By The Cosmetic Chemist Staff
June 15, 2016
3-D printing technology has been all of the rage in the tech industry the last couple of years. From the printing of high tech designs to human organs, much promise is expected from 3-D printing in the future. In the personal care industry, a lot of excitement was generated last year when L’Oréal announced plans to develop 3-D printing technology that would allow them to print skin tissue that could be used for safety and efficacy testing. More recently, a group at University College London demonstrated the use of 3-D printing for the development of topical drug delivery systems.1
Essentially, this approach consists of obtaining a 3-D scan of a persons face—utilizing 3-D laser scanning technology—and then generating a flexible mask by 3-D printing, which conforms very well to the anatomy of the subject. Drugs, or actives, can be embedded in the mask and delivered to the skin in a controlled manner by placing the mask at the delivery point of interest. The delivery of functional ingredients in this manner may offer advantages over traditional delivery forms. For example, quick placement of a mask over a targeted body part is less time consuming and less messy than rubbing in an emulsion, which might contain surfactants that could cause skin irritation.
The 3-D printing technologies used to carry out these studies were Fused Deposition Modeling and Stereolithography. Fused Deposition Modeling is a technique in which a tubular-shaped polymeric filament is fed into the 3-D printer, resulting in a printing process where additive layers form the foundation of the printed object. Stereolithography, on the other hand, is an alternative technology in which a liquid resin is solidified during the printing process by photopolymerization reactions. Essentially, a laser is used to initiate the polymerization, resulting in the solid, printed material.
In the masks produced by Fused Deposition Modeling, the drug (in this case salicylic acid) is embedded in poly(caprolactone) and a flexible poly(lactic acid) material (Flex EcoPLA™) that are used as the raw materials for the printing process. In the stereolithography process, salicylic acid is dissolved in liquid poly(ethylene glycol) diacrylate and poly(ethylene glycol), which undergo photopolymerization during the printing procedure.
In this particular study, the masks were actually in the shape of a nose and did not cover the entire face. In addition to other metrics, the authors were able to predict diffusion of drugs into the skin by conducting Franz cell diffusion experiments. Overall, the printing resolution and drug loading capacity were superior in the stereolithography printing process, and for these reasons, this method of printing offers the most hope for future endeavors in this type of approach to the delivery of actives to the skin.