Graphene Based On Surface Plasmon Resonance Biosensor And Applications

Surface plasmon resonance (SPR) sensors are sensitive optical techniques formonitoring refractive index changes on a sensor surface, which are applied in physics,chemistry, biology, medicine, environment fields. With development ofnano-materials, many novel phenomena are discovered in SPR, which are formed ahot topic–Plasmonic. Not only many new phenomena and new problems are found,but also great potential application are attended, which has become one of the hottestareas in all over the world. Since graphene was obtained using a mechanicalexfoliation method in2004, extensive interest has been attracted to explore itsexciting applications in various fields, such as high-performance nano-electronicdevices, electrochemical catalysis, energy storage. As a precursor of grephene, themechanism and application of interaction between GO and molecular, doping effectsand detection oxidation state are significant in scientific and technical aspects, whichcan promote nanotechnology applications in materials, information, energy, biology,medicine and optic fields.Research on cross graphene-based materials with SPR has many unresolvedissues that we need to explore, this paper will combine the advantages ofgraphene-based materials with SPR instrument, carried out the following research:1. We assemble a graphene oxide film on SPR chip surface and then convert itinto reduced graphene by an in-situ electrochemical method. The mechanism andapplication of SERS from graphene-based substrates are investigated. The average thickness and dielectric constant of GO are varied significantly with the switch of itsoxidation state. Electrochemical reduction decreases the distance between carbonatoms and gold surface by removing the spacer of oxygen functional groups. Theelectromagnetic field of graphene surface is therefore enhanced and resulting in anenhancement of Raman signal. A p-doping of electrochemical reduced GO ERGOthrough the interaction between Au and ERGO is also observed.2. We report the use of surface plasmon resonance for direct sensing ofDNA/GO binding, which can be used for ultra-sensitive detection of single-strandedDNA (ssDNA). Furthermore, the results confirm that hydrogen bonding plays a keyrole in the interaction between GO and ssDNA. This enables to a novel biosensor forhighly sensitive and selective detection of ssDNA based on indirect competitiveinhibition assay (ICIA). We report development of such a sensor with a lineardynamic range of10-14-10-6M, a detection limit of10fM and a high level ofstability during repeated regeneration.3. We put forward a novel strategy to realize controllable energy bandengineering in defect-rich graphene. The existence of rich defects in the grapheneresults to lots of dangling bonds, which is benefited to bind with R6G molecule as acovalent bond. The defect-rich graphene can also be used to sensitive layer forsensing R6G molecule on SPR sensor. The limit of detection is of10-17M (0.01fM)down to a single molecular level. The concept of a designer-made biosensor with anenhancing functionality, a defect-rich graphene with controlled molecule doping, andoptical-tunable properties offers numerous opportunities in the development of newbiological and chemical sensor and sensing strategies.4. A new method is used to detect metal ions on SPR sensor chip. GO wasassembled on the SPR chip surface to detect Fe3+, Cu2+, Pb2+, and Sn4+. The GO canbe used to detect Fe3+with a linear dynamic range of10-14-10-8M, a detection limitof10fM. The results show that the GO-based SPR sensor to detect iron ion withselective and ultra-low detection limit.