Study On Graphene Oxide And DNA Nanostructure For Nudeic Acid Detection

Nucleic acids play a vital role in the biological genetic, growth and variation, which are one of the most important tumor markers. This paper proposed graphene oxide (GO)-based chemiluminescence resonance energy transfer (CRET) mechanism and hyper-branched chain reaction for sensitive and selective detection of microRNA and DNA.This thesis can be summarized as the following two parts:1. Hot-spot-active magnetic graphene oxide substrate for microRNA detection based on cascaded chemiluminescence resonance energy transferIn this chapter, graphene oxide (GO)-based chemiluminescence resonance energy transfer (CRET) mechanism was propsoed, which was applied to microRNA detection. Firstly, MGO was synthesized through covalent reaction between GO and amino magnetic beads. Then, the proposed cascaded chemiluminescence resonance energy transfer (C-CRET) system was successfully implemented to construct three modes of C-CRET hot-spot-active substrate by covalently immobilizing HRP-mimicking DNAzyme/fluorescein-labeled hairpin DNAs on magnetic GO (MGO), resulting in a signal "off" state due to the quenching of luminol/H2O2/HRP-mimicking DNA:zyme/fluorescein CRET system by GO. Upon the introduction of microRNA-122, an "open" configuration of hairpin probe and a CRET signal "on" state were caused, achieving sensitive and selective detection of miRNA-122 with excellent reproducibility.2. Hyper-Branched Hybridization Chain Reaction for Triggered AmplificationA hyper-branched hybridization chain reaction (HB-HCR) is presented herein, which consists of only six species (two super-hairpins, two hairpins and two assistant DNAs) that can stably coexist until the introduction of initiator DNA to trigger a cascade of hybridization events, leading to the self-sustained assembly of hyber-branched and nicked double-stranded DNA structures. The validity of the reaction and morphologies of the triggered assembly are confirmed by native PAGE analysis and AFM imaging. The system with kinetics can readily achieve ultrasensitive detection of target DNA.