The interaction of six low-molecular tissue-clearing agents (1,2 and 1,3-propanediol, ethylene glycol, glycerol, xylitol, sorbitol) with the collagen mimetic peptide (GPH) was studied by applying the methods of classical molecular dynamics (GROMACS), molecular docking (AutoDock Vina) and quantum chemistry (PM6 and B3LYP). The spatial configurations of intermolecular complexes were determined and interaction energies calculated. The dependence of the volume occupied by the collagen peptide on the clearing agent concentration in an aqueous solution was calculated. This dependence is not linear, and has a maximum for almost all the agents in the study. The correlations between the optical clearing potential and intermolecular interactions parameters, such as the time of an agent being in a hydrogen-bonded state, and the relative probability of formation of double hydrogen bonds and interaction energies, were determined. Using the correlations determined, we predicted the numeric value of the optical clearing potential of dextrose molecules in rat skin, which correlates with experimental data. A molecular mechanism of tissue optical clearing within the post-diffusion stage is suggested. Graphical abstract The molecular modeling of the interaction between clearing agents and collagen.

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We present the results of in vivo optical immersion clearing of human skin by aqueous solutions of some immersion agents (ribose, glucose, and fructose monosaccharides and glycerol), obtained using optical coherence tomography (OCT). To assess the efficiency of optical clearing, we determined the values of the rate of change of the light scattering coefficient, obtained using the averaged A-scan of the OCT signal in the derma section at a depth of 350–700 μm. A good correlation was observed between the rate of change of the light scattering coefficient and the potential of the optical clearing. Using complex molecular simulation of the interaction of a number of immersion clearing agents with collagen mimetic peptide (GPH)_3 using classical molecular dynamics and quantum chemistry, we found correlations between the efficiency of optical clearing and the energy of intermolecular interaction of cleaning agents with a fragment of collagen peptide.

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