Location-activated Fluorescent Probes For Monitoring And Manipulating Cellular Activity

Intracellular microenvironment(such as viscosity,temperature and mitochondrial membrane potential)and biomolecules(such as enzyme and miRNA)are important parameters that affect cellular activity and biological function.Abnormal fluctuations of these parameters may seriously affect the cellular activity and even lead to the occurrence of diseases.Therefore,real-time monitoring these parameters can facilitate early disease diagnosis and immediate therapy.The traditional methods mainly include colorimetric method,electrochemical analysis and gas chromatography methods,however,these methods are difficult to realize spatiotemporal and non-invasive detection of biological sample.Considering that fluorescent probe possesses these advantages of high sensitivity,rapid response and easy synthesis,thus it can realize in situ and nondestructive detection for biological samples in combination with fluorescence imaging technology.Herein,this thesis chooses mitochondrial membrane potential and miRNA as the representative parameters of cellular activity,and then design two kinds of location-activated fluorescent probes for monitoring and manipulating the cellular activity.Mitochondrial membrane potential(MMP)represents an essential parameter of cellular activities,and even a minute MMP variation could significantly affect the biological functions of living organisms.Thus,convenient and accurate MMP detection is highly desirable since conventional MMP probes are always constrained by photobleaching,inconvenience,and irreversibility.Herein,this thesis designs the location-activated fluorescent probe Mito-Cy for efficiently monitoring the varied MMP status.The spatial-dependent fluorescent molecular rotor Mito-Cy is introduced for efficiently tracking the varied MMP status through its restricted intramolecular rotation in mitochondria and nucleus compartments.Based on a systematic investigation,the specifically light up fluorescent Mito-Cy enables to explore different MMP situations by determining their varied distributions.Accordingly,Mito-Cy concentrates in mitochondria under normal MMP status.Yet Mito-Cy starts to migrate gradually from mitochondria to the nucleus in decreasing MMP status,as represented by the increasing distribution levels of fluorescent Mito-Cy in the nucleus.Mito-Cy exclusively accumulates in the nucleus at ultimate vanishing MMP status.The facile operation of Mito-Cy,together with its high photostability and sensitivity,facilitates the monitoring of the reversible and programmable MMP evolutions in living cells.The Mito-Cy-involved logical control over MMP,e.g.,AND and OR logical gates,indicates that the robust and versatile Mito-Cy holds great potential in complex biological environment.miRNA is closely related to cellular activity,which plays an important role in many biological processes,including cell proliferation,cell differentiation and cell apoptosis.Therefore,it is highly desirable to develop in situ signal amplification method for the miRNA analysis due to its trace property.This thesis then introduces the location-activated CHA/BDPI@PLGA-FA nanocapsule for monitoring and manipulating cellular activity.The nanocapsule exhibits efficient targeted delivery and controlled reactants release.Meanwhile,the endogenous mi R-21-driven CHA-Au^I catalysts can successively activate the fluorescent probe BDPI by hydroamination reaction,resulting in the amplified fluorescence feedback and ¹O₂ generation for monitoring and manipulating cellular activity.Thus,the catalysis system activated by diagnostic biomarker is anticipated to be a smart and versatile strategy to explore catalytic transformation processes related with cellular activity,and to formulate more customized therapeutic schedule.