Correlation of Optical and Thermodynamic Methods for Detecting Skin Collagen Denaturation under IR Laser Heating
Yulia K. Sedova2, Natalia Y. Ignatieva1, Olga L. Zakharkina2, Olga I. Baum2, Alexei V. Yuzhakov2, , Alexander P. Sviridov2
1 M. V. Lomonosov Moscow State University
2 Institute of Photon Technologies Kurchatov Complex of Crystallography and Photonics NRC "Kurchatov Institute"
Abstract
Infrared laser heating is an effective method for modifying connective tissues, based on thermally induced collagen denaturation. The selection of optimal exposure parameters requires labor-intensive in vivo experiments, which can be optimized through preliminary in vitro studies. Although optical techniques enable real-time tissue monitoring, they do not provide a direct quantitative assessment of structural alterations within the collagen framework. In this work, we correlated optical signals recorded during laser exposure of rabbit skin with differential scanning calorimetry (DSC) data of treated samples and their enzymatic resistance assays.
Non-contact laser irradiation (λ = 1,560 nm, power 1–3 W, pulse duration 200 ms) of in vitro rabbit skin samples was performed with simultaneous recording of transmitted and diffusely reflected light using an integrating sphere. During irradiation, two additional types of measurements were carried out:
1. Registration of backscattered light in the visible and near-infrared ranges using a digital camera mounted on a microscope, followed by calculation of the mean intensity;
2. Analysis of speckle patterns obtained under He–Ne laser illumination (λ = 633 nm) with computation of statistical parameters.
All employed optical methods enabled reliable detection of the onset of laser heating. Upon collagen denaturation, marked changes were observed in both reflectance and transmittance signals (recorded by the integrating sphere) as well as in the camera-detected light intensity. The statistical parameters of speckle patterns clearly reflected the heating and cooling phases, while their temporal dynamics exhibited distinct characteristics before and after denaturation. These findings demonstrate that multimodal optical probing provides a sensitive tool for real-time assessment of collagen denaturation during IR laser heating of skin.
Speaker
Sedova Yulia
Institute of Photonic Technologies of the Kurchatov Complex of Crystallography and Photonics of the National Research Center “Kurchatov Institute”
Russia
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