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Imaging Novel Ruthenium bipyridine-based Nanophotoswitches in Retina

Yue, Lan and Walston, Sean and Lin, Mingyi S. and Pribisko, Melanie and Dougherty, Dennis and Grubbs, R. and Gray, Harry and Chow, Robert and Humayun, Mark S. (2015) Imaging Novel Ruthenium bipyridine-based Nanophotoswitches in Retina. Investigative ophthalmology & visual science, 56 (7). p. 1676. ISSN 0146-0404.

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Nanophotoswitches (NPSs) offer a new tool for optical stimulation of neuronal activity, in vitro and also potentially in vivo. Our group previously reported a ruthenium bipyridine (Rubpy)-based NPS that inserts into the plasma membrane and upon visible illumination generates an electrical dipole, triggering action potentials in adrenal chromaffin cells. We have recently demonstrated that after intravitreal injection of this NPS into the eyes of blind rats, illumination of the eye elicited electrical activity in the contralateral superior colliculus. To better understand the site of action of the NPS in retina, we examined the distribution of the molecules in different retinal layers after intravitreal injection. Methods: Rubpy molecules can be visualized by their luminescence (610 nm) upon visible wavelength illumination (460 nm). To resolve the luminescence from different retinal layers, a rapid-scan twophoton imaging system (LaVison) was used (Ti:Sapphire laser tuned to 900 nm). Intravitreal injection (1 mM, 4 μL Rubpy-based NPSs in BSS), followed by eye removal and retina isolation 2-5 hrs after, was performed on young RCS rats. Luminescence images of the wholemount retina were captured by an EM-CCD camera (Andor). Results: At 2 hrs after intravitreal injection and with continuous superfusion of Ames medium, luminescence was confined near the injection site. Luminescence was observed localized to surface membranes of axons and somata of retinal ganglion cells (RGC), demonstrating the impermeability of the cell membrane to the NPS molecules. The outer retina did not show significant luminescence. After 3 additional hours, luminescence was more diffused within the RGC layer and still did not extend to the outer retina. Conclusions: This study shows marked staining of RGC layer by intravitreally injected Rubpy-based NPS molecules, consistent with the hypothesis that the photoactivated NPS molecules induce electrical activity in the superior colliculus by acting on the RGCs that deliver electrical signals to the visual pathway outside the eyes. Distinct from other nano-scale optical cellular modulating approaches using optogenetics or azobenzene-based photoswitches, the NPS approach obviates the need for gene manipulation or toxic UV illumination, highlighting its potential in generating high-acuity prosthetic vision in patients blinded by retinal degenerative diseases.

Item Type:Article
Related URLs:
URLURL TypeDescription
Dougherty, Dennis0000-0003-1464-2461
Grubbs, R.0000-0002-0057-7817
Gray, Harry0000-0002-7937-7876
Humayun, Mark S.0000-0002-5830-5208
Additional Information:© 2015 by the Association for Research in Vision and Ophthalmology, Inc. NSF CBET-1404089; Research to Prevent Blindness; USC Eye Institute; Institute of Biomedical Therapeutics.
Funding AgencyGrant Number
Research to Prevent BlindnessUNSPECIFIED
Institute of Biomedical TherapeuticsUNSPECIFIED
Issue or Number:7
Record Number:CaltechAUTHORS:20151113-113545991
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:62097
Deposited By: Ruth Sustaita
Deposited On:18 Nov 2015 00:40
Last Modified:09 Mar 2020 13:18

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