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Spectral evaluation of laser‐induced cell damage with photothermal microscopy
Author(s) -
Lapotko Dmitri O.,
Zharov Vladimir P.
Publication year - 2005
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.20119
Subject(s) - photothermal therapy , laser , materials science , propidium iodide , fluence , optics , irradiation , optoelectronics , nanosecond , wavelength , microscopy , chemistry , nanotechnology , programmed cell death , apoptosis , biochemistry , physics , nuclear physics
Background and Objectives Determining cell photo‐damage is important for laser medicine and laser safety standards. This work evaluated the potential of photothermal (PT) technique for studying invasive laser‐cell interaction, with a focus on PT evaluation of spectral dependence of laser‐induced damage in visible region at single intact cell level. Study Design/Materials and Methods PT is based on irradiation of a single intact cells with a tunable pump laser pulse (420–570 nm, 8 nanoseconds, 0.1–300 μJ) and monitoring of temperature‐dependent variations of the refractive index with a second, collinear probe beam in pulse (imaging) mode (639 nm, 13 nanoseconds, 10 nJ), and continuous (integrated PT response) mode (633 nm, 2 mW). The local and the integrated PT responses from the individual living red blood cells, lymphocytes, and cancer cells (K562) in vitro were obtained at different pump laser fluence and wavelength and compared with data obtained by conventional viability tests (Annexin V—propidium iodide). Results The cell damage with pump pulse lead to specific change in PT response's temporal shape and PT image's structure. The photodamage thresholds varied in the range of 0.5–5 J/cm 2 for red blood cells, 4.4–42 J/cm 2 for lymphocytes, and 36–90 J/cm 2 for blast cells in the pump wavelength range of 417–555 nm. Conclusion Damage threshold at different wavelength depends on absorption spectra of cells. Spectral evaluation of laser‐damage thresholds can be done in two supplements for each PT mode—PT imaging and integrated PT response. The correlation between specific change of PT parameters and cell damage permits using PT technique to rapidly estimate the invasive conditions of the laser‐cell interactions. Lasers Surg. Med. 36:22–30, 2005. © 2005 Wiley‐Liss, Inc.