Special Section Guest Editorial: Topical Problems of Biophotonics: from Optical Bioimaging to Clinical Biophotonics (original) (raw)

Topical Problems of Biophotonics

Journal of Biophotonics, 2012

These studies are aimed at revealing the mechanisms of therapeutic effects stimulated by medium power (1-10 W) fiber laser induced hydrodynamics in water-saturated bio-tissues. Modern laser medical technologies widely employ delivery of laser radiation to the irradiated tissues via optical fibers. Optical fibers easily penetrate through needles and endoscopic channels, and lasers can be used for puncture and endoscopic operations. Several laser medical technologies (fractional photothermolysis, laser engineering of cartilages, puncture multichannel laser decompression of disc, laser intervention upon osteochondrosis, surgical treatment of chronic osteomyelitis, endovenous laser ablationб etc.) are based on the effective hydrodynamic processes in water-saturated bio-tissues. These hydrodynamic processes trigger cellular response and regenerative effects through the mechanisms of mechano-biology. We study hydrodynamic effects induced by the moderate power laser radiation in the vicinity of the heated end surface of optical fiber in water, in particular, the generation of air-vapor bubbles, effects of laser-induced filaments formation and degradation of transport optical fiber. Generation of Bubbles in Liquid. The effective hydrodynamic processes in water are related to the explosive boiling in the vicinity of the heated end surface of the fiber. The resulting bubbles with sizes ranging from several to several tens of microns have velocities of up to 100 mm/s in the vicinity of the end surface. The generation of bubbles in a capillary gives rise to the stable circulation of liquid with the period ranging from 0.2 to 1 s. At a laser power of less than 3 W, stable bubble microjets, which consist of the bubbles whose sizes range from several to ten microns, can be generated in the vicinity of the blackened end surface. Degradation of optical fiber tip. We have studied the process of degradation of optical fiber tip as a result of hydrodynamic processes caused by medium power (1-5 W) cw laser effects on connective tissues. The temperature nearby optical fiber tip can be as high as several thousands of degrees. It is shown, that such high values of temperature and pressure caused by cavitation collapse of microbubbles result in formation of nano-size diamonds on the tip and, also, in water transition to supercritical state, that promotes degradation of optical fiber tip. Formation of filaments. Medium power (0.3-8.0 W) 970 nm in wavelength laser irradiation of water with added Ag nanoparticles (in the form of Ag-albumin complexes) through 400 m optical fiber stimulates self-organization of filaments of Ag nanoparticles for a few minutes. These filaments represent themselves long (up to 14 cm) liquid gradient fibers with unexpectedly thin (10-80 ¹m) core diameter. They are stable in the course of laser irradiation being destroyed after laser radiation off. Such effect of filaments of Ag nanoparticles self-organization is rationalized by the peculiarities of laser-induced hydrodynamic processes developed in water in presence of laser light and by formation of liquid fibers.

Biophotonics in diagnosis and modeling of tissue pathologies

Proceedings of SPIE - The International Society for Optical Engineering, 2008

Biophotonics techniques are applied to several fields in medicine and biology. The laser based techniques, such as the laser induced fluorescence (LIF) spectroscopy and the optical coherence tomography (OCT), are of particular importance in dermatology, where the laser radiation could be directly applied to the tissue target (e.g. skin). In addition, OCT resolves architectural tissue properties that might be useful as tumour discrimination parameters for skin as well as for ocular non-invasive visualization.

Biophotonic technologies for noninvasive assessment of skin condition and blood microcirculation

Latvian Journal of Physics and Technical Sciences

The main results obtained at the author’s laboratory over the recent five years with respect to optical in-vivo skin assessment are reviewed. The exploited optical properties of human skin are briefly regarded, with following description of the newly developed methods and prototype devices. In particular, six non-invasive diagnostic and monitoring technologies based on skin autofluorescence photobleaching, diffuse reflectance spectrometry, multispectral skin imaging, and remission photoplethysmography have been proposed, experimentally implemented, and clinically tested. Sniegts pārskats par autora laboratorijā pēdējo piecu gadu laikā iegūtajiem in-vivo ādas optiskā novērtējuma svarīgākajiem rezultātiem. Īsumā aplūkotas dzīvas ādas optiskās īpašības, turpinājumā aprakstot jaunradītās metodes un prototipa ierīces. Piedāvātas, eksperimentāli realizētas un klīniski pārbaudītas sešas neinvazīvas diagnostikas un monitoringa tehnoloģijas, kas balstītas uz ādas autofluorescences fotoizbalē...

