Graphene Derivatived Materials For The Construction Of High-performing Electrochemical Biosensor

Graphenes and graphene-based nanocomposites have attracted widely attentions onthe account of the enhancedchemicophysical properties of graphene (e.g. highsurface-to-volume ratio, excellent conductivity and biocompatibility) and novelfunctionalities of the modified material or biomolecules (e.g. function nanomaterials,biomaterials and polymers).Graphene-based nanomatericalswere used as promisingplatform and materials to amplify the detection signals and increase the substractareas for fabricating high performance electrochemical biosensors according to itsversatility and modification. In present work, we fabricated severalfunctionalizedgraphene-based nanocomposites via simply and noncovalent modification to exploretheir applications in the field of high performance electrochemical biosensor. Themain points of the thesis were outlined as follow:1. Mimetic biomembrane coated gold nanoparticles (DMPG-AuNP) modified onchemically reduced graphene sheets was utilized as a host matrix for enzymeimmobilization. Owing to the biocompatible microenvironment provided by themimetic biomembrane, microperoxidase-11entrapped in this matrix retained itsnative structure and exhibited high bioactivity. The as-prepared third-generationbiosensor presented high electrocatalytic activity, good stability and reproducibilityfor H2O2detection. Furthermore, we demonstrated that the biosensor could besuccessfully used for the real-time detection of the trace amount of H2O2released bythe cancer cells MCF-7in response to a pro-inflammatory stimulant.2. A highly performance three-dimensional (3D) electrochemical immunosensor wasdeveloped for sensitive detection of the tumor biomarker, carcinoembryonic antigen (CEA). Immuno-recognition interface was fabricated via simple and non-covalentimmobilization of antibody though the lectin-mediated interactions betweenconcanavalin A and horseradish peroxidase-labeled antibody. The3D immunosensoris able to detect CEA in a short incubation time (30min)with the wide linear range(0.1-750.0ng/mL) and low detection limit (90pg/mL at a signal-to-noise ratio of3).Furthermore, this biosensor was used for the detection of CEA level in real serumsamples.3. A cytosensor was constructed with ferronece-appended poly(allylaminehydrochloride) functionalized graphene (Fc-PAH-G),poly(sodium-p-styrenesulfonate)(PSS) and aptamer (AS1411) by layer-by-layerassembly technology for detection of cancer cells.Fc-PAH-G brings probes and alsopromotes electron transfer on the electrode. LBL technology provided more effectiveprobes to enhance amplified signal for improving the sensitivity of the detection. Thecytosensor exhibited good stability, selectivity and high sensitivity for the detection ofHela cells. And, a widedetection range from10to106cells/mL with a detection limitas low as10cells/mL was obtained.