DEVELOPMENT OF BIOCELLULOSE-FIBROIN CONDUCTIVE SUBSTRATES FOR RETINAL IMPLANTS APPLICATIONS

Abstract

Legal blindness is defined by the World Health Organization as a condition of visual acuity less than 20/400 or a visual field of less than 20° in the best-vision eye. According to this definition, in 2010 there were 39 million blind patients worldwide. Retinitis pigmentosa (RP) is the most common cause of hereditary blindness, affecting about 1.5 million people. In this disease, photoreceptor cells gradually lose their function, leading to a progressive reduction in visual and field acuity from the periphery. There is no cure for RP, but several treatments are being tested. Implants capable of replacing photoreceptors and to excite retinal output neurons can, in principle, restore visual perception.This project aims to develop a route to obtain flexible semiconductor substrates, based on bacterial cellulose (BC) and fibroin, aiming at the manufacture of optoelectronic devices to act as photodetectors in retinal implants. To this end, the growth of metal-organic microcrystalline structures derived from TCNQ (7,7,8,8-tetracyanoquinodimethane) of the M+TCNQ- type and organic co-crystals of the TCNQ-donor type (donor = pyrene; perylene ). TCNQ is known in the literature as a versatile molecular semiconductor, acting as a suitable electron acceptor in the formation of charge transfer complexes (CT) when in contact with donor groups. Considering the biological application, we intend to evaluate the cytotoxicity of the materials used by means of cytotoxicity assays against rapidly proliferating cell cultures MRC-5 (lung fibroblast) and U87 (human glioblastoma). To obtain the CT films, the spin-coating technique will be used, as well as the combination of physical vapor deposition methods and chemical displacement reactions in the solid state. Next, the influence of the CT layer on the mobility of charge carriers will be investigated from the construction of BC/ITO/CT/Al type devices, as well as the physical and optical characteristics of the devices.