nouvelles-1 — Biochemistry

Research Summary: Human skin has unique properties, with one of the most apparent being its role as a physicochemical barrier. The human integument is capable of resisting the penetration of many molecules. However, smaller molecules, particularly, can surpass the skin transcutaneously. These molecules are able to bypass the corneal layer, which is thought to serve as the main deterrent. We argue that the molecular weight (MW) of a compound must be under 500 Dalton to allow for skin absorption. Larger molecules are unable to penetrate the corneal layer. Arguments for this "500 Dalton rule" include: 1) Virtually all common contact...

Research Summary: Objectives: Diethyltoluamide and ethylhexyl p-methoxycinnamate (OMC) are two active ingredients commonly found in insect repellent and sunscreen products, respectively. The concurrent application of these two substances often increases their systemic absorption, compromising the safety and efficiency of cosmetic products. In this study, diethyltoluamide and OMC were incorporated into solid lipid nanoparticles, a colloidal drug delivery system, to reduce percutaneous absorption, avoid toxic effects, and maintain the efficacy of the two active compounds on the skin surface for a long duration. Methods: Solid lipid nanoparticles were prepared using an ultrasonication technique and characterized by differential scanning calorimetry (DSC) analyses....