Construction And Application Of A Three-stage Electrochemical DNA Sensor With Quantum Dots Double Enhancement

In this paper,we present an efficient,rapid and accurate electrochemical DNA biosensor based on NaOH-etched glassy carbon electrode,three-segment DNA hybridization structure and double-enhanced CdTe QDs for detection of P53 gene.The electrochemical performance of the sensor was characterized by cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS)and differential pulse method(DPV).The experimental results show the detection limit of electrochemical DNA sensor reached 4.153x10-13 M(38,n=5),and it has excellent selectivity for P53 tumor suppressor gene.In this paper,we present a simple and sensitive electrochemical DNA biosensor based on graphene oxide(GO)/chitosan(CS)hybrid nanocomposites modified glassy carbon electrode(GCE)for detection of Escherichia coli ATCC25922.Cyclic voltammetry investigations indicated that the GO/CS/GCE showed excellent electron transfer ability and good linear relation.In the experiment,we cultured and extracted DNA of the E.coli ATCC25922 strains and used prepared sensor detect the target DNA.The results show that the sensor has a lower limit of detection of its standard DNA detection limit reached 3.58410-15 M,the limit of detection of viable bacteria reached 50 cfu/L.The hybridization of target DNA with different mismatched bases showed that the prepared electrochemical DNA sensor has excellent specificity.In this paper,we used carboxylated carbon nanotubes and quantum dots as modified material to construct the sensor.The bare Au electrode modified with materials were preliminarily characterized with electrochemical method.The results showed that the carboxylated carbon nanotubes played the role of electrochemical signal amplification on the electrode surface and could provide more active sites for the immobilization of single-stranded DNA probes.