Highly Sensitive Molecular Probes Have Been Developed For Imaging Studies Of Three Living Substances

Carboxylesterase is an important active enzyme in human body,playing a key role in the detoxification or metabolic activation of various ester-drugs,environmental toxicants,and carcinogens.But the acid metabolites produced by hydrolysis may affect the normal function of organelles.Zinc ion is an important signaling molecule in vivo,playing a significant role in various physiological processes of biosystem.However,researchers have found that abnormal zinc ion concentration can cause neurological disorder and is closely related to malignant tumors.Therefore,it is of great significance to develop the physiological and pathological processes response to esterases,pH and zinc ions for human to conquer cancer and other major diseases.Compared with traditional detection technology,molecular-probe-based fluorescence imaging techniques are more favored by researchers because of their low damage,high resolution,visualization and other functions.However,due to the limitation of sensitivity,the sensitivity is low and the selectivity is unsatisfactory.In addition,because of lacking the design strategies of linkage locus response,electronic conjugate regulation,spatial structure torsion,and innovatively integrating reaction mechanism or electronic regulating mechanism,which limits the development of linkage response and real-time in-situ monitoring technology for the treatment of objects by probe.Moreover,in imaging analysis,the fluorescence probe is also limited by wavelength,dose,reporting intensity and background,so it is often unable to obtain high fidelity fluorescence imaging results.In recent years,researchers have developed multiple fluorescent probes for detecting carboxylesterase and zinc ions,but there is still a lack of probe for successively resporting carboxylesterase and pH.As for the imaging study of zinc ion probe is still limited to cell tissue and aquatic animals instead of in vivo levels.The detailed works are as follows:1.Ratiometric two-photon fluorescent probe for in situ imaging of carboxylesterase-mediated mitochondrial acidification during medication.We have designed and synthesized a two-photon ratio fluorescent molecular probe(E)-4-(2-(7-acetoxy-2-oxo-2H-chromen-3-yl)vinyl)-1-(4-(chloromethyl)benzyl)pyridin-1-ium chloride(CEMT).The probe takes carboxylic acid ester as the trigger site of enzymatic hydrolysis.The resulting product has the phenolic hydroxyl group that can respond to pH.For the first time,we achieved the detection of the successive response of carboxylesterase and pH.The probe has several advantages: high sensitivity,relatively large two-photon absorption cross-sectional area(?=165 GM),dual ratiometric,strong mitochondrial targeting(Pearson correlation coefficient is 0.91 and 0.89 when pH is 7.4 and 4.98 respectively),and rapid response(10 minutes to carboxylesterase and a few seconds to pH).The probe was successfully applied to the two-photon imaging analysis of liver cancer cells and liver tissues.The CEMT probe is an effective tool for the visualization of the CE-mediated acidification of cells and tissue,which is of vital significance for the exploration of subcellular environmental changes mediated by enzymes.2.The cross-talk modulation of excited state electron transfer to reduce the false negative background for high fidelity imaging in vivo.We have designed and synthesized a series of fluorescent probes 7-hydroxy-2-oxo-2H-tryptone-3-acetaldehyde-n(HPC-n).Herein,we constructed a fluorophore(F)–electron donor(D)–electron regulator(R)system,and thereby developed a dual modulation strategy for the de novo design of high fidelity fluorescence probes.The probe has the advantages of high sensitivity(a maximum of 140 times),high rate of quantum yield(?max=0.64),rapid response(in a few seconds),ultra-low background,and the specificity to zinc ions.Under this high-fidelity mode,the fluorescence monitoring of zinc ions during the development of liver cancer in mice was successfully performed.The study provides a strategy for designing fluorescent probes with ultra-low background and maximum reporting signal for high fidelity imaging.