| The quality of life and life expectancy of the human population have increased substantially in recent decades. One of the outcomes of increasing age is that some people face diseases that can only be relieved by the use of implantable medical devices (IMDs) (e.g., pacemakers and deep brain neuroestimulators). Therefore, the design of IMDs with new capabilities, preferably avoiding the use of batteries, is highly desirable. These devices should occupy low volume, demand small amounts of energy, and use power sources that can harvest energy in real time from the human body. The use of enzymatic Biofuel Cells (BFCs) arises as a promising technology for this purpose. Although the idea of using BFCs in vivo to produce energy from the human body is a fascinating concept, the use of free enzymes in these devices faces two critical limitations: short enzyme lifetime and low electrical linkage of the enzyme with the electrode. The aim of this dissertation was to develop a method for producing a novel enzymatic nanocomposite (GOx-nanocomposite) with enhanced stability and electrochemical performance. For this purpose, cross-linked glucose oxidase (GOx) aggregates were entrapped within a graphitized mesoporous carbon (GMC) network by utilizing the strong self-aggregation tendency of GMC in aqueous buffer solution to form carbon networks. The effect of the morphology, surface chemistry, and graphitization index of the carbonaceous nanomaterial used as enzyme supports on the performance and stability of the nanocomposites was investigated. Results suggest that the graphitization index and morphology of the carbon nanostructures are critical design parameters for determining the electrochemical performance of the GOx-nanocomposites. Meanwhile, the enzyme loading was dependent on the acid treatment of the carbon nanomaterials. GOx-nanocomposites produced in this work maintained up to 99% of their initial activity after undergoing a thermal shock test conducted at 60°C for four hours. This contrasts to the complete deactivation of the free GOx subjected to the same conditions. The BFCs that use GOx-nanocomposites were able to produce a power density of up to 22.4 muW cm-2 at 0.24V, which is 4.5 times higher than the power density obtained when just GOx-aggregates were used as biocatalysts. |
