Surface modifications of metallic electrodes for the reduction of inflammatory response after implantation
(2012)
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- Authors
- Supervisors
- Demoustier-Champagne, Sophie
- Abstract
- (en) Nerve implanted prostheses are of great interest for the recovery of damaged neurological functions by the electrical stimulation of the peripheral or central nervous system. The small size of the stimulation electrodes requires optimized electrical properties for sufficient recording/stimulating ability. This involves a close and long-lasting contact between the stimulation electrode and the biological tissues, weakened by the inflammatory reaction occuring after implantation. Improving this contact is one of the main challenges that must be faced in the development of long-term active implantable stimulators. Surface modifications of the materials intended for implantation are one of the keys evoked to control and improve the occurrence of the reactions to implantation, and reconcile both sides of the nerve/electrode interface. In this thesis, we explore three types of surface modifications to address interfacial issues of stimulation electrodes. First, the physical (or structural) modification of the stimulation surface itself is performed through the creation of a model nano-structuration on the metallic surface, by a brush of self-standing metallic pillars of nanometric dimensions. The structures are observed and characterized, and the electrical properties of nano-featured electrodes are shown to be improved. Moreover, this model nanotopography is shown to have peculiar effects on cells adhesion, morphology and growth. In the second chapter, we present the development of a method allowing the easy and reproducible fabrication of switchable conducting polymer-coated electrodes (polypyrrole) for the local and electrically-controlled delivery of anti-inflammatory dexamethasone molecules. Two techniques are investigated for the liberation of molecules and optimized for the control on the quantity liberated and the properties of the films, cyclic voltammetry and biphasic pulse potential pulses stimulation. Moreover, the development of a new device for the in-vivo stimulation of polypyrrole-coated metallic electrodes by biphasic potential pulses with determined parameters is evoked, and the first in-vivo experiments carried out. Finally, we present a fabrication process of polypyrrole copolymeric films with specific chemical groups allowing further modifications. We demonstrate that the composition of the copolymer films based on modified pyrrole units can be tailored by playing on different independent electrosynthesis parameters. We also prove the possibility to synthesize multilayer polypyrrole structures for the simultaneous controlled delivery of molecules and grafting of biologically active groups at the surface of the outer layer.
- Affiliations
Citations
Leprince, L. (2012). Surface modifications of metallic electrodes for the reduction of inflammatory response after implantation. https://hdl.handle.net/2078.5/161280