Direct, sequence-specific detection of dsDNA based on peptide nucleic acid and graphene oxide without requiring denaturation

Abstract

Sequence-specific detectionofdoublestrandedDNA(dsDNA)isimportantinvariousresearch fields. In general,denaturationofdsDNAintosinglestrandsisnecessaryforthesequence-specific recognitionof probes totargetDNA,posingseveraldrawbackswhichdecreasetheefficiency asaDNAsensor.Herein, we reportadirect,sequence-specific dsDNAdetectionsystemwithoutrequiringanythermaldenaturing step. Ourstrategyutilizespeptidenucleicacid(PNA)andgrapheneoxide(GO)asaprobeandasa fluorescence quencher,respectively.ThePNA first bindstotheendofdsDNAstrandduetotherelatively easily dissociableterminalbasepairsofDNAduplex.Next,superiorbindingaffinity ofPNAtowards complementary DNAinducesbranchmigrationforgradualstrandreplacement,resultinginthe formation ofPNA/DNAduplex.UnlikeotherdsDNAsensorsbasedoncomplementaryDNAprobes,PNA in combinationwithGOenabledhybridizationwiththetargetsequencehiddenasaduplexformwithout denaturing stepandthus,theformationofPNA/DNAduplexwastranslatedintoselective fluorescence signal. Moreover,itprovidedtighterturn-onsignalcontrolwithverylowbackgroundsignalandhigh sensitivity andsequenceselectivityeveninthepresenceofserumproteins.