Enhanced vitamin C skin permeation from supramolecular hydrogels, illustrated using in situ ToF-SIMS 3D chemical profiling

Abstract

<p>Vitamin C (ascorbic acid) is a naturally occurring, powerful anti-oxidant with the potential to deliver numerous</p><p>benefits to the skin when applied topically. However, topical use of this compound is currently restricted by an</p><p>instability in traditional formulations and the delivery and eventual fate of precursor compounds has been</p><p>largely unexplored. Time of flight secondary ion mass spectrometry (ToF-SIMS) is an emerging technique in the</p><p>field of skin research and offers detailed chemical analysis, with high mass and spatial resolution, as well as</p><p>profiling capabilities that allow analysis as a function of sample depth. This work demonstrates the successful use</p><p>of ToF-SIMS to obtain, in situ, accurate 3D permeation profiles of both ascorbic acid and a popular precursor,</p><p>ascorbyl glucoside, from ex vivo porcine skin. The significant permeation enhancing effect of a supramolecular</p><p>hydrogel formulation, produced from an amphiphilic gemini imidazolium-based surfactant, was also demonstrated</p><p>for both compounds. Using ToF-SIMS, it was also possible to detect and track the breakdown of ascorbyl</p><p>glucoside into ascorbic acid, elucidating the ability of the hydrogel formulation to preserve this important</p><p>conversion until the targeted epidermal layer has been reached. This work demonstrates the potential of ToFSIMS</p><p>to provide 3D permeation profiles collected in situ from ex vivo tissue samples, offering detailed analysis on</p><p>compound localisation and degradation. This type of analysis has s</p>