Noble Metal Nanomaterials Based Biosensor And Their Applications

Biosensors with high performance are highly pursued in order to meet the growing demands and challenges in a large number of analytic applications such as environmental monitoring, food safety control,medical diagnosis, or even military defense. Noble metal nanomaterials (NMNMs) with special size-dependent chemical and physical properties show superior advantages and bring new concepts for biosensor construction. Over the past decade, researchers have devoted considerable attention to the integration of a biosensor with NMNMs to yield high performance bioelectronic devices. This thesis focuses on exploring new ultrasensitive NMNMs-based biosensors starts from the relationship between the sensitivity and the structure features.1) Fractal gold modified electrode for ultrasensitive thrombin detectionA fractal gold modified electrode (FracAu) was prepared by electrodeposition and exhibited a highly branched tree-like structure with the thickness of 10 um and the small side branch of 90 nm. By using a thiol-modified aptamer as thrombin probe and hydroxymethyl ferrocene as the electroactive signal probe, the as-prepared biosensor exhibited a detection limit of 5.7 fM and show great promise for clinical diagnosis.2) Space-confined fabrication of silver nanodendrites and their enhanced SERS activityA simple, controllable, reproducible and universal approach for constructing noble metal nanodendrites (Ag NDs, Au NDs, Pt NDs) on a microwell patterned ITO electrode. Without adding any other additives, nanostructures could be tuned from boulders to dendrites by varying the size of the microwell and the electrodeposition time. The prepared Ag NDs were employed as a SERS substrate for R6G detecting and exhibit excellent SERS enhancement. Our approach for fabricating nanodendrites provides a new strategy for fabricating noble metal NDs, which have promising applications in catalysis, electronics and sensing3) Self-interconnecting Pt nanowire network electrode for electrochemical amperometric detecting of hydrogen peroxide and glucoseA self-interconnecting Pt nanowire network electrode (PtNNE) for detection of hydrogen peroxide and glucose with ultrahigh sensitivity and stability was prepared. PtNNE has a very large electrochemcial active surface area and consists of polycrystalline nanowires with high-index facets. PtNNE showed an extremely high sensitivity of 1360 μA·mM-1·cm-2 towards H2O2. PtNNE was also applied to fabricate the GOx-based glucose biosensor. As a result, it showed a detection limit of 1.5 μm towards glucose, an ultrahigh sensitivity as high as 114 μA mM-1 cm-2, and also great detection range from 5 μM to 30 mM.