overlap between two-photon donor emission and receptor absorption,thereby affecting the TP-FRET process and producing a ratiometric two-photon fluorescence signal change(2)Cys is an important small molecule thiol compound in the organism,which plays an indispensable role in the synthesis of proteins,and the level of Cys in the organism is also associated with many diseases.This work uses an ICT-mediated TP-FRET two-photon ratiometric fluorescent probe designed with a benzo-[h]chromene as a two-photon fluorophore and a 4-Cl submitted benzodiazole derivative as an energy acceptor and Cys recognition.A strategy for modulating fluorescent signals using a dual signaling mechanism for high resolution,high sensitivity,and specificity to detect changes in Cys content in imaging organisms.