Selective photothermotherapy and spectroscopy of spectrally and spatially heterogenous biological targets with ultrafast laser pulses

Richard C. Straight

doi:10.1117/12.2322300

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1 February 1992 Selective photothermotherapy and spectroscopy of spectrally and spatially heterogenous biological targets with ultrafast laser pulses

Richard C. Straight

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Proceedings Volume 1599, Recent Advances in the Uses of Light in Physics, Chemistry, Engineering, and Medicine; (1992) https://doi.org/10.1117/12.2322300
Event: Recent Advances in the Uses of Light in Physics, Chemistry, Engineering, and Medicine, 1991, New York, NY, United States

Abstract

Locally absorbing microvolumes (10Å-10?m) much smaller than the radiation wavelength in size are characteristic of heterogeneous microstructure in cells and living systems and can be studied and controlled with ultrafast pulses of light. The ultrafast transient absorption and heating of local microvolumes absorbing through endogenous of exogenous chromophores at the radiation wavelength can be used to study size, structure and function of locally overheated microstructures. Pulse-heated microvolumes with altered refractive index and scattering and altered fluorescence are probed with a second light pulse. Also, the pulsed heating of the desired kind of microvolumes in cells and tissues with ultrafast laser pulses of a certain wavelength pulse duration and intensity opens up new possibilities for photothermotherapy. Ultrafast transient overheating of microvolumes may be substantial (?T=1-100 deg) while the time-and space-averaged heating of irradiated macrovolume is much lower. The fast transient perturbation of living systems with ultrafast, tunable laser pulses that significantly effect biological processes form the basis for new therapeutic applications. Ultrashort laser pulses (fs-ns) are shorter in duration than the time it takes for heat to diffuse from microregions even as small as 10-IOOA° across and coupled with their wide-band tunability make it possible to investigate local absorption microregions using endogenous or exogenous chromophores to determine optimum wavelength for spectroscopy and phototherapy. We have demonstrated remarkable effects on cell growth with femtosecond laser pulses (620nm) at an average intensity of 5.5x10-4 W/cm2 and dose of 0.33 J/cm2.

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Richard C. Straight "Selective photothermotherapy and spectroscopy of spectrally and spatially heterogenous biological targets with ultrafast laser pulses", Proc. SPIE 1599, Recent Advances in the Uses of Light in Physics, Chemistry, Engineering, and Medicine, (1 February 1992); https://doi.org/10.1117/12.2322300

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