Drug-delivery systems such as nicotine patches are designed to transfer substances from textiles into skin. The Hohensteiner Institute, Bönnigheim, Germany, studied various microcapsule depot structures with regard to mechanical strength, capacity to release substances in continuous and controllable amounts, and resistance to washing; staff also evaluated various casing materials and methods of applying microcapsules to textile bases, such as cotton and polyester. Elements studied were fed into an evaluation matrix to assess the effectiveness of different systems and methods of application.

Microcapsules with a small dimension and a melamine or chitosan casing combined with an appropriate binder proved to be most resistant to washing when applied to textiles. Chitosan microcapsules filled with cosmetic substances are released in sufficient quantities from microcapsule depot structures in textiles to skin, suggesting new approaches to cosmetic skincare. Encapsulation of biological substances to promote wound healing look promising for medical applications, but require further refinement to ensure that the dose control is accurate enough.

Microcapsules and their casing materials must be verified as biologically safe in accordance with EN ISO 10993, and the Hohensteiner Institute recommends that manufacturers state if microcapsules are being used and what ingredients they contain, in the interest of consumer safety.

To read more about the study results, visit the Web site at www.hohenstein.de.