Fabrication Of Nanoporous Gold Based Glucose Biosensors And Study Of Their Microstructures And Sensing Properties

During the past decade, preparation of dealloyed nanoporous gold (NPG) has been developped very much. Great attentions have been paid on NPG, due to its unique surface morphology, advanced physical and chemical properties and corresponding potential practical application in the fields of catalysis and energy.Nanomaterials based enzymatic electrodes play an importantt role in biosensors, due to their good sensitivity, high accuracy, low detecting limit, strong stability, and capability of fast and online detection in complex systems. Owing to its low relative density, high specific surface area, good electrical conductivity and good biocompatibility, NPG can enhance the enzyme loading with large amount of suitable pores, and the performance of this kind of sensors will be improved accordingly.Herein, we focus on the development of NPG based glucose biosensors. Meanwhile, from the proposed design and characterization, we have studied the effects of both mediators and self-assembled monolayers (SAMs) on the performance of biosensors and also developed a serious of bio-functionalized NPG/conducting polymer hybrid electrodes and NPG supported CuO thin films for glucose biosensing. We have demonstrated that, compared with normal planar polycrystalline gold, NPG displays higher electrochemical activity, which results from the existence of low index single crystal faces and could promote electron transfer greatly. The results are as following:1. Electrochemical behavior of glucose oxidase (GOx) modified NPG electrode We have assembled GOx successfully on NPG via surface chemical reactions to form bio-functionalized NPG in this part. We find that inner-sphere/outer-sphere electron transfer mechanisms of diffusing redox mediators are responsible to the difference of NPG based biosensor performance, which is not completely studied before. 2. Examining effects of SAMs on NPG based amperometric glucose biosensors In this work, we manage to fabricate another group of glucose biosensors by wiring the GOx on NPG surface with different kinds of SAMs. We have demonstrated that the biosensor behavior is sensitive to the SAM layer thickness. Compared with planar polycrystalline gold (polyAu), the re-configuration of NPG in acid solution and reductive desorption of SAMs on NPG display unique features, due to low-index facets of Au(111), Au(100) and Au(110) on NPG, which is not reported before.3. One-step fabrication of bio-functionalized NPG/poly (3,4-ethylenedioxythiophene) hybrid electrodes for amperometric glucose sensingWe employ a new and simple one-step approach to construct a hybrid film by simultaneously electropolymerizing3,4-ethylenedioxythiophene (EDOT) and GOx on NPG. Under the relatively low constant potential of200mV (vs. SCE), the biosensors show selectively response to glucose and display promising sensitivity with a wide linear range.4. Controllable growth of ultrathin copper oxide film on NPG for non-enzymatic glucose determinationWe adopt a simple, time-saving and controllable two-step electrodeposition to construct NPG/CuO nanohybrids for non-enzymatic glucose sensors. We can control the thickness of CuO by tuning the deposition parameters. As the biosensing membrane is around5run, the optimal sensor shows a very high sensitivity with a wide linear range (up to12mM glucose) and good tolerance against interference.