Electrodes and Electrokinetic Systems for Biotechnological Applications

Sammanfattning: Research in bioelectronics studies biological systems and materials in combination with electronic interfaces for the development of devices, e.g., for medical applications, drug and toxicity tests, and biotechnology in general. Neural implants and pacemakers are examples of products developed from this area of research. Conducting polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) bridge biology and electronics with a combination of biocompatibility, flexibility, and capability to themselves undergo redox reactions. Electrokinetics, a related branch of science, describes the motion of fluids and particles caused by the application of an electric field, and includes various separation techniques such as gel electrophoresis. Applying an electric field in a sufficiently small diameter silica capillary can cause the liquid in the capillary to move. This phenomenon, referred to as electroosmosis, plays an important role in miniaturized microfluidic systems and can be used to drive flow in a so-called electroosmotic pump.This thesis describes research at the interface between biology, chemistry and electronics. The first two papers probe the adsorption mechanism of poly-L-lysine, often used in biotechnological applications, onto hard materials such as metals (platinum) and metal oxides (indium tin oxide). By employing a gravimetric technique, quartz crystal microgravimetry with dissipation monitoring (QCM-D) combined with electrochemistry, we studied the process by which poly-L-lysine is deposited onto two different conducting substrates under anodic conditions. We found that indium tin oxide is more suitable than platinum for anodic electrodeposition of PLL, however, the exact film deposition mechanism is not fully understood. Paper 3 demonstrates the applicability of using conducting polymers, (e.g., PEDOT) instead of platinum as electrode material in gel electrophoresis. The last paper describes the fabrication and characterization of an electroosmotic pump consisting of a potassium silicate stationary phase in a fused silica capillary and the integration of the pump into a system for use, e.g., as a bioreactor.