Development Of Biochemically Modified Inactive Retinal Implants For Fixation Testing In Animal Experiments

Abstract

Purpose: : At present, fixation procedures utilising retinal tacks ensure a sufficient connection of the prosthesis onto the retinal surface. However, this procedure turned out to be traumatic during implantation as well as in case of explantation of the implant. As an alternative to this traumatic procedure we performed biochemical modification of the array surface leading to a direct connection to surface signals of the retina.

Methods: : In the first the microstructures of the array were built up on silicium–wafers to be coated by chemical vapor deposition (CVD) polymerisation using amino–paracyclophane to create amino functions at the surface. In a second step biological signals were immobilized onto the surface. For this reason Lamimine peptides were used to gain a sufficient binding to the retinal muller cells. Hexamethylendiisocyanate (HDI) is used as a spacer on the CVD coating whereas the immobilized peptides gain a covalent binding to the isocyanates of the HDI. For the characterization of the surface coating x–ray photoelectrone spectroscopy (XPS) and FT–Infrared (FT–IR) spectroscopy was used.

Results: : Inactive stimulating arrays were built up successfully. FT–IR and XPS show sufficient coating of the array surface as well as a successful placing of the surface signals onto the spacer.

Conclusions: : clinical, functional and histological examinations may prove the feasibility of this method as an alternative to mechanically operated fixations.

Keywords: retinal degenerations: hereditary • receptors • ganglion cells