Biosensing Method Research With DNA-related Cycles Amplification Using SERS Detection Technology

In this study, a series of SERS signal amplification biosensing methods weredeveloped with high sensitivity, easy operation and good reproducibility. First, anovel SERS method was designed to detect L-histidine based on DNA amplificationtechnique. The DNAzyme as a molecular recognition module will trigger circularhairpin assisted exponential amplification reaction simultaneously. Second, twokinds of differently modified bio-barcodes were prepared to detect the correspondingtwo kinds of genes based on autonomous target-displacement polymerizationreaction. On this basis, a difunctional aptamer probe was introduced into the systemto detect ATP and lysozyme simultaneously. These SERS biosensing methodprovides a universal method for quantitative analysis of genes, cells and alsoproteins, etc, and supplies valuable information for biomedical research.1. A novel SERS method based on DNAzyme which can specifically recognizeL-histidine is demonstrated in this assay to detect L-histidine. It was confirmed that theunmodified DNAzyme had characteristic of endonuclease as long as it combined withthe target. In the DNA recycling amplification reaction, a large number of bio-barcodeswere indirectly captured on the magnetic beads as the hairpin probes immobilized onthe magnetic beads were constantly opened. The problem of high background inducedby excess bio-barcodes was solved by magnetic separation. The detection limit of0.74nM (3σ) was gained with the amplification of hairpin assisted exponentialamplification reaction. Due to its high sensitivity, excellent specificity and goodperformance in cellular homogenate, it holds great potential for the development ofultrasensitive biosensing platform for the applications in bioanalysis. 2. A sensitive SERS detection method was developed based on hairpin assistedexponential amplification reaction and used to detect two target DNA simultaneously.The amplification process is accomplished by taking advantage of both two kinds ofhairpin assisted exponential amplification reaction. Two different kinds ofbio-barcodes which are modified with Rox and Cy3respectively were prepared whilegold nanoparticles works as the enhanced substrate. The rapid and sensitive analysis oftarget DNA demonstrated the applealing bioanalytical features of this method.3. On the basis of the above work, we proposed a new method for detection ofATP and L-histidine simultaneously. A novel difunctional aptamer which can bothrecognize ATP and L-histidine was first introduced into ultrasensitive SERSbiosensing applications based on the DNA amplification method. Compared with thesecond experiment, two kinds of trigger genes were immobilized on the magneticbeads earlier and then released by the recognition of ATP and L-histidine. The twocycles which were independent and happen simultaneously as an effective amplifiedreplication system were triggered. A large number of biobarcodes were immobilized onthe magnetic beads indirectly. With multiple amplification steps and magneticseparation procedures, this new biosensing system exhibits high sensitivity andspecificity.