Generating Electricity within the Physiological Environment for Low Power Implantable Medical Device Applications: Towards the development of in-vivo biofuel cell technologies

摘要

Electrochemical studies were performed to explore electron transfer (ET) between human white blood cells (WBC) and carbon fiber electrodes (CFE). Currently, an active area of research involves encouraging ET between microbes and various electrodes in a biofuel cell (BFC). ET between microbes and electrodes are thought to occur i) directly through plasma membrane-bound electron transport chain proteins; and/or ii) indirectly through the release of metabolic products or biomolecules near the electrode surface. An important motivation of this research is the need for alternative long lasting power sources for implantable diagnostic and therapeutic devices. A particular interest is reducing the size and weight of implantable devices. Currently employed internal batteries largely contribute to both. BFCs are promising prospects as they couple the oxidation of a biofuel (such as glucose) to the reduction of molecular oxygen to water. Both glucose and oxygen are abundantly present within our body's cells and tissues. The goal of this project is to explore the feasibility of utilizing WBCs (a human cell model) to generate electricity by fostering direct or indirect ET between these cells - or more specifically, between the metabolic processes of these cells - and the anode of a BFC. ET from the metabolic processes of whole cells to electrodes had, to the best of our knowledge, only previously been demonstrated for microbes. The electrochemical activities of WBCs isolated from whole human blood by red blood cell (RBC) lysis, peripheral blood mononuclear cells (PBMCs) isolated on a Ficoll-Paque gradient, as well as cells from a BLCL cell line and two leukemia cell lines (K562 and Jurkat) were all investigated by incorporation of the cells into the anode compartment of a proton exchange membrane fuel cell (PEMFC). Cyclic voltammetry was employed as an electrochemical technique to investigate the ET ability of the cells, as it can reveal both thermodynamic and kinetic information regarding oxidation-reduction processes at the CFE surface. The results of our studies demonstrate that upon activation, biochemical species, such as serotonin, are released by PBMCs, which may become irreversibly oxidized at the electrode surface.