Drug eluting coating for 3D Parylene sheath electrode

Two methods for incorporating drug eluting coatings consisting of Matrigel (MG) loaded with dexamethasone (DEX) onto the Parylene sheath electrode (PSE) were developed and compared. The purpose of the coatings is to reduce the immune response evoked by tissue damage during electrode insertion into the cortex and subsequent sustained aggravation of tissues by the implant. Parylene surfaces are hydrophobic and repel MG, therefore, both physical and chemical methods were investigated to disrupt surface tension and increase surface energy to facilitate even coating onto the PSE. A gelling step was also investigated to improve loading of coating onto PSE. Spectrophotometry was used to measure the amount of DEX loaded onto the PSE. Loading of up to 563 ng of DEX was achieved by using a combination of surface energy modification and coating gelling, whereas sonication assisted coating methods loaded 205 ng.