In vitro testing of a protease-sensitive contrast agent for optoacoustic imaging

Anthony H. Green, James R. Norris, Jing Wang, Zhixing Xie, Hao F. Zhang, Patrick J. La Riviere

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

We have designed a protease-sensitive imaging probe for optoacoustic imaging whose absorption spectrum changes upon cleavage by a protease of interest. The probe comprises an active site, a derivative of chlorophyll or natural photosynthetic bacteriochlorophyll that absorbs in the near infrared, conjugated to a peptide backbone specific to the protease being imaged. The uncleaved molecules tend to aggregate in dimers and trimers causing a change in the absorption spectrum relative to that of the monomer. Upon cleavage, the probe molecules de-aggregate giving rise to a spectrum characteristic of monomers. We show using photospectrometry that the two forms of the probe have markedly different absorption spectra, which could allow for in vivo optoacoustic identification using a multiwavelength imaging strategy. Optoacoustic measurements using a narrow-band dye laser find spectral peaks in the two forms of the probe at the expected location. The optoacoustic signal from the uncleaved probe is found to be considerably weaker than that of the cleaved probe, perhaps due to poor optical-acoustic coupling in the aggregated molecules. However, ultimately, it is detection of the cleaved probe that is of the greatest import since it reports on the protease activity of interest.

Original languageEnglish (US)
Title of host publicationPhotons Plus Ultrasound
Subtitle of host publicationImaging and Sensing 2010
DOIs
StatePublished - May 3 2010
EventPhotons Plus Ultrasound: Imaging and Sensing 2010 - San Francisco, CA, United States
Duration: Jan 24 2010Jan 26 2010

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume7564
ISSN (Print)1605-7422

Other

OtherPhotons Plus Ultrasound: Imaging and Sensing 2010
CountryUnited States
CitySan Francisco, CA
Period1/24/101/26/10

Keywords

  • Molecular imaging
  • Optoacoustic imaging
  • Proteases

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Biomaterials
  • Radiology Nuclear Medicine and imaging

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