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Published December 2019 | Supplemental Material + Published
Journal Article Open

Focusing light inside live tissue using reversibly switchable bacterial phytochrome as a genetically encoded photochromic guide star


Focusing light deep by engineering wavefronts toward guide stars inside scattering media has potential biomedical applications in imaging, manipulation, stimulation, and therapy. However, the lack of endogenous guide stars in biological tissue hinders its translations to in vivo applications. Here, we use a reversibly switchable bacterial phytochrome protein as a genetically encoded photochromic guide star (GePGS) in living tissue to tag photons at targeted locations, achieving light focusing inside the tissue by wavefront shaping. As bacterial phytochrome-based GePGS absorbs light differently upon far-red and near-infrared illumination, a large dynamic absorption contrast can be created to tag photons inside tissue. By modulating the GePGS at a distinctive frequency, we suppressed the competition between GePGS and tissue motions and formed tight foci inside mouse tumors in vivo and acute mouse brain tissue, thus improving light delivery efficiency and specificity. Spectral multiplexing of GePGS proteins with different colors is an attractive possibility.

Additional Information

Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited. Submitted 23 May 2019. Accepted 9 October 2019. Published 11 December 2019. We thank J. Ihalainen (University of Jyväskylä, Finland) for the DrBphP gene, M. Monakhov for the isolation of neurons and help with their imaging and H. Ruan for insightful discussions on the work. Funding: This work was supported by NIH grants GM122567 and NS103573 (both to V.V.V.) and EB016986 (NIH Director's Pioneer Award), CA186567 (NIH Director's Transformative Research Award), NS090579, and NS099717 (all to L.V.W.). Author contributions: L.L., J.Y., Y.L., and L.V.W. conceived the study. L.L. and J.Y. designed the experiments. J.Y. constructed the DOPC system. J.Y., L.L., Y.L., Y.S., and J.L. performed the DOPC experiments. A.A.S. and V.V.V. constructed the plasmids, characterized the purified proteins, established the stable cell lines, and prepared the AAVs. L.L. and A.A.S. cultured the mammalian cells. S.L., Y.Z., and Y.O. performed the AAV transfection in vivo and prepared the brain slices. J.Y. and L.L. analyzed the data. L.V.W. supervised the study. J.Y., L.L., A.A.S., V.V.V., and L.V.W. wrote the manuscript. All authors reviewed the manuscript. Competing interests: L.V.W. has a financial interest in Microphotoacoustics Inc., CalPACT LLC, and Union Photoacoustic Technologies Ltd., which, however, did not support this work. The other authors declare no competing financial interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.

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Published - eaay1211.full.pdf

Supplemental Material - aay1211_Movie_S1.mp4

Supplemental Material - aay1211_Movie_S2.mp4

Supplemental Material - aay1211_SM.pdf


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August 19, 2023
October 18, 2023