Mirna Detection And Targeted Drug Release Based On Multifunctional DNA Probes

Rapid early diagnosis of major diseases and accurate targeted therapy are still important research directions nowadays.In this paper,biocompatible nanomaterials are combined with surface-enhanced Raman scattering technology and fluorescence detection technology,and meanwhile,microfluidics technology and logic gate operation are skillfully utilized to achieve rapid and accurate detection of microRNA(miRNA),an active molecule associated with major diseases,and targeted drug delivery for tumor tissues.This paper mainly consists of the following three parts:(1)A target-triggered mutually amplified signal(TMAS)probe that can be stimulated was designed,and a surface-enhanced Raman scattering(SERS)-microfluidics platform with enrichment and signal enhancement effects was used to achieve rapid signal amplification detection of tumor markers miRNA.The scheme combines the advantages of the traditional Raman signal amplification strategy and the microfluidic technology based on AC power.In the presence of target chain miR-21,the enzyme-free target-strand displacement recycling signal amplification(TS-DRSA)reaction is activated,and the TMAS probe and the target are continuously concentrated toward the central electrode under the enrichment effect of microfluidic electrode.Under the dual signal amplification effects of cyclic amplification reaction and microfluidic electrode,the target signal strength is rapidly improved,and the detection limit reaches 2.33 fM under the optimal reaction condition.This method is simple and rapid,with a detection time of 0.5h,high sensitivity and good selectivity,and can be used for the determination of miR-21 in cell homogenate of actual samples.(2)A signal transformation strategy based on DNAzyme was constructed,and the target miRNA was accurately detected using DNA cyclic amplification technology and microfluidic technology.This scheme introduced the special structure of DNA enzyme and the design concept of double-beacon DNA,and realized the detection of target chain miR-141 in homogeneous solution.After miR-141 successfully activated the signal transformation reaction,the two signals changed in a pattern of one increase and one decrease,overcoming the problem that traditional single signal source is prone to appear accidental errors.At the same time,the absolute value coupling processing of the two kinds of data further reduces the background signal and realizes the trace detection.This scheme provides an effective method for the rapid and sensitive quantitative detection of other biological molecules.(3)A hollow gold nanocage that can be loaded with DOX,an anticancer drug,was synthesized,and the gold nanocage was combined with the traditional DNA chain substitution reaction to construct a controlled DNA logic gate with double input and single output.In this system,a self-assembled DNA probe containing G tetrad structure was designed with dual functions of blocking drug and identifying probe and modified on the surface of gold nanocage.Taking two target miRNAs as input signals and fluorescent DOX as output signals not only realizes the effective construction of logic gates,but also ensures that the carrier can effectively deliver anti-cancer drugs to cancer tissues,thus realizing the combination of DNA logic circuits and cancer diagnosis and treatment.