Based On The Design And Synthesis Of IR-780 Near-infrared Fluorescent Probe And Its Application In Food Safety Detection

Food safety problems,emerging in endlessly in recent years,have caused the occurrence of foodborne diseases which are serious threat to human health.So it is very important for food safety detection.Spectroscopic analytical methods are widely used because of their simplicity,great temporal and spatial sampling capacity.In particular,fluorescent probes with a near-infrared(NIR)analytical wavelength are rather desirable for practical applications because of their good tissue penetration and low autofluorescence and biological damage.Excellent spectroscopic probes are the bases for the development of novel spectroscopic analytical methods.Hemicyanine skeleton,a fluorophorewith excellent properties,which can be generated via the decomposition of its unstable precursor of IR-780 but still possesses an NIR feature,has attracted widespread attention.Fluorescence probe and detection technology play a decisive role in the development of life sciences.In this study,several novel NIR spectroscopic probes are designed and synthesized for food safety analysis.The major results achieved are described as follows:1.A near-infrared fluorescence probe is developed and applied to fluorescence imaging of sulfur dioxide derivatives in living HeLa cells and mice.The probe is a readily prepared and stable hemicyanine skeleton,which exhibits superior analytical performance such as near-infrared fluorescence emission over 700 nm and high sensitivity with a low detection limit of 0.37 ?M.The proposed detection mechanism upon reaction with sulfur dioxide derivatives is based on 1,4-nucleophilic addition reaction in the ethylene group,followed by an electron transfer and weakening of the electron-withdrawing character.As a result,the reaction produces a distinct color and fluorescence change.More importantly,the probe is cell membrane permeable,and its applicability has been successfully demonstrated for monitoring sulfur dioxide derivatives in living HeLa cells and male BALB/cmice.This method is simple,and may be useful for the imaging of sulfur dioxide derivatives in biology.2.A new near-infrared fluorescence off-on probe is developed and applied to fluorescence imaging of carboxylesterase in living HepG-2 cells and zebrafish pretreated with pesticides(carbamate,organophosphorus and pyrethroid).The probe is readily prepared by connecting 4-acetoxybenzyloxy as a quenching and recognizing moiety to a stable hemicyanine skeleton that can be formed via the decomposition of IR-780.The fluorescence off-on response of the probe to carboxylesterase is based on the enzyme-catalyzed spontaneous hydrolysis of the carboxylic ester bond,followed by a further fragmentation of the phenylmethyl unit and thereby the fluorophore release.The detection limit is 4.5×10-3 U/mL.More importantly,the probe is cell membrane permeable,and its applicability has been successfully demonstrated for monitoring carboxylesterase activity in living HepG-2 cells and zebrafish pretreated with pesticides,revealing that pesticides can effectively inhibit the activity of carboxylesterase.The superior properties of the probe make it of great potential use in indicating pesticide exposure.3.A novel "Turn-on" near-infrared fluorescence probe is developed and applied to benzoyl peroxide(BPO)detection.By connecting 4-(Bromomethyl)benzeneboronic acid pinacol ester as the recognition unit to a stable hemicyanine skeleton,the probe is readily prepared,which exhibits superior highly specific and rapid fluorescence response toward benzoyl peroxide.The detection limit was estimated to be 36 nM.The probe was employed for determining BPO in food samples with good sensitivity.