The quantitative analysis of Raman spectroscopic signals in biological tissue is generally difficult. Typical samples contain a multitude of molecular species and, in addition, measurements are altered by attenuation of the Raman signal. Realistic numerical modeling of the Raman process can help to facilitate the quantitative analysis of the Raman spectra, but approaches so far are scarce and often time-consuming. In this work, we report on two different and very efficient approaches for modeling of Raman scattering in turbid media irradiated by laser light. Both approaches utilize the Monte Carlo method to simulate the Raman scattering process. We compare the efficiency of both approaches and discuss possible future extensions and experimental validation.
In this paper, we report about simulated distribution of density of absorbed light energy within human skin following light illumination with a combination of three wavelengths (310, 514 and 800 nm) with ratios similar to ultraviolet, visible and infrared fractions of the solar irradiance spectrum. We study heat distribution within the skin treated with a sunscreen containing TiO2 nanoparticles. Our results show that administration of TiO2 particles does not cause heat load on the tissue.
In this review, the optical and structural properties of biomaterials are discussed. First, we demonstrate the optical and structural properties of natural and plasma-treated DNA, using UV-visible absorption, circular dichroism (CD), and Raman spectroscopy. Fluorescence and lasing action in the dye-doped DNA-surfactant complex are also explained. Additionally, nanomaterial-based DNA detection and DNA-templated nanomaterial growth are described. Next, we discuss protein folding studies utilizing fluorescence, CD, and nuclear magnetic resonance (NMR) spectroscopy. From the CD spectra of alpha-chymotrypsin (CT), we estimate the composition of a-helices and the beta-sheets, and random coils in the CT. 1H NMR spectroscopy is used to investigate the thermal effect on the refolding of CT in the presence of an ionic liquid. Finally, we explain the numerical simulation method used for studying the optical properties of biomaterials. Applications of the Monte-Carlo method in photodynamic therapy, skin tissue optics, and bioimaging are described.
Continuous-wave laser micro-beams are generally used as diagnostic tools in laser scanning microscopes or in the case of near-infrared (NIR) micro-beams, as optical traps for cell manipulation and force characterization. Because single beam traps are created with objectives of high numerical aperture, typical trapping intensities and photon flux densities are in the order of 10(6) W/cm(2) and 10(3) cm(-2) s(-1), respectively. The main idea of our theoretical study was to investigate the thermal reaction of RBCs irradiated by laser micro-beam. The study is supported by the fact that many experiments have been carried out with RBCs in laser NIR tweezers. In the present work it has been identified that the laser affects a RBC with a density of absorbed energy at approximately 10(7) J/cm(3), which causes a temperature rise in the cell of about 7-12 °C.
Initial data for solving the problem of heating biological tissues by laser radiation are the optical characteristics of the tissues determining light regimes after irradiation, and their thermal-physical properties determining heat transfer as functions of time and depth of penetration into the medium. Based on an analysis and generalization of literature data and results of our investigations, we suggest a model of the optical and thermal-physical characteristics of the biotissues. The finite-element method is used to solve the problem of thermal conductivity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.