Laser-induced fluorescence (LIF) spectra of calcified human heart-valve tissue and LIF spectra of macroscopic calcinosis fragments dissected from human heart valves were compared with LIF spectra of pig myocardium tissues. Excitation was provided by an excimer laser with wavelength lambda = 248 nm. Fluorescence bands that were due to mineral and organic tissue components were identified by measurement of LIF spectra of macroscopic fragments of calcified tissues that had been heat treated at 700 degrees C. The studies showed that LIF spectra of calcified tissues include fluorescence emission from tryptophan, collagen, elastin, and a mineral component of tissue, hydroxylapatite. The observed differences in LIF spectra of normal and calcified tissues with different pathologies may result not only from calcification-induced changes in relative collagen and elastin concentrations but also from additional (absent in normal heart tissue) fluorescence of hydroxylapatite. The calcification-induced changes in the LIF spectra of human heart-valve tissues, characterized by a 330/450 nm ratio, were found to be quite appreciable, which suggests that this ratio can be used with LIF measurements to evaluate the degree of heart-tissue calcification.

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A simple two-component model is worked out to investigate pulsed laser-induced fluorescence in complex organic samples, like biological tissues, optically thick at the excitation wavelength. Expression for emitted fluorescence signal is obtained. Saturation process is shown to be determined not only by fluorophores excited by the laser, but non-fluorescent chromophores with overlapping absorption band as well. For homogeneous samples the forms of saturation curves are determined by fluorophore's features. Experimental saturation curves of bulk paper and mice tissues ultraviolet pulsed laser-induced fluorescence are discussed considering this model. For the ns and shorter laser pulse durations with wavelength in 200-300 nm region, pulse energy density should be less than 200 μJ/cm for correct quantitative comparison of fluorescence spectra of biological tissues with primarily tryptophan fluorescence.

Excitation-emission matrices of laser-induced fluorescence of lens capsule epithelium, the lens nucleus, and the lens capsule are investigated. A solid-state laser in combination with an optical parametric generator tunable in the range from 210 to 350 nm was used for excitation of fluorescence. The spectra of fluorescence of all three types of tissues exhibit typical features that are specific to them and drastically differ from one another. This effect can be used for intrasurgical control of presence of residual lens capsule epithelium cells in the capsular bag after surgical treatment of a cataract.