Abstract
A femtosecond laser delivering pulses of wavelength 800 nm and 124 fs duration at rates of 1 kHz has been used to investigate the two-photon excited fluorescence in the photosensitizer m-THPC. The scaling of fluorescence amplitude with laser power and fluorescence sidelight imaging are found to support a predominantly two-photon excitation mechanism. A value for the two-photon cross-section of delta = 1.8 x 10-(57) m(4) s is derived by comparing the fluorescence signals excited by wavelengths of 800 and 400nm. Preliminary results demonstrating the two-photon induced PDT activity of m-THPC in an epithelial cell line are also reported. (C) 2006 Elsevier B.V. All rights reserved.