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In vivo photoacoustic multi-contrast imaging and detection of protein interactions using a small near-infrared photochromic protein
Author(s): Lei Li; Anton A. Shemetov; Peng Hu; Daria M. Shcherbakova; Junhui Shi; Junjie Yao; Vladislav V. Verkhusha; Lihong V. Wang
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Paper Abstract

Photoacoustic (PA) computed tomography (PACT) is a non-invasive imaging technique offering optical contrast, high resolution, and deep penetration in biological tissues. PACT, highly sensitive to optical absorption by molecules, is inherently suited for molecular imaging using optically absorbing probes. Genetically encoded probes with photochromic behavior dramatically increase detection sensitivity and specificity of PACT through photoswitching and differential imaging. Starting with a DrBphP bacterial phytochrome, we have engineered a near-infrared photochromic probe, DrBphP-PCM, which is superior to the full-length RpBphP1 phytochrome previously used in differential PACT. DrBphP-PCM has a smaller size, better folding, and higher photoswitching contrast. We have also developed an advanced PACT technique, which combines the reversibly-switchable photochromic probes with single-impulse panoramic PACT, termed RS-SIP-PACT. Using RS-SIP-PACT, we have characterized DrBphP-PCM both in vitro and in vivo as an advanced near-infrared photochromic probe for PACT. We introduce two phytochromes into the same mammalian cells, resulting in a distinctive decay characteristic in comparison with the cells expressing DrBphP-PCM only. By discriminating the different decay characteristics, we successfully separate multiple cell types in deep tissues. The simple structural organization of DrBphP-PCM allows engineering a bimolecular PA complementation reporter, a split version of DrBphP-PCM, termed DrSplit. DrSplit enables PA detection of protein-protein interactions in deepseated mouse tumors and livers, achieving 125-μm spatial resolution and 530-cell sensitivity in vivo. The combination of RS-SIP-PACT with DrBphP-PCM and DrSplit holds great potential for non-invasive multi-contrast deep-tissue functional imaging.

Paper Details

Date Published: 27 February 2019
PDF: 6 pages
Proc. SPIE 10878, Photons Plus Ultrasound: Imaging and Sensing 2019, 1087818 (27 February 2019); doi: 10.1117/12.2509198
Show Author Affiliations
Lei Li, Caltech (United States)
Anton A. Shemetov, Albert Einstein College of Medicine (United States)
Peng Hu, Washington Univ. in St. Louis (United States)
Daria M. Shcherbakova, Albert Einstein College of Medicine (United States)
Junhui Shi, Caltech (United States)
Junjie Yao, Duke Univ. (United States)
Vladislav V. Verkhusha, Albert Einstein College of Medicine (United States)
Univ. of Helsinki (Finland)
Lihong V. Wang, Caltech (United States)


Published in SPIE Proceedings Vol. 10878:
Photons Plus Ultrasound: Imaging and Sensing 2019
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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