Biocompatible retinal prosthesis based on a conjugated polymer photoactive layer

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 DESCRIPTION (provided by applicant): This proposal is in response to a specific, approved topic area as defined by the NEI in Appendix A: National Institutes of Health SBA-Approved SBIR/STTR Topics for Awards over Statutory Budget Limitations from the PHS 2014-2 Omnibus Solicitation for SBIR/STTR Grant Applications. This Phase I feasibility study is an advanced technology project with a clearly identified product that will result in a clinically relevant treatment for retinal disease. The award period and amount requested are guided by project needs and are in compliance with issued guidelines. Age-related macular degeneration and retinitis pigmentosa are cause millions of cases of blindness due to retinal degradation. Treatment options such as transplants, vitamin supplements, or pharmaceuticals are available, but they may only serve to slow the disease or be of limited efficacy. New treatment options such as gene or stem cell therapy are of only limited value due to technical difficulties or questionable safety. Prosthetic options are promising and are undergoing clinical evaluation. There are several drawbacks with current prosthetic models including limited resolution, excessive external hardware, and biocompatibility problems in part due to excessive heat or current generation. Conjugated polymers, however, have been shown to produce a spatially localized response from explanted retinas using only illumination as a power source. The advantages over previously established retinal prosthetics include little to no heat generation, improved biocompatibility, and no need for external hardware or a multi-electrode array. For better biocompatibility and overall functionality, we propose the development of alternative photoactive materials that are better suited to the eye's own biology. We propose to develop prosthetics consisting of a hydrogel substrate coated with an active layer of conjugated polymer block copolymer. These materials are improvements upon the current research in conjugated polymers for retinal activation in that they are all-soft materials that enable the diffusion of nutrients through a gel. Our specific aims are designed to demonstrate feasibility, in vitro biocompatibility, stability, and ability to activate retinal neurons in explanted rat retinas. Thes aims include: 1) the formulation of conjugated polymer/hydrogel prostheses, 2) determine in vitro biocompatibility and photochemical stability, and 3) demonstrate prosthesis operation ex vivo with explanted photoreceptor degenerate rat retinas. Successful completion of these aims will yield suitable candidates to be used in a retinal prosthesis. We will characterize polymers fo their photoelectrochemical activity and ability to diffuse nutrients. We will also assess in vitro biocompatibility and stability by evaluating the viability and histology of cells cultured on our materials under illumination as they would be in operation. We will assess their ability to stimulate explanted animal retinas by evaluating activity threshold, range, frequency, and spatial localization. A revision of form factor such as this could precipitate a paradigm shift in the approach taken to develop prosthetic technologies as well as push boundaries in light-activated neural interfaces.