Electrochemical Aptamer Sensor Based On Dual Signal Strategy

Disease markers are specific biochemical indicators of objective testing and evaluation of a normal biological process,pharmacological or pharmacological response during treatment,which can be used for disease diagnosis,disease surveillance and disease classification,as well as an important basis for drug screening.However,most of disease markers in human tissue and body fluids were very low,making it difficult to be accurately detected in real samples,which greatly restricts the application of detection of disease markers in clinical practice.Electrochemical aptasensors are widely used,because of their high sensitivity,specificity,quick response,and easy to be miniaturized and integrated.In order to the ultrasensitive detection of disease markers in the real sample,we design two kind of dual signal electrochemical aptasensors through dual signal strategies,which can be applied in the simple,rapid and accurate detection of lysozymes.It is significant for prevention,early detection and therapy monitoring of some major diseases.The integration of“signal on/off' and "labeling/label-free" strategies was applied in the fabrication of a sensitive and selective dual-signalling electrochemical aptasensor.Ferrocene(Fc),being labeled on single stranded DNA as one signal indicator,could provide "turn on" signal.[Ru(NH3)6]3+(RuHex),as another signal indicator,could provide label-free and "turn off' signal through the electrostatic interaction between the anionic DNA phosphate backbones and the cationic RuHex.Based on the superposition of the dual signal changes(|?IRuHex| +?IFc),the sensitivity of this aptasensor for lysozyme detection was improved compared to individual signal.The detection limit was down to 0.8 pM.In this work,a new sensing scheme for protein detection was presented based on converting liquid-phase colorimetric assay into enhanced surface-tethered electrochemical analysis.In order to accomplish this conversion,we designed a colorimetric aptasensor and an electrochemical aptasensor for lysozyme detection by using the same AuNPs-DNA sensing units and construction principle,which was the target-induced AuNPs-DNA sensing units accumulation strategy.Compared with the colorimetric aptasensor(linear range:5 nM-500 nM,detection limit:0.9nM),the improved electrochemical aptasensor is more sensitive.Furthermore,it also has the superiority of simple principle and easy operation.This electrochemical aptasensor presents a low detection limit of 0.3 pM for lysozyme,wide linear range(from 1 pM to 10 nM),excellent specificity and applicability in serum samples.