Sensitive Detection Of MiRNA-21 Based On CHA Method On The Surface Of Microtube

MicroRNAs(miRNAs)are a class of typical,small,non-coding single strand RNA molecules(containing about 22 bases),which are encoded by endogenous genes.They are involved in gene expression and regulation during post-translational in animals and plants.It is of great significance in life bodies.MiRNAs have been regarded as new biomarkers for early cancers diagnosis and disease prevention,since the variation of miRNAs expression levels were found to be directly related to many diseases.It has become a research focus in recent years to detect miRNAs efficiently and rapidly in complex biological environment.Fluorescence based methods have been widely used in the detection of biochemical molecules(such as DNA and enzyme)due to their high sensitivity and easy operation.Nevertheless,the traditional fluorescence methods possess some inevitable defects,including low stability and spectra cross-talk with background fluorescence in complex biology environment such as human serum,which restrict its practical use.To address these problem,our group previously developed single polydiacetylene(PDA)microtube optical waveguide system for sensitive detection of miRNA.In the one dimensional PDA microtube waveguide system,in which the emission excitation and out-coupled positions were far apart,could effectively reduce the background fluorescence interference.Considering that Au@PDA microtubes were unstable in buffer for long-term storage,we developed a novel 1D PDA microtube waveguide platform which integrated with sandwich-structure design.In this strategy,the formation of sandwich structure simplifying the reaction and preparation process,improving the reaction efficiency,and enhancing the stability and recyclability of the platform,which is meaningful for developing novel miRNAs quantification techniques for early clinical diagnosis of diseases.In order to achieve ultrasensitive detection of target molecules in complex envioronment,a number of signal amplification strategies have been designed by scientists,such as catalyzed hairpin assembly(CHA).Unfortunately,two hairpin probes in a CHA circuit can potentially react non-specifically even in the absence of target,and the.non-specific background leakage degrades the signal-to-noise ratio,preventing application of CHA at ultralow concentration miRNA analysis.To solve this problem,we designed an amino-functionalized PDA microtube integrated with heterogeneous CHA amplification strategy.We demonstrated that the performance of strand displacement nucleic acid circuits on the surface of PDA microtube could be improved,while the background signal would be successfully suppressed.It is remarkable that the proposed PDA microtube biosensor could be applied to discriminate cancer patients from healthy people by direct and rapid analysis of miRNAs in human serum.This work not only provides PDA microtube materials toward practically miRNA detection in complex biological environment but also is of great fundamental value for rational design of CHA based probes for medical point-of-care applications.