Nanoemulsion-Loaded Capsules for Controlled Delivery of Lipophilic Active Ingredients

Nanoemulsions have gained considerable attention in recent years because of the increasing need for delivering lipophilic active ingredients that are ubiquitous and indispensable in pharmaceutical, cosmetic, and food applications. However, lipophilic active ingredients are hydrophobic in nature, which limits their bioavailability and absorption efficiency. Nanoemulsions featuring their uniform nanodroplets can not only address the bioavailability issue but also provide high solubilization capacity and enhanced stability. Building on these ideal properties of nanoemulsions, encapsulation technologies have been developed to formulate nanoemulsions into dosage forms for incorporating more benefits: accurate administration, controlled delivery, and enhanced stability. Nevertheless, nanoemulsion encapsulation techniques are limited to monolithic dosage forms, and the lack of versatile carrier platforms for nanoemulsions hinders advanced control over their release behavior.

In this work, a method is developed to encapsulate nanoemulsions in alginate capsules for the controlled delivery of lipophilic active ingredients. Functional nanoemulsions loaded with active ingredients and calcium ions are first prepared, followed by encapsulation inside alginate shells. The intrinsically high viscosity of the nanoemulsions ensures the formation of spherical capsules and high encapsulation efficiency during the synthesis. A facile approach is developed to measure the nanoemulsion release profile from capsules through UV-Vis measurement without an additional extraction step. A quantitative analysis of the release profiles shows that the capsule systems possess a tunable, delayed-burst release. The proposed encapsulation methodology can be further generalized to other functional nanoemulsions with various active ingredients, oil phases, nanodroplet sizes, and chemically crosslinked inner hydrogel cores. Overall, the capsule systems provide promising platforms for various functional nanoemulsion formulations.