| dc.description.abstract | With excellent electrical properties such as high electrical conductivity and carrier mobility, large-area graphene grown by chemical vapor deposition (CVD) technology, which was widely used as the sensing material of bio-sensing platform. By forming a π-π bonding between graphene and the benzene structure of DNA, a label-free and non-functionalized graphene could be realized by use of graphene as the platform material which could significantly simplify the process of the currently used bio-sensing applications. However, several issues such as the cumbersome preparation of fluorescent sensing, the affected detection accuracy of liquid-gate field-effect transistor (FET) due to the formation of double layer capacity, and the relatively long sensing time caused by the electrostatic repulsion between graphene and DNA were still remained and need to be solved urgently. As for the detection mechanism, considering the complex affection of charge transfer and electrostatic effect of graphene, related kinds of literature were still lacking and further research was needed to be clarified.
In this study, a label and functionalize-free graphene-based Epstein-Barr Virus (EBV) DNA sensing device was prepared by the CVD method and followed by the Hall measurement, which could effectively avoid the affection of voltage consumption due to the double layer capacity. In addition, the detection mechanism was further explored and investigated by the measurement of surface charging. Moreover, the electrophoretic adsorption method was introduced to solve the electrostatic repulsion issue. The research results show that with the electrophoretic adsorption, the effective sensing range from 1 pM to 10 nM was achieved together with a low detection limitation of 1 pM and the high reliability of 0.94. Moreover, for the first time, a novel surface zeta potential measurement was used to investigate the conditions of charging accumulation after the immobilization of probe DNA and the hybridization of target DNA, ranging from -24.47 to -29.42 and -33.05 mV, respectively. This could help to explain the sensing mechanism in this study Also, electrophoretic adsorption is used to reduce the influence of electrostatic repulsion between DNA and graphene and probe DNA and target DNA by shortening the sensing time from 18 hours to about 5 minutes. | en_US |