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A synthetic, soft tissue retina was just developed by an Oxford University student that could offer fresh hope for degenerative eye conditions such as retinitis pigmentosa.
Until now, all artificial retinal research has used rigid, hard materials only. The new research, by Vanessa Restrepo-Schild, a 24 year old PhD student and researcher at the Oxford University, Department of Chemistry, is the first to successfully use biological, synthetic tissues, developed in a laboratory environment. Her study could revolutionise the bionic implant industry and development of new, less invasive technologies that closely resemble human body tissues.
Just as photography depends on how camera pixels react to light, our eyesight relies on how our retina cells (made up of proteins) convert signals into electrical pulses. Real retinal cells transmit those pulsess to nerves in our brain, ultimately building a picture of the scene being viewed.
The team developed a new synthetic, double layered retina which closely mimics the natural human retinal process. It consists of soft water droplets (hydrogels) and biological cell membrane proteins. Designed like a camera, the cells act like pixels, detecting and reacting to light, in order to create a grey scale image in neurons of our brains.
The study, published in the journal Scientific Reports, shows how unlike existing artificial retinal implants, these cell-cultures are created from natural, biodegradable materials that do not contain foreign bodies or living tissues. The implant is less invasive than a mechanical device, so less likely to create an adverse reaction.
Although at present the synthetic retina has only been tested under laboratory conditions, Restrepo-Schild wants to explore its potential with living tissue. This next step is vital in knowing how her new material performs as a bionic implant.
Restrepo-Schild has filed a patent for the technology. The next phase of her work will see the Oxford team expand the retina's function to include recognising different colors.
Notes to editors: The full paper 'Light-Patterned Current Generation in a Droplet Bilayer Array' By Vanessa Restrepo Schild, Michael J. Booth, Stuart J. Box, Sam N. Olof, Kozhinjampara R. Mahendran and Hagan Bayley is available to download from the journal Scientific Reports.
(a) Schematic of a light-activatable droplet hydrogel bilayer (DHB) bio-pixel. In a lipid-in-oil
solution, a bR-containing droplet (purple) forms a bilayer with a hydrogel cube (blue).
(b) Image of a bio-pixel within the droplet. The bR proteins inserted into the bilayer pump protons
across the membrane when illuminated with GREEN LIGHT (as shown in (a)).The current
moving across the membrane is measured with Ag/AgCl electrodes inserted into both droplet
(c) Ionic current activativated only upon illumination. Purple box indicates a steady-state current.
(d) All points histogram of the steady-state current from (c). A bio-pixel was considered ON when
the steady-state current was above a 1 pA cutoff (vertical dashed green line). Scale bar 1.5 mm.
Image Credit: Vanessa Restrepo-Schild/Oxford University