A label-freeandhighlysensitiveelectrochemicalaptasensorforPb2þ wasconstructedusingthionine
(TH) asthesignalingmoleculeandgraphene(GR)asthesignal-enhancingplatform.Theelectrochemical
sensing interfacewasfabricatedbystepwiseassemblyofGRandTHonthelead(II)specific aptamer
(LSA)modified electrode.UponinteractionwithPb2þ, theaptamerprobeonthesensorunderwent
conformational switchfromasingle-strandedDNAformtotheG-quadruplexstructure,causingtheGR
with assembledTHreleasedfromtheelectrodesurfaceintosolution.Asaresult,theelectrochemical
signal ofTHontheaptasensorwassubstantiallyreduced.Undertheoptimalexperimentalconditions,
the attenuationofpeakcurrentspresentedagoodlinearrelationshipwiththelogarithmofPb2þ concentrations
overtherangefrom1.61013 to 1.61010 M. Thedetectionlimitwasestimatedtobe
3.21014 M. Theaptasensoralsoexhibitedgoodregenerability,excellentselectivity,andacceptable
reproducibility,indicatingpromisingapplicationinenvironmentmonitoringoflead.