Yimeng Jiao1, Milica Stevic1, Slobodanka Tamburic1
1- London College of Fashion, University of the Arts, London
3D printing enables precise layer-by-layer deposition of materials to create three-dimensional objects. While well-recognised in pharmaceutical delivery systems such as wound dressings and tablets, its potential in cosmetics is underexplored. This study examines 3D printing for producing and delivering active ingredients in cosmetic products.
Fused deposition modeling (FDM), the most affordable and studied 3D printing technology, with a broad selection of thermoplastic materials, is ideal for cosmetic applications. Therefore, FDM was used to fabricate innovative skin delivery systems in this study, with future applications of customisable, reusable eye patches and face masks.
Dual-material FDM printing allows two-part skin patches to be fabricated in a single step. Tough polylactic acid (PLA) filament served as the backing material, while biocompatible polyvinyl alcohol (PVA) filaments were used for hydrophilic patches, allowing complex designs that fit facial contours.
Six gelling agents were used to prepare 18 hydrogel formulations. These included polysaccharides (carrageenan at 2.3%-2.9% w/v, guar gum at 1.2%-1.9% w/v, and xanthan gum at 3.2%-6.4% w/v), cellulose derivatives (hydroxyethyl cellulose at 1.4%-2.2% w/v and sodium carboxymethyl cellulose at 3.2%-4.4% w/v), and a polyacrylate synthetic gelling agent (sodium polyacrylate at 0.7%-1.0% w/v). The gel formulations were characterised using a Haake™ Rheometer (MARS iQ Air, Thermo Scientific, Germany) with serrated parallel plates, employing continuous flow and oscillatory methods. These gels were then loaded onto 3D printed patches to test their efficacy as controlled-release delivery systems.
In vitro release tests were conducted using the vertical Diffusion Cell Test System, model HDT 1000 (Copley Scientific™, UK) to study the release profiles of caffeine, a model cosmetic active compound. Two types of membranes were tested: simple cellulose acetate membranes and synthetic, skin-mimicking multi-layer Strat-M membranes.
The conditions necessary for the successful production of 3D printed cosmetic patches using FDM technology were defined and optimised. Rheological characterisation, alongside caffeine release results, confirms a significant impact of rheological parameters on the release kinetics of hydrophilic actives. Controlled release was achieved by the combined effects of the 3D printed patch and caffeine-containing hydrogel. Sodium polyacrylate 0.7% gel showed a significant 63% reduction in maximum flux from the hydrogel/PVA system compared to the hydrogel alone through Strat-M.
The type of gelling agent did not significantly affect the release when similar viscosities were employed. Higher maximum flux was observed from lower viscosity hydrogels through both types of membranes from loaded PVA patches. It is assumed that water diffusing from the lower viscosity hydrogel into the PVA patch could facilitate the entry of dissolved caffeine molecules into the PVA structure, thus reducing its availability for release. This finding could be used as a practical approach to the controlled release of hydrophilic actives from this type of delivery system.
The results of this study provide a basis for informed decision-making regarding suitable 3D printing methods, materials, and parameters. It could guide design choices for the shape and thickness of skin delivery systems and influence the selection and concentration of gelling agents in the hydrogel carriers.