Biophotonics in diagnosis and modeling of tissue pathologies

2008

Biophotonics techniques are applied to several fields in medicine and biology. The laser based techniques, such as the laser induced fluorescence (LIF) spectroscopy and the optical coherence tomography (OCT), are of particular importance in dermatology, where the laser radiation could be directly applied to the tissue target (e.g. skin). In addition, OCT resolves architectural tissue properties that might be useful as tumour discrimination parameters for skin as well as for ocular non-invasive visualization. Skin and ocular tissues are complex multilayered and inhomogeneous organs with spatially varying optical properties. This fact complicates the quantitative analysis of the fluorescence and/or light scattering spectra, even from the same tissue sample. To overcome this problem, mathematical simulation is applied for the investigation of the human tissue optical properties, in the visible/infrared range of the spectrum, resulting in a better discrimination of several tissue pathologies. In this work, we present i) a general view on biophotonics applications in diagnosis of human diseases, ii) some specific results on laser spectroscopy techniques, as LIF measurements, applied in arterial and skin pathologies and iii) some experimental and theoretical results on ocular OCT measurements. Regarding the LIF spectroscopy, we examined the autofluorescence properties of several human skin samples, excised from humans undergoing biopsy examination. A nitrogen laser was used as an excitation source, emitting at 337 nm (ultraviolet excitation). Histopathology examination of the samples was also performed, after the laser spectroscopy measurements and the results from the spectroscopic and medical analysis were compared, to differentiate malignancies, e.g. basal cell carcinoma tissue (BCC), from normal skin tissue. Regarding the OCT technique, we correlated human data, obtained from patients undergoing OCT examination, with Monte Carlo simulated cornea and retina tissues for diagnosis of ocular diseases.

II EOS Topical Meeting on Physiological Optics

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Optical Properties of Skin, Subcutaneous, and Muscle Tissues: A Review

The development of optical methods in modern medicine in the areas of diagnostics, therapy, and surgery has stimulated the investigation of optical properties of various biological tissues, since the e±cacy of laser treatment depends on the photon propagation and°uence rate distribution within irradiated tissues. In this work, an overview of published absorption and scattering properties of skin and subcutaneous tissues measured in wide wavelength range is presented. Basic principles of measurements of the tissue optical properties and techniques used for processing of the measured data are outlined.

Journal of BIOPHOTONICS R E P R I N T

11 3133-9374 5-aminolevulinic acid (ALA) and its methylated ester (MAL) are the most common topical agents used in photodynamic therapy (PDT) as precursors of the photosensitizer protoporphyrin IX (PpIX). The induction of newly PpIX depends on incubation time of each photosensitizer in the tissue and the presence of high intralesional porphyrin levels is an important parameter for the PDT effectiveness. This study used laser-induced fluorescence (LIF) spectroscopy to evaluate the optimum time to light exposure of PDT mediated by ALA (20% w/w) and MAL (10% w/w) to treat malignant lesions precursors of cutaneous squamous cell carcinoma induced in mice. The therapeutic effects obtained by optimized ALA-and MAL-PDT were assessed 10 and 20 days after treatments. Higher PpIX levels were evidenced in the lesions photosensitized by ALA than MAL and according to LIF measurements the PDT irradiation was performed, respectively, at 300 and 330 minutes after ALA and MAL incubation. Histopathological analysis evidenced necrosis and epithelial atrophy after 10 days of PDT using both prodrugs, as well as reepitelization and collagen deposition at 20 days. Thus, despite the distinct concentration of ALA and MAL used in the formulation of each photosensitizing cream, PDT mediated by both photosensitizing agents obtained similar therapeutic outcomes.