Detection Of DNA And Protein By Quartz Crystal Micro Balance Based On The Technique Of Isothermal Signal Amplification

In this article, a series of novel quartz crystal microbalance assay systems were developed for ultrasensitive detection of nucleic acids and protein based on the rolling circle amplification technology, hybridization chain reaction and enzyme assisted cascade amplification strategy. Moreover, the proposed strategies exhibited an excellent speci?city, the detailed content was described as follows:1. A novel quartz crystal microbalance(QCM) assay is demonstrated to selectively and sensitively detect the DNA and lysozyme.The detection process consists of aptamer recognition strategy, rolling circle amplification and biocatalytic precipitation. With the involvement of an aptamer-based complex, ampli?cation reaction templates and biotin-functionalized signal probes, the whole ampli?cation process is triggered by the target recognition of lysozyme. After hybridized with the hairpin, the rolling amplification reaction are triggered by the action of restriction enzyme. As a result of RCA reaction, a large number of HRP are captured on the electrode surface which further stimulate the biocatalytic precipitation(BCP) onto the electrode surface for signal amplification, producing insoluble products on the electrode surface that changes the frequency greatly.2. Detection of ultralow concentrations of specific nucleic acid sequences is a central challenge in the early diagnosis of genetic diseases and biodefense applications. Herein, we report a simple and QCM method for ultrasensitive DNA detection. It is based on the exonuclease III(Exo III)-assisted cascade signal amplification and the catalytic effect of hybridization chain reaction. A primer DNA probe hybridizes a hairpin DNA probe to construct a duplex DNA probe as recognition element. Upon sensing of target DNA, the recognition of target DNA and the duplex DNA probe triggers the Exo III cleavage process, accompanied by releasing target DNA and generating a recycle amplification. Subsequently, the released primer DNA could be captured on the surface of electrode which further catalyze the hybridization chain reaction. As a result of HCR, a number of streptavidin modified gold nanoparticles was captured on the electrode which changed the frequency greatly. This method exhibites a high sensitivity for DNA detection and holds a great potential for early diagnosis in generelated diseases.3. A self-assembled DNA nanostructure as an effcient signal ampli?er was introduced to create a simple quartz crystal microbalance biosensing platform for highly sensitive and selective detection of nucleic acids. The ampli?cation process consists of hybridization chain reaction(HCR) and the biocatalytic precipitation(BCP). Upon the recognition of the molecular beacon(MB) to target DNA, the target DNA could propagate a chain reaction of hybridization events between the two hairpin probes, and where long nicked DNA polymers could be formed on the modi?ed electrode. Then the biotin-labeled dsDNA polymers could introduce numerous avidin-labeled horseradish peroxidase( HRP), which would further stimulate the biocatalytic precipitation(BCP) onto the electrode surface for signal amplification, producing insoluble products on the electrode surface that changed the frequency greatly. As the result of the multisignal amplification in this HRP catalyzed BCP-based aptasensor, the QCM signals were significantly enhanced.