OCT analysis of in vivo human skin optical clearing combined with physical and chemical permeation enhancers
Optical techniques applied to the skin providing a non-invasive and relatively fast analysis tool for getting access to morphology and optical properties of the biological tissue. Also, it was found that special biocompatible chemicals called Optical Clearing Agents (OCA) can penetrate through the skin and by dehydration, reversible collagen fibers dissociation and the refractive indices matching between intercellular and extracellular liquids may increase the depth and contrast of optical techniques. However, skin acts as the natural physiological barrier, preventing leaking in and out of the liquids, what makes it difficult to efficiently introduce the OCAs within the skin. One possible way to overcome the skin barrier for OCAs is their using in combination with the chemical and physical permeation enhancers that can create the pathways in upper skin layers, thus increasing the OCA penetration depth and speed. The goal of the study is to explore the effect of optical clearing agents combined with chemical and physical permeation enhancers on the contrast and optical depth of the OCT probing of human skin in vivo.
In the work we used 2 different combinations of optical clearing agents and chemical permeation enhancers for increasing the optical depth of OCT probing in 2 different conditions: mixtures of oleic acid and PEG - 400 in ratio 20:80 and aqueous solution of Hyaluronic Acid and PEG - 400 in ratio 20:80. Four volunteers with age between 19 and 24 years have participated in this study. For each mixture, first condition was the simultaneous application of mixture, and the second condition was the separate application of chemical permeation enhancer followed by application of OCA. Dermabrasion was applied to the skin as physical permeation enhancer before the application. Mechanical massage was used to enhance the penetration of chemicals. Optical Coherence Tomography (OCT) was used to measure the changes in vivo in skin contrast and optical depth of the OCT probing.
Saratov State University
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