Reactive Near-Infrared Fluorescent Sensors For Small Molecules And Biological Enzymes

Near-Infrared(NIR)fluorescence sensors are helpful for ions,small molecules and enzymes since their long wavelength excition,small biological damages and low background interferences.Reactive fluorescent sensors are widely concerned because of their irreversibility and high recognizition sensitivity.Although some reactive NIR fluorescent sensors existing,less has been reported on imaging hydrazine,hydrogen polysulfides(H2Sn)or human carboxylesterase 2(CES2)and there exists some limitations.Therefore,it is great significance to develop reactive NIR fluorescent sensors for revealing their physiological function.Hydrazine has the serious physiological toxicity.BI-E is a reactive NIR two-photon fluorescent sensor with the absolute quantum yield 0.002,which is obtained by introducing an O-acetyl moiety into DCPO skeleton.Upon reaction with hydrazine,it releases DCPO with the maximum emission at 680 nm,response time 1 min,detection limit 5.7 x 10-8 M,absolute quantum yield 0.011 and two-photon cross-section δmax 30 GM at 830 nm.Over 90%MCF-7 cells viability indicates BI-E has the low toxicity.Confocal imaging indicates that BI-E can recognize hydrazine in living cells by one or two-photon microscopy imaging.H2Sn is a potential signal transduction molecule in cells.Cy-Sn is a reactive NIR fluorescent sensor to H2Sn which is synthesized based on Cy-OH as the fluorphore and p-nitrofluorobenzoate as the recognition unit.It exhibits the response time 5 min and detection limit 2.2 x 10-8 M with a maximum emission at 720 nm for H2Sn.Over 90%RAW 264.7 cells viability indicates Cy-Sn has the low toxicity.Confocal imaging indicates that Cy-Sn can recognize H2Sn and its fluctuation after inflammation and anti-inflammation in cells.Mouse experiments indicate that Cy-Sn has good potential to image H2Sn in living biosystems.CES2 plays an important role in drugs activation and metabolism.Cy-B,Cy-Et and Cy-Tm are reactive NIR fluorescent sensors for CES2 which are obtained by introducing O-benzoyl,O-acetyl and O-trimethylacetyl moiety into Cy-OH skeleton.They exhibit the maximum emission at 715 nm and response time 3 0 min for CES2 with the detection limit 0.11,0.06,0.04 μg/mL,respectively.Among them,Cy-B exhibits the most excellent property to CES2.Over 90%HepG 2 cells viability indicates they have the low toxicity.Confocal imaging indicates that Cy-B exhibits more excellent property than Cy-Et and Cy-Tm,can be used to monitor endogenous CES2 fluctuation during inflammation in living cells.Imaging CES2 in nude mouse liver indicate that Cy-B has good potential to image CES2 in living biosystems.