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Proceedings Paper

Photoacoustic and fluorescent imaging GAF2 photoswitchable chromoproteins (Conference Presentation)
Author(s): Ryan K. Chee; Yan Li; Robert J. Paproski; Robert E. Campbell; Roger J. Zemp

Paper Abstract

Molecular photoacoustic imaging is hindered by hemoglobin background signal. Photoswitchable chromoproteins can be used to obtain images with significantly reduced background signal. Molecular imaging of multiple biological processes via multiple chromoprotiens is difficult due to overlapping imaging spectra. Using a new rate-of-change imaging methodology, we can obtain molecular images with multiple chromoprotiens with overlapping imaging spectra. We also present a new photoswitchable chromoprotein, GAF2, which is significantly smaller than the BphP1 which has shown promise for photoswitchable photoacoustic imaging [Yao et al., Nat. Meth. 13, 67–73 (2016)]. We use BphP1 and GAF2 with photoacoustic (Vevo LAZR, Fujifilm Visualsonics Inc) and fluorescence (In vivo Xtreme, Bruker) imaging systems to show background-free multiplexed images. We image before, after, and during photoconversion to obtain background-free rate-of-change images and compare our results to difference imaging and spectral demixing. After phantom imaging, we inject mice with different chromoprotein-expressing E. coli bacteria to show multiplexed images of bacterial infections. We show distinguishable differences in the rate-of-change between GAF2 and BphP1. We obtain rate-of-change feasibility images and in vivo images in mice showing the ability to differentiate between GAF2 and BphP1 even though they are spectrally similar. We photoconvert both GAF2 and BphP1 using 550nm and 735nm light. Phantom studies suggest a 10-20dB improvement in the rate-of-change and difference images in comparison to images with background. Multiplexed background-free molecular imaging using chromoproteins could prove to be a promising new imaging methodology especially when combined with spectral demixing.

Paper Details

Date Published: 24 April 2017
PDF: 1 pages
Proc. SPIE 10064, Photons Plus Ultrasound: Imaging and Sensing 2017, 100642A (24 April 2017); doi: 10.1117/12.2250225
Show Author Affiliations
Ryan K. Chee, Univ. of Alberta (Canada)
Yan Li, Univ. of Alberta (Canada)
Robert J. Paproski, Univ. of Alberta (Canada)
Robert E. Campbell, Univ. of Alberta (Canada)
Roger J. Zemp, Univ. of Alberta (Canada)


Published in SPIE Proceedings Vol. 10064:
Photons Plus Ultrasound: Imaging and Sensing 2017
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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