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1 June 2004 Nanophotonic ensembles for targeted multi-photon photodynamic therapy
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There has been a dramatic increase in the application of new technologies for the treatment of cancerous tumors over the past decade, but for the most part, the treatment of most tumors still involves some combination of invasive surgery, chemotherapy and radiation treatments. Photodynamic therapy (PDT), which involves the activation of an administered compound with laser light followed by a series of events leading to programmed cell death of the tumor, has been proposed as a noninvasive alternative treatment to replace the standard surgery/chemotherapy/radiation protocol. However, currently approved PDT agents operate in the Visible portion of the spectrum, and laser light in this region cannot penetrate the skin more than a few millimeters. Two-photon irradiation using more highly penetrating Near-infrared (NIR) light in the tissue transparency window (700-1000 nm) has been proposed for the treatment of subcutaneous tumors, but most porphyrins exhibit extremely small two-photon cross-sections. Classical PDT also suffers from the lengthy time necessary for accumulation at the tumor site, a relative lack of discrimination between healthy and diseased tissue, particularly at the tumor margins, and difficulty in clearing from the system in a reasonable amount of time. We have recently discovered a new design paradigm for porphyrins with greatly enhanced two-photon cross-sections, and are now proposing a nano-ensemble that would also incorporate small molecule targeting agents, and possibly one-photon NIR imaging agents along with these porphyrins in one therapeutic agent. Thus these ensembles would incorporate targeting/imaging/PDT functions in one therapeutic agent, and hold the promise of single-session outpatient treatment of a large variety of subcutaneous tumors.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Charles W. Spangler, Fanqing Meng, Aijun Gong, Mikhail A. Drobizhev, Aliaksandr Karotki, and Aleksander Rebane II "Nanophotonic ensembles for targeted multi-photon photodynamic therapy", Proc. SPIE 5331, Nanobiophotonics and Biomedical Applications, (1 June 2004);

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