Dendrimersomes for Ingredient Delivery

By: Katie Schaefer, C&T magazine

Posted: June 29, 2010, from the July 2010 issue of Cosmetics & Toiletries.

In recent years, encapsulation to deliver cosmetic ingredients into the skin has boomed. However, to deliver an ingredient into the epidermis, the vehicle must mimic biological cell membranes that comprise phospholipids, carbohydrates, cholesterol, proteins, etc. Therefore, interest has grown in structures that mimic the cell membrane. In addition, those that monodisperse and can be triggered to release their contents under various conditions improve delivery as well as formulation flexibility.

Thus far, polymersomes and liposomes have been introduced—vesicles capable of delivering drugs and cosmetic actives into the skin. However, they challenge chemists and formulators in terms of stability, dispersion and methodology. According to Virgil Percec, PhD, a professor at the University of Pennsylvania, dendrimers are the answer to the stable, effective delivery of drugs and cosmetic actives to the skin. Percec’s team has researched the fundamentals of dendrimers for years but more recently published work on using dendrimers to deliver drugs, cosmetic ingredients and other materials to the skin.

Comparing Delivery Vesicles
Vesicles that mimic the biological cell membrane often are generated by a complicated methodology, according to Percec, since each drug release application requires a particular vesicle size. He went on to describe the challenges of delivering materials using liposomes and polymersomes. While polymersomes are stable in solutions when assembled into vesicles, according to Percec, they pose dispersion problems. “Polymersomes polydisperse and require tedious fractionation in order to get monodispersion for specific applications,” said Percec. He added that most polymers are not biocompatible.

Similar to polymersomes, liposomes must be fractionated; however, they are not as stable as polymersomes or they are stable for a shorter period of time. “People have come up with methods to stabilize them, but they are not straight forward,” added Percec.

Percec’s team therefore sought to create a vesicle that mimicked the biological cell membrane but solved the problems of stability, dispersion and the methodological challenges associated with other vesicles. The team sourced dendrimers for this task—specifically Janus dendrimers, and using the nomenclature that preceded them, they termed these vesicles dendrimersomes.