Perylene derivative-bridged Au-graphene nanohybrid for label-free HpDNA biosensor

Along with the challenges of wet-chemically preparing graphene-based nanohybrids, for example easy aggregation, low-stability in solution environment and insufficient loading amount, here we report the preparation and application of a type of π-conjugated molecule, perylenetetracarboxylic acid di-imide (PDI)-functionalized graphene material with high density of gold nanoparticles (AuNPs). In this nanohybrid, the PDI molecule comprises five-connected benzene rings and positively charged terminals composed of two symmetrical imidazole rings and amine groups, which offers the intrinsic driving force for π-π interactions with graphene and also serves as the active sites for immobilization of AuNPs. Transmission electron microscopy results demonstrated that AuNPs were uniformly dispersed and densely covered the PDI-functionalized graphene compared to the control experiment without PDI. To prove its biological application, the Au-PDI-graphene nanohybrid was chosen as a sensing material for fabricating a label-free electrochemical impedance hairpin DNA (hpDNA) biosensor for detection of human immunodeficiency virus 1 gene. When hpDNA was hybridized, it exhibited a sensitive electrochemical impedance variation on an Au-PDI-graphene modified electrode. This fabricated hpDNA biosensor reveals a wide linear detection range and a relatively low detection limit. Thanks to its high stability and efficient electrochemical impedance sensitivity, this nanohybrid would offer a broad range of possible DNA sequences for specific applications in biodiagnostics and bionanotechnology.