Objective: The purpose of this study was the evaluation of thiolated silicone oil as novel skin protectant exhibiting prolonged residence time, enhanced barrier function and reinforced occlusivity.
Methods: Two silicone conjugates were synthesized with mercaptopropionic acid (MPA) and thioglycolic acid (TGA) as thiol ligands. Adhesion, protection against artificial urine and water vapour permeability with both a Payne cup set-up and transepidermal water loss (TEWL) measurements on porcine skin were assessed.
Results: Silicone thiomers showed pronounced substantivity on skin with 22.1 ± 6.3% and 39.2 ± 6.7% remaining silicone after 8 h for silicone-TGA and silicone-MPA, respectively, whereas unmodified silicone oil and dimethicone were no longer detectable. In particular, silicone-MPA provided a protective shield against artificial urine penetration with less than 25% leakage within 6 h. An up to 2.5-fold improved water vapour impermeability for silicone-MPA in comparison with unmodified control was discovered with the Payne cup model. In addition, for silicone-MPA a reduced TEWL by two-thirds corresponding to non-thiolated control was determined for up to 8 h.
Conclusion: Thiolation of silicone oil leads to enhanced skin adhesiveness and barrier function, which is a major advantage compared to commonly used silicones and might thus be a promising treatment modality for various topical applications.
Keywords: TEWL; chemical synthesis; polymers; silicone oil; skin adhesive; skin barrier.
© 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.