Study On Dna Biosensor For Detection Of Genetically Modified Organisms Based On SPR And Electrochemistry

With the rapid development and application of transgenic technology in the fields of genetic breeding and agriculture,the type and number of genetically modified products are gradually increasing,and their safety has become the focus of public opinion.At present,the classical and standard methods for the detection of genetically modified crops are nucleic acid analysis,such as qualitative PCR,real-time fluorescence quantitative PCR and digital PCR.The advantage of these methods is that most testing laboratories can meet the conditions of instruments and equipment.The disadvantage of these methods is that they need to amplify the signal by PCR amplification,most of them belong to the time-consuming end-point method,and the components after reaction can not be reused.Therefore,the innovation and development of genetically modified organisms detection technology are extremely urgent.In this study,the terminator of nopaline synthase gene(t-nos)transgenic element was selected as the detection object,and an unlabeled multiple dimensions(MD)DNA probe electrochemical(EC)sensor strategy was successfully developed.Using electrochemical sensing technology,a MD DNA probe(composed of an intermediate poly A sequence and two flanking capture probes at both ends)was designed,and the construction of the whole system,assembly conditions,specificity,sensitivity,stability and regeneration of the MD DNA probe were studied.Among them,the poly A fragment in the middle showed good assembly ability on the surface of the gold electrode,which improved the repeatability,stability and reproducibility of the biosensor.The poly A sequences of different length were compared during the experiment.When the length of the poly A fragment was 30 nt,the highest signal-to-noise ratio(S/N)was obtained.Through the detection of the gradient diluted target DNA,the detection limit(LOD)finally reached 10 f M,and the working range was from 10 f M to 1 n M.As a new interface assembly strategy,the MD DNA probe method greatly reduced the economic cost of probe design,and the function could be easily expanded by modifying the probe sequence.At the same time,the electrochemical part was characterized and verified by surface plasmon resonance(SPR).The results showed that it was basically consistent with the experimental results of electrochemistry,although the detection limit was slightly lower than that of electrochemical methods,which was only 1 pm,but it played a role in real-time monitoring.Through this combined verification method,a multi-dimensional electrochemical-surface plasmon resonance(EC-SPR)detection method with high specificity and high sensitivity was constructed for the analysis of genetically modified samples,and then a new biosensor method that is fast,sensitive,label-free and renewable was developed,which provided a reliable experimental and technical basis for the research of new genetically modified organisms detection technology.