Photodynamic therapy by nonresonant two-photon excitation

Karsten Koenig; Iris Riemann; Peter Fischer

doi:10.1117/12.351512

6 July 1999 Photodynamic therapy by nonresonant two-photon excitation

Karsten Koenig, Iris Riemann, Peter Fischer

Proceedings Volume 3592, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy VIII; (1999) https://doi.org/10.1117/12.351512
Event: BiOS '99 International Biomedical Optics Symposium, 1999, San Jose, CA, United States

Abstract

Intracellular photodynamic reactions by nonlinear excitation of porphyrin photosensitizers have been induced using near infrared ultrashort laser pulses at 200 fs pulse width, 80 MHz pulse repetition rate and 2 mW mean laser power. In particular, a highly focused 780 nm pulsed laser scanning beam was employed at a frame rate of 1/16 s^-1 (60 microsecond(s) pixel dwell time) to expose Photofrin-labeled and aminolevulinic acid (ALA)-labeled Chinese hamster ovary cells. Intracellular accumulation and photobleaching of the fluorescent photosensitizers protoporphyrin IX and Photofrin have been studied by non-resonant two-photon fluorescence excitation. Subsequent scanning of the sensitizer-labeled cells resulted in reduced cloning efficiency of 50% and 0% after about 13 scans (approximately equals 10 mJ) and 50 scans, respectively, in the case of Photofrin accumulation (5 (mu) g/ml) and after about 24 scans and 100 scans in the case of ALA administration (1.5 mg/ml). Live/dead assays revealed the loss of vitality of most of cells after 50 scans for Photofrin-labeled cells and 100 scans for ALA-labeled cells. Sensitizer-free control cells could be scanned more than 250 times (1.1 h) without impact on the reproduction behavior, morphology, and vitality.

Citation Download Citation

Karsten Koenig, Iris Riemann, and Peter Fischer "Photodynamic therapy by nonresonant two-photon excitation", Proc. SPIE 3592, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy VIII, (6 July 1999); https://doi.org/10.1117/12.351512

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