Comparing the synergistic effects of oleic acid and dimethyl sulfoxide as vehicles for optical clearing of skin tissue in vitro.

Recently, the tissue optical clearing technique has shown great potential in enhancing the capabilities of non-invasive light-based diagnostic and imaging techniques due to increased light penetration into tissue. In order to facilitate the clinical availability of the tissue optical clearing technique by the use of hyperosmotic agents, this study introduces oleic acid, a mono-unsaturated fatty acid which is generally recognised as safe, as an enhancer, and investigates the synergistic effect of oleic acid and propylene glycol on the optical clearing of skin tissue in vitro. Experimental results from near infrared spectroscopy, mass loss measurement and skin permeability assessment show that, when compared with dimethyl sulfoxide (DMSO) as an enhancer, oleic acid has a similar clearing effect. Due to its potential toxicity and the possible side effects, DMSO has been controversial in clinical applications. Therefore, in terms of optical application and clinic safety, the results presented reveal that oleic acid could be an optimal choice as an enhancer for optical clearing of skin tissue.