A novel label-free electrochemical miRNA biosensor using methylene blue as redox indicator: application to breast cancer biomarker miRNA-۲۱

چکیده مقاله

Small noncodingmicroRNAs(miRNAs)haveemergedasidealnoninvasivebiomarkersforearly-phase cancer detection.Inthisreport,alabel-freeandsimpleelectrochemicalmiRNAbiosensorisdeveloped based onemployingmethyleneblue(MB)asaredoxindicator.Thesuccessfullyimmobilizationofthe single strandDNA(ss-DNA)probeandhybridizationwiththetargetmiRNAsequencewereconfirmed by electrochemical impedancespectroscopy(EIS)andcyclicvoltammetry(CV)methods.Differentialpulse voltammetry (DPV)techniquewasusedtorecordtheoxidationpeakcurrentofMBunderoptimal condition andanincreaseinthepeakcurrentwasobservedafterhybridization.Byemployingthis strategy,miRNAcandetectinarangefrom0.1to500.0pMwitharelativelylowdetectionlimitof 84.3 fM.TheelectrochemicalresponseofMBonss-DNAandduplexofmiRNA/DNAwascharacterizedby CV andchronocoulometrymethod.Thelinearrelationbetweentheredoxpeakcurrents(Ip) andscanrate (ν) indicatesthattheelectrontransfer(ET)betweenMBandtheelectrodesurfacewasmediatedbythe miRNA/DNA π-stackedduplex.Thevalueofsurfacecoverage(Γ) wascalculatedthatindicatedincrease amount ofMBonthesurfaceofmodified electrodeafterhybridizationeventandrevealedtheadsorption of MBatmodified electrodeismonolayer.Also,theelectrontransferrateconstants(ks) ofMBwere estimated. Theresultsofkineticanalysiswereconfirmed bychronocoulometrymethod.Thedis- crimination abilityofmiRNAbiosensorevenagainstanoncomplementarytargetwasalsostudied. Consequently,thisstrategywillbevaluableforsensitive,selectiveandlabel-freedetectionofmiRNA.v