Construction And Detection Of Electrochemical DNA Sensor Based On Novel Signal Molecules

Deoxyribonucleic acid(DNA)is the universal genetic material that encodes biological information in organisms.Determination and quantification of specific DNA sequences,especially for the diagnosis of cancer are more and more important.However,there are no obvious symptoms in the early stages of cancer,and diagnosis cannot be made until the middle or late stages.Therefore,early detection,early diagnosis and early treatment of cancer are of great significance to improve the cure rate of cancer and reduce mortality.In order to cure cancer effectively,early diagnosis and even advanced prediction of related cancers can be carried out at the genetic level.At present,many detection methods have been found to detect DNA,including fluorescence,electrochemical luminescence,enzymatic,surface plasmon resonance,colorimetry and so on.Electrochemical sensors have received widespread attention due to their advantages of low cost and portable devices,which have great application prospects in nucleic acid detection.There are two parts in this study:(1)simple and rapid detection of DNA using Zr(IV)as signal molecule;(2)The sensitivity of the sensor is improved by signal amplification strategy.1.Highly sensitive determination of DNA via a new type of electrochemical Zr(IV)signaling probeIn this strategy,an electrochemical sensor for simple and rapid detection of DNA was constructed with Zr(IV)as the signal molecule and PNA as the capture probe.Firstly,the PNA probe was immobilized on the the surface of glassy carbon electrode(GCE)to capture the target DNA(t DNA).In the presence of t DNA,Zr(IV)signal molecules labeled on phosphate groups of DNA via coordination interaction,and stoichiometrically labeled Zr(IV)probes can be detected via differential pulse voltammetry(DPV).There are no phosphate groups on PNA,which renders low background noise.Under the optimal conditions,this strategy showed a good linear response between 0.01 n M and 100 n M t DNA,and the detection limit was 0.81 p M(R~2=0.998).In addition,the biosensor had been successfully applied to the detection of DNA in serum samples with satisfactory results and showed great potential in clinical analysis.2.Electrochemical detection of DNA via reversible addition-fragmentation chain transfer polymerization(RAFT)based on TEMPO as catalyst and Fc as signal moleculeIn this work,HS-PNA probes were self-assembled onto gold electrode for the capture of t DNA fragments,and then PNA-DNA-Zr⁴⁺-CPAD(4-cyano-4-(phenylcarbonothioylth)pentanoic acid)was formed via the phosphate-Zr⁴⁺-carboxylate.In this study,TEMPO was used as the catalyst of RAFT and ferrocene(Fc)was used as the monomer.At the same time,the oxidation current of Fc was detected by square wave voltammetry(SWV),and then the concentration of DNA was analyzed further.We hope to obtain a sensor with higher sensitivity than that of the first experiment,and it will play an important role in practical applications.