Research On The Technique Of Mercury Ion Detection Based On Fluorescent Labeled Hairpin DNA Probes

Environmental pollution has become a global problem,the heavy metal pollution has been paid more attention among these environmental pollution problems,and brought many serious harm to the ecological environment.Hg²⁺ as a kind of heavy metals pollutant caused many pollution problems and diseases,because it was not dissolved in some solvent and widely enrichment in the soil,water and air.At last through food chain or atmosphere it was brought into the human body and damaged the proteins,enzymes activity and organ.Therefore to prevent the mercury pollution problems,disease,food safety crisis and other issues,developing a convenient,quick,sensitive,efficient and can be used in one-site detection is becoming more and more important for human people.The most widely used in the detection of mercury ions is large-scale instruments,such as atomic absorption spectrometry,ICP-MS and so all.These instrument methods have very high sensitivity and good accuracy,but the operation is more complicated,and the time is relatively long.Facing the increasingly complex mercury pollution challenge,to achieve the detection of mercury in different pollution environment,researchers are also developing many new Hg²⁺ detection methods.Such as strip,chemical sensor,nanomaterials sensors and DNA probe,strip is a simple method,but can only do qualitative detection,quantitative analysis can not be achieved,and the other detection methods are basically using chemical molecules or some functional groups can be combined with Hg²⁺,causing the molecular structure or luminescent properties of the molecular changes,finally by observing the fluorescence emission spectrum to achieve quantitative detection of Hg²⁺.Compared with the traditional method,these methods have greatly improved in the operation and cost,but the sensitivity and time needed to improve.In this paper,combined with the characteristics of DNA chain and the fluorescence resonance energy transfer technology,we designed a hairpin DNA chain,and achieved one-step detection of Hg²⁺ at room temperature without tedious temperature processing.The fluorescent dyes Cy3 and Cy5 were modified in the ends of DNA chain,through observing changes of the fluorescence intensity of Cy3,and the linear fitting the changes with the concentration of Hg²⁺.We found that with the increase of Hg²⁺,the fluorescence intensity of Cy3 is increasing,and the linear correlation coefficient between them can reach 0.9836.Moreover,our method can achieve a minimum detection limit of 1.3 nM,lower than the national drinking water standard detection limit of 5 nM.And the selectivity of the method was studied and the interference ions were added.The results show that our method has good selectivity to Hg²⁺ and can be used to specific identify Hg²⁺,which can realize the quantitative detection of Hg²⁺.