Construction Of MiRNA In Situ Imaging And Upconversion Photodynamic Therapy Based On ATP-Driven Cyclic Amplification Strategy

Cellular miRNAs are related to the occurrence and metastasis of tumors.Therefore,the detection and imaging of intracellular miRNAs play an important role in the diagnosis and treatment of tumors.However,the abundance of miRNAs in cells is very low,small in size,high in homology,and easy to degrade,which brings certain challenges to their sensitive detection.The use of endogenous marker stimulation-response strategies can effectively improve the accuracy of in situ imaging of intracellular miRNAs and mediated cancer therapy,and reduce the normal intracellular signal background and toxic side effects.Simultaneous photoactivation design can provide temporal and spatial high precision for imaging and therapy.In this paper,upconversion nanoparticles are used as the transport carrier of the cyclic amplification system,and endogenous ATP is used as the cyclic power to realize the stimulation-responsive cyclic amplification process in tumor cells,and improve the signal-to-noise ratio and sensitivity of in situ imaging of target miRNAs in tumor cells.In addition,up-conversion nanoprobes have the characteristics of long luminescence lifetime,adjustable emission spectrum,good photostability,less damage to biological tissue,deep tissue penetration ability,and small background fluorescence signal,etc.,and have been widely used in tumor diagnosis and treatment in recent years.In this paper,a miRNAs stimulus-responsive up-conversion photodynamic therapy system was further constructed to improve the tissue penetration depth and therapeutic ability of the tumor site,and provide an effective and referential strategy for the precise diagnosis and treatment of tumors.The main research work of this paper is as follows:1.Construction of upconversion fluorescent probes for in situ imaging of light-controlled miRNAs based on intracellular ATP-driven cyclic amplification strategy.Light-sensitive DNA-modified upconversion nanoparticle(UCNPs)was constructed to construct light-controlled,stimuli-responsive fluorescent probes.This probe utilizes a photocleavable DNA strand to block the miRNAs recognition region to prevent non-specific extracellular activation.Under the near-infrared light of ATP,after the ultraviolet light emitted by UCNPs cleaves the photosensitive group,the endogenous miRNAs specifically binds to the recognition region on the stem-loop DNA,opens the stem-loop DNA,binds to the DNA quenching chain,and releases the signal DNA.Further,under the stimulation of the highly expressed small molecule ATP in the cell,the DNA quenching chain is bound and freed from the stem-loop DNA,so that the recognition site of the stem-loop DNA re-recognizes DNA,releases the signal DNA again,and realizes the recognition of the signal DNA.Cyclic zoom.This strategy uses light control and endogenous stimulation strategies to improve the controllability and accuracy of miRNAs imaging in tumor cells,effectively avoiding the signal background caused by a small amount of miRNAs in normal cells and blood caused by the circulating system,and providing a new source of miRNAs in tumor cells.High-precision spatiotemporal imaging provides an effective strategy.2.Construct a controllable,high-precision up-conversion photodynamic therapy probe based on an endogenous stimulation strategy.A stimuli-responsive upconversion photodynamic therapy research system was constructed by using DNA design.The photosensitive group is preprotected by luminescence resonance energy transfer strategy.Under the stimulation of highly expressed ATP and miRNAs in tumor cells,the loop amplification is triggered and the luminescence resonance energy transfer process is broken.Under near-infrared light stimulation,the emitted light of up-conversion nanoprobes can effectively excite photosensitizers and realize up-conversion photodynamic therapy.The combination of up-conversion nanoparticles,miRNAs-induced cyclic amplification process,and endogenous small molecule drive of tumor cells will improve the penetration ability of diagnostic and therapeutic probes into tumor tissue and the high precision of treatment,effectively avoiding the impact of diagnostic and therapeutic probes on surrounding areas.The toxic and side effects of normal tissues provide an effective strategy for the construction of high-precision tumor diagnosis and treatment strategies.