Studies On Optical Biosensor Based On Dnazyme Singal Amplification Straregy

Optical analysis and detection method is simple, efficient, high speed, highsensitivity and other advantages. In this thesis, the use of fluorescent and colorimetricdetection signal is as output, based on DNAzyme technology, combined with newmethods to detect biomolecules in recent years, we design two protease molecularrecognition and DNA biosensors, the main works are listed be low:(1) In recent years, scientists have developed many detection method s of T4polynucleotide kinase based on molecular beacons or nano beacons as a signal beaconfluorescence. However, these methods have some limitations, such as they do nothave enough signal amplification cycle reduce the detection limit. To overcome thislimitation, we design and improve these methods. In the original basis, we introducedthe DNAzyme structure. A specific sequence Pb2+-DNAzyme was buried in the newstem loop. Through λ exonuclease auxiliary cutting and release the enzyme to cutmolecular beacons in order to achieve fluorescence signal amplification and improveddetection sensitivity. So it is a very promising sensor.(2) There are two ways to increase the sensitivity of the biosensor: to reducebackground signal or to enhance output signal. Scientists have extensively developedvarious amplification methods to enhance signal output, such as rolling circleamplification; use of gold nanoparticles, carbon nanotubes and graphene oxidequenching the fluorescence signal to reduce the background signal. However, toobtain a low background even zero background is still a big challenge. So far, fewpeople use these two strategies into a system to improve the detection sensitivity. Inthis experiment, we combine these two strategies together successfully to detect T4polynucleotide kinase, and confirm by experiments with a strong signal to noise ratioof the system, so it is a very promising universal type detection platform.(3) Through DNAzyme signal amplification strategy, based on DNA hybridization chain recation, using gold nanoparticles as a signal output, we design astrategy for colorimetric detection of nucleic acids. Because there is no enzymeinvolved in the whole process, the reaction conditions is simple, easy to manipulateand colorimetric detection equipment is easy to observe. Therefore, it is a significantway in application of the biosensor.