Encapsulation of fragrances in micron-size silk fibroin carriers via coaxial electrohydrodynamic techniques

Herein, we present the successful application of coaxial electrostatic atomization technology for encapsulation of volatile fragrances in silk fibroin (SF) matrices with l-menthol (MenOH) as a model compound. The fragrance-loaded core-shell fibers and capsules of a mean diameter of 1-2 mu m were fabricated on the same apparatus, and their structural characteristics could be tuned by changing the ratio of a component in core and shell and matching with process parameters. By decreasing the concentration of the core solution, the loading capacity (LC) of electrospun fibers was up to 12 wt% with an encapsulation efficiency (EE) of similar to 46%. The fragrance content of capsules was 4% since a limited amount of MenOH incorporated in the case of electrospray. Impregnation with alcohol was effective in hardening SF shell and thus significantly decreasing the diffusion of aroma molecules. The fragrance release profile and rate of the composites were controlled by the degree of crystallinity of SF matrix and the shell thickness. Also, the fragrance microcapsules could be directly deposited on the fabric surface during electrospray and showed good washing durability.

Automated summary

Coaxial electrostatic atomization technology was successfully used to encapsulate volatile fragrances in silk fibroin matrices with l-menthol as a model compound. The fragrance-loaded core-shell fibers and capsules were fabricated with controllable structural characteristics. The fragrance release profile and rate were influenced by the degree of crystallinity of SF matrix and the shell thickness.