Preparation Of DNA Nanoprobes Based On Chitosan/Silica Nanoparticles And Their Electrochemiluminescence Analysis Characteristics

Traditional molecular recognition reaction,such as antibody binding antigen,enzyme recognition substrate,etc,required the special reaction condition,which partly limited their widely analytical application.To overcome these limits,DNA probe was developed for molecular recognition and were widely used to detect different targets.However,in these reported schemes,DNA probe molecules need to be labeled with other signal molecules,which are complex,consuming,high cost and also interfered the recognition ability of the DNA probes to target.In order to solve these problems,DNA nanoprobe was developed by immobilizing DNA probes on the surface of nanomaterials.Since many nanomaterials could be used to design DNA nanoprobe,the DNA nanoprobe has been used to detect different targets with the high sensitivity.But the procedure of immobilizing DNA probe on nanomaterials was still needed,which also limited its analytical performances.Thus,the development of label-free,immobilization-free DNA nanoprobe prepared method is very important.The research work of this paper is mainly about this problem,its composed of review and research report.In review section,we introduced the concept and characteristics of DNA nanoprobe,mainly explained the advantages of luminescence analysis combined with DNA nanoprobe and their applications in analys.Research report consists of the following two parts:1.The preparation and electrochemiluminescence application of the DNA nanoprobe based on Rubpy32+/chitosan/silica nanoparticlesThis work prepared a lable-free DNA nanoprobe based on the electrostatic adsorption and hydrogen bonding force between Rubpy32+/chitosan/silica nanoparticles and the phosphate skeleton of DNA,and characterized the DNA nanoprobe by several methods.The result shows that the prepared DNA nanoprobe has certain stability and good signal reproducibility.On this basis we use this DNA nanoprobe for the detection of miRNA and researched their analysis application.With the absence of target miRNA,CRuS NPs warpped by DNA probes show electrically neutral,only a small amount of CRuS NPs could be adsorbed at the negative charged Nafion/MWNTs modified GCE and produce ECL signal.However,while target miRNA presence,DNA probes on the surface of CRuS NPs could hybridize with target miRNA,forced the DNA probes away then formed rigid structured double stranded DNA-miRNA products and naked CRuS NPs.In this case,based on the strong affinity interaction of CRuS NPs with the Nafion film,these naked CRuS NPs could effectively adsorbed on the Nafion/MWNT modified electrode and produce a stronger ECL signal.Experimental results prove that the DNA nanoprobe could recognize target miRNA with high sensitivity,high selectivity and detect miRNA as low as 0.03 pM.It also was successful used in the detection miRNA in human serum sample.2.The preparation of DNA nanoprobe based on chitosan/lueigenin/silica nanoparticles and electrochemiluminescence detecting miRNALueigenin is a traditional reagent for chemiluminescence(CL)and electrochemiluminescence(ECL)analysis.This work prepared DNA nanoprobe used chitosan/lueigenin/silica nanoparticles(CLS NPs)as substrates and use this DNA nanoprobe for the detection of miRNA.Lueigenin embedding in the inside of the silica nanoparticles can not produce ECL because it was isolated from test medium.In order to solve this problem,we enable the ECL of CLS NPs effectively in sodium hydroxide solution by in situ etching CLS NPs by HF on the modified electrodes,thus high sensitivity could achieve when CLS DNA nanoprobe was used to recognize target miRNA.The CLS DNA nanoprobe appears good specificity for miRNA.The results showed that the ECL intensity was directly linear to the the concentration of target miRNA in the range from 1.0-9.0pM,and CLS DNA nanoprobe was successful applied to the detection of target miRNA in human serum sample.