Design, Synthesis And Bioimaging Of HNO Fluorescent Probes

Nitrosyl hydrogen(HNO)is a one-electron reduction and protonation form of nitric oxide(NO).In recent years,with the continuous understanding of HNO,more and more research results show that HNO has unique biological activity and pharmacological applications.For example,HNO has the potential to treat heart failure and has anti-inflammatory effects.It can also inhibit the activity of aldehyde dehydrogenase,treat alcoholism,and alleviate ischemia-reperfusion injury.Therefore,it is important to develop an efficient method for detecting HNO in an organism.Conventional analytical methods for detecting HNO are not suitable for detecting HNO in living systems due to the disadvantages of complex pretreatment and invasive damage to biological samples.Fluorescent probes are widely used for biomolecule detection because of their fast response,high selectivity,and good biocompatibility.At present,there are many types and quantities of HNO fluorescent probes reported,most of which can selectively detect and sensitively detect HNO,but there are still some shortcomings,such as excitation light is short-wavelength ultraviolet light or visible light,and is susceptible to biological systems.The effects of autofluorescence and photobleaching,and the depth of tissue penetration of their imaging is usually low,and their application in organisms is limited.Based on this,it is necessary to select the fluorophore with good performance of two-photon excitation and the design of fluorophore HNO probe in near-infrared.The paper based on the Staudinger reaction of HNO and triarylphosphine(Staudinger):The first part,the design,synthesis and application of two-photon HNO fluorescent probe.Based on the intramolecular charge transfer mechanism,a novel two-photon HNO fluorescent probe was designed and synthesized by selecting 2,6 naphthalene derivatives with "push-pull" electronic structure.The probe uses diphenylphosphinobenzoate as the recognition group for HNO and is also a fluorescence quenching group.The selectivity of the probe is high and the fluorescence enhancement is about 140 times.The coating of the probewith nanomicelles effectively improves the water solubility of the probe.The probe is used in a living cell with a two-photon microscope at an excitation wavelength of 750 nm.Fluorescence imaging studies of endogenous and exogenous HNO;the probe has a tissue penetration depth of up to 280 ?m.The second part is the design,synthesis and application of two-photon HNO fluorescent probes targeting lysosomes.An open-type two-photon HNO fluorescent probe was constructed by using a naphthalimide as a fluorophore and a morpholine ring which can be localized to a lysosome.The detection limit of the probe was as low as 202 nM;the fluorescence intensity was almost saturated at 2 min;and the fluorescence imaging of endogenous and exogenous HNO in the cells was performed on the probe with a two-photon microscope at 780 nm.A lysosomal fluorescence colocalization imaging study was performed.The third part is the design,synthesis and application of near-infrared HNO fluorescent probes.A novel near-infrared fluorescent probe NIR-HNO with a recognition group of diphenylphosphine benzoate was synthesized based on isophorone.With an excitation wavelength of 556 nm,the maximum emission wavelength is 688 nm.The nano-micelle-encapsulated probe effectively improved the water solubility of the probe,and the probe was subjected to fluorescence imaging of exogenous HNO in living cells and living zebrafish.