Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2011 Apr 15;2(5):1233-42.
doi: 10.1364/BOE.2.001233.

Dual-channel imaging system for singlet oxygen and photosensitizer for PDT

Seonkyung Lee, Martin E Isabelle, Kristin L Gabally-Kinney, Brian W Pogue, Steven J Davis

Dual-channel imaging system for singlet oxygen and photosensitizer for PDT

Seonkyung Lee et al. Biomed Opt Express. .

Abstract

A two-channel optical system has been developed to provide spatially resolved simultaneous imaging of singlet molecular oxygen ((1)O(2)) phosphorescence and photosensitizer (PS) fluorescence produced by the photodynamic process. The current imaging system uses a spectral discrimination method to differentiate the weak (1)O(2) phosphorescence that peaks near 1.27 μm from PS fluorescence that also occurs in this spectral region. The detection limit of (1)O(2) emission was determined at a concentration of 500 nM benzoporphyrin derivative monoacid (BPD) in tissue-like phantoms, and these signals observed were proportional to the PS fluorescence. Preliminary in vivo images with tumor laden mice indicate that it is possible to obtain simultaneous images of (1)O(2) and PS tissue distribution.

Keywords: (170.0110) Imaging systems; (170.3880) Medical and biological imaging; (170.5180) Photodynamic therapy.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
Singlet oxygen 2D imaging system. (a) The schematic of current 2D imaging system (in vivo). (b) Experimental setup of deoxygenating configuration (in vitro).
Fig. 2
Fig. 2
Singlet oxygen detection method. (a) Temporal profiles (using PMT detector) of 1O2 phosphorescence at three bandpass filter positions with 1 μM BPD in methanol. The signal during excitation light ON period (6-11 μs) is due primarily to PS fluorescence with 1320 and 1220 nm filter; or 1O2 emission and PS fluorescence with 1270 nm filter. The increase in the signal with 1270 nm filter is due to increasing 1O2 production during the excitation pulse. (b) Spectral features of 1O2 phosphorescence and total emission intensity with 1 μM BPD in methanol. (c) The method of the 1O2 image process with the three-filter operation (in vitro).
Fig. 3
Fig. 3
Image resolution of the dual-channel system. (a) Visible image. (b) NIR image.
Fig. 4
Fig. 4
Spatially resolved images (10 μM BPD in methanol). (a) Ambient air saturated. (b) Deoxygenated solutions (nitrogen gas purging through the solution). (c) Total BPD fluorescence and singlet O2 phosphorescence intensities in the area of the interest marked with a square box in the images of 5 × 5 mm.
Fig. 5
Fig. 5
Plot of singlet O2 phosphorescence and BPD fluorescence as a function of BPD concentration in 5% FBS with 5% TTX-100. Note that the intensities of PS fluorescence and singlet O2 phosphorescence are not normalized with respect to the signal accumulation conditions of the different camera settings.
Fig. 6
Fig. 6
Images of the BPD fluorescence and singlet oxygen phosphorescence from two tumor laden mice. (a) 1.0 mg BPD / body kg. (b) 0.5 mg BPD / body kg.
See this image and copyright information in PMC

References

    1. Weishaupt K. R., Gomer C. J., Dougherty T. J., “Identification of singlet oxygen as the cytotoxic agent in photoinactivation of a murine tumor,” Cancer Res. 36(7 PT 1), 2326–2329 (1976). - PubMed
    1. Kubler A. C., “Photodynamic Therapy,” Med. Laser Appl. 20(1), 37–45 (2005).10.1016/j.mla.2005.02.001 - DOI
    1. Farrell T. J., Hawkes R. P., Patterson M. S., Wilson B. C., “Modeling of photosensitizer fluorescence emission and photobleaching for photodynamic therapy dosimetry,” Appl. Opt. 37(31), 7168–7183 (1998).10.1364/AO.37.007168 - DOI - PubMed
    1. S. L. Jacques, “Simple theory, measurements, and rules of thumb for dosimetry during photodynamic therapy,” Proc. SPIE 1065, 100–108 (1989).
    1. B. W. Pogue, R. D. Braun, J. L. Lanzen, C. Erikson, and M. W. Dewhirst, “Oxygen microelectrode measurements in R3230Ac Tumors during photodynamic therapy with verteporfin,” Proc. SPIE 4248, 144 (2001).

LinkOut - more resources