Application Of DNA Fluorescence Biosensor In Melamine Detection And T-Hg²⁺-G Performance Research

Biosensors have the advantages of high sensitivity,good selectivity,and easy operation,making them gain a wide attention in the fields such as environmental monitoring,food safety and disease diagnosis.Improving the sensitivity and specificity of biosensors has been a serious challenge for researchers.The emergence of functional nucleic acids has opened up new ideas and options for the construction of highly sensitive and specific biosensors.Therefore,systematic investigation of the binding ability of functional nucleic acids to specific molecules is an important prerequisite for their use in target analysis and detection,as well as an important reference for their practical application value.In addition,the detection sensitivity of the biosensor can be further optimized by combining functional nucleic acids with novel nanomaterials.As a result,the following work was carried out in this paper:1.A new method for melamine detection based on GO and triple stranded DNA.Firstly,graphene oxide（GO）was successfully prepared and characterized.Then,Based on the excellent fluorescence quenching performance of GO and the pecific binding capacity of three-stranded DNA containing abasic sites,combined with the hydrolysis performance of exonuclease III（ExoⅢ）,a new method for the specific detection of melamine with amplified detection signal was constructed.This method has excellent selectivity and sensitivity compared with many reported methods.The detection limit was0.32 nmol/L for melamine.Compared with the traditional electrochemical method,this method does not involve complicated steps such as washing and separation,and has the advantages of simplicity,convenience and high sensitivity.2.Study on T-Hg²⁺-G binding properties and its application in biosensor analysis.Three fluorescent molecule labeled DNA probes containing different numbers of T-T or T-G mismatches were designed,and the binding kinetics of T-T or T-G mismatched bases to Hg²⁺,followed by the systematical research of the sensitivity and selectivity for Hg²⁺detection.The experimental results showed that T-T mismatched bases had faster signal response kinetics to Hg²⁺,while T-G mismatched bases had higher sensitivity to Hg²⁺.In addition,the application of analytical strategies based on the T-Hg²⁺-G structure in biomolecular analysis and detection was studied by using glutathione（GSH）as a model.The results showed that the detection limit was 18.96 nmol/L for GSH.This resaerch provides a great reference and help to further interactions between Hg²⁺and nucleobases and extend the applications of Hg²⁺-mediated base pairs.