Abstract:
Using the method of optical coherence tomography (OCT), results of immersion optical clearing of human skin in vivo were obtained using aqueous solutions of sorbitol, xylitol, D-xylose, and dimethyl sulfoxide (DMSO) as immersion agents. To assess the effectiveness of optical clearing, the rate of change in the scattering coefficient was determined using the averaged A-scan of the OCT signal in the dermis region at a depth of 350 to 700 $\mu$m. As a result of molecular modeling using classical molecular dynamics methods (GROMACS), the number of hydrogen bonds formed per unit time for each agent was determined, as well as the influence of these agents on the spatial volume of the collagen peptide ((GPH)$_3$)$_9$. Quantum chemistry methods HF/STO-3G/DFT/B3LYP/6-311G(d) were used to calculate the intermolecular interaction energy of immersion agent complexes with a fragment of the collagen peptide ((GPH)$_3$)$_2$, and correlations were established between the effectiveness of optical clearing and the intermolecular interaction energy. Non-classical hydrogen bonds formed during the interaction of DMSO with the collagen peptide and water molecules are discussed in detail. The effective diffusion coefficient of DMSO in rat skin ex vivo was calculated, with an average value of (4.1 $\pm$ 3.1) $\times$ 10$^{-6}$ cm$^2$/sec.
Keywords:molecular modeling, optical clearing of human skin, hydrogen bonds, molecular dynamics, quantum chemistry, immersion agents, diffusion coefficient.
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