What term describes closed-lipid bi-layer spheres that encapsulate active ingredients?

The term that describes closed-lipid bilayer spheres that encapsulate active ingredients is liposomes. Liposomes are unique because they are designed to enhance the delivery of active substances through the skin barrier. Formed from phospholipids, they create a structure that can trap both hydrophilic and hydrophobic ingredients within their bilayer, allowing for a more effective delivery system in topical formulations.

This encapsulation method provides various advantages, such as stabilizing the active ingredients, protecting them from degradation, and helping them penetrate the skin more effectively. The use of liposomes is particularly common in cosmetic and pharmaceutical products, as they can improve the bioavailability and efficacy of ingredients, leading to better results for the user.

Micelles, on the other hand, are structures formed by surfactant molecules that allow for solubilization of oil in water but do not encapsulate ingredients in the same way liposomes do. Emulsions consist of mixtures of oil and water stabilized by emulsifiers, while serums are typically concentrated liquid preparations that deliver active ingredients but are not characterized by the encapsulation method inherent to liposomes.