Design Synthesis And Application In Fluorescence Bioimaging Of Silicon-based Rhodamine Fluorescent Probe

In recent years,fluorescence imaging technology has played an important role in many fields due to its excellent imaging ability to target groups and biological structures.Due to near-infrared light excitation,two-photon fluorescence imaging technology reduces the biological damage,and deepens the penetration of biological tissue.Therefore,biological tissue imaging can be completed.Fluorescent probes are the core of fluorescence imaging technology.Combining two-photon imaging technology with fluorescence monitoring technology,it is particularly important to design and synthesize fluorescent probes with excellent two-photon performance.At present,due to the limitations of two-photon absorption cross-section and water solubility,fluorescent probes that can be used for two-photon fluorescence imaging are still scarce.Therefore,a series of fluorescent probes were synthesized by introducing methyl,trifluoromethyl,methoxy and two methoxy groups on the 9-position benzene of silicon-rhodamine,and their physical and two-photon bioluminescent imaging properties were investigated.In the PBS solution,the four fluorescent probes have good solubility.With the introduction of methoxyl,the fluorescence quantum yields and the photostability of SiR-O and SiR-DO were enhanced.With the introduction of bismethoxy,the chemical stability of SiR-O was improved.Cytotoxicity experiments showed the survival rate of Hela cells was up to 85% after 24 h incubation with two probes,indicating that biocompatibility was improved.Probes can enter the cell within 1 min,indicating that their cell membrane permeability were enhanced.The localization coefficients were up to 88% with mitochondrial green,indicating that they have mitochondrial localization capacity.The photon absorption cross-section experiments show that with the introduction of methoxy,two-photon absorption cross of probes SiR-O and SiR-DO were improved.Two fluorescence probes can enter the tumor cells and nerve cells,indicating that cell membrane permeability was enhanced.The localization coefficients of SiR-O and SiR-DO with mitochondrial green were up to 90%,indicating that they have excellent mitochondrial localization function in neurons.The fluorescence intensity of SiR-O and SiR-DO remains unchanged after two-photon laser irradiated 10 min in nerve cells,indicating that fluorescence stabilities were improved.The permeation thickness of two probes in mouse brain tissue were 70 μm and 100 μm,indicating that their tissue imaging performance were enhanced.Experiments show that two probes can be used as two-photon fluorescence imaging tools in the field of biological imaging.