Design,Synthesis And Properties Of Near Infrared Fluorescent Probes Based On Biological Microenvironment And Enzyme Detection

The microenvironment involves viscosity,polarity,temperature,redox and acid-alkaline conditions.The intracellular microenvironment is greatly heterogeneous and has different compositions at distinguishing locations.In the cytoplasm,subcellular organelle or membrane system,the microenvironment of each site plays an important part in many biological processes,such as intracellular transport of energy and quality,transduction of distinguishable signals,the interplay between biological macromolecules(proteins),and cellular metabolic rates.Based on the requirement of microenvironment viscosity identification,we designed and synthesized a novel near-infrared fluorescent probe(V-M1)with 1,8-naphthylamide derivative as the main structure for detecting mitochondrial viscosity mitochondria.After testing the UV and fluorescence spectral properties of V-M1 in different viscosity systems,the probe V-M1 was found to have the ability to accurately monitor viscosity changes in the solvent system.In addition,the fluorescence imaging of HeLa cells and C.elegans showed that probe V-M1 has the ability to detect changes in cell microenvironment and viscosity in vivo.In this paper,we utilized the 4-Diethylamino-2-hydroxybenzaldehyde and 1-(4-(Dimethylamino)phenyl)ethanone as the main frame to synthesize a NIR fluorescent probe(V-P1)for detecting the viscosity of microenvironment and labeling the G-quadruplex RNA in the nucleus.By analyzing the fluorescence spectral data of V-P1,it was confirmed that the probe has the ability to accurately monitor the viscosity change in the solvent system and to recognize the G-quadruplex RNA.In addition,V-P1 fluorescence imaging of HeLa cells,C.elegans and zebrafish showed that the probe V-P1 can not only accurately label the nucleus,but also monitor the viscosity changes in the organism and cell.All results indicated that V-P1 is a novel multifunctional fluorescent probe which having great potential of bioapplication.Enzyme is a kind of macromolecular biocatalyst that can accelerate chemical reactions.The substance used for the enzyme is called a substrate,and the different substances which from the enzyme converting the substrate are called products.Almost all intracellular metabolic processes rely on enzyme catalysis to occur at a fast enough rate to maintain normal life activities.Based on the requirement of detecting specific enzyme,a novel NIR fluorophore was developed and a new leucine aminopeptidase(LAP)fluorescent probe(NIR-LA)was synthesized by linking leucine to this fluorophore.After reacting with LAP,the NIR-LA was confirmed to have the ability of monitoring changes of LAP which existing in the solvent system by analyzing UV absorption and fluorescence changes.Fluorescence imaging of HeLa cells and C.elegans exhibited that the probe NIR-LA has the ability to monitor the LAP changes in organisms and cells.