Design And Synthesis Of Near-infrared Fluorescent Probes Based On Hemicyanine Dyes And Their Applications In Food Detection

Food safety has been attracting people's attention.Toxic and harmful substances in food can cause people's food poisoning.Therefore,rapid and accurate detection of toxic and harmful substances in food is of great significance.Compared with traditional detection methods,optical probe technology has the characteristics of rapid detection,strong specificity and high sensitivity.It has been widely used in the fields of food toxicant and harmful substances detection,biomedicine and so on.The near-infrared optical probe is a very special kind of fluorescent probe technology.Because of its strong anti-background interference ability,strong tissue permeability and small damage to the living body,it is beneficial to enter the biological body for imaging research.The preparation of optical probes with excellent properties is the basis of detecting various harmful substances in food and disease-causing biomarkers.It has a special position in the development of various fields.Tricarbon cyanine dyes are the most common near-infrared dyes,and their application is limited by their poor light stability.However,the hemicyanine skeleton,as its decomposition product not only retains the near-infrared characteristics of the matrix,but also has a more stable structure,providing more options for the development of various new optical probes.This paper briefly reviews the application of optical probes,especially near-infrared probes in biological imaging.Three types of near-infrared fluorescent probes with different hemicyanine skeletons as fluorescent groups were designed and prepared for the detection of different substances.Based on the detailed study of their properties,the extensive use of them in food detection and biological imaging was studied in depth..The main work includes the following three aspects:1.Hydrogen peroxide is a chlorine-free bleach and sterilizer commonly used in the food processing industry.In this paper,a novel near-infrared fluorescent probe was prepared to detect hydrogen peroxide,using IR-780 hemicyanine skeleton as the fluorescent group and 4-bromomethyl phenyl borate as the specific response group.It shows a fast and sensitive fluorescence response to hydrogen peroxide,and the higher the hydrogen peroxide concentration,the stronger the fluorescence intensity of the reaction system,and the detection limit can reach 0.14 ?M,suitable for food samples.According to cell fluorescence imaging and pixel intensity analysis,the probe has excellent performance,strong cell permeability and high sensitivity,and is suitable for the detection of endogenous hydrogen peroxide in HepG2 cells and mice.2.Tyrosinase is a deterioration factor of fruits and vegetables,it is involved in the Browning reaction of fruits and vegetables.In this paper,a novel near-infrared optical probe with IR-783 hemicyanine skeleton as the fluorescent group and 3-hydroxyphenoxy group as the specific response group was designed to detect tyrosinase.The detection limit of this probe can reach 0.11?g mL-1,which has good sensitivity and can produce a specific response to tyrosinase,avoiding interference from reactive oxygen species.The probe can be used to detect tyrosinase in food samples,melanoma cells,zebrafish and mouse tumor models.3.A novel near-infrared fluorescent probe for detecting carboxylesterase with IR-783 hemicyanine skeleton as the fluorescent group and 4-(chloromethyl)phenyl acetate as the specific response group was prepared.A new type of hemicyanine dye with IR-820 dye as the fluorescent matrix was developed.