Unimolecular micelles: Synthesis and characterization of amphiphilic polymer systems

Unimolecular micelles were successfully synthesized from mucic acid, fatty acids, and poly(ethylene glycols) to create biocompatible polymers. These p olymers consist of a core-shell structure that resembles conventional micel lar structures but with significant thermodynamic stability in aqueous medi a. The core of the polymers provide a hydrophobic environment for drug enca psulation via hydrophobic interactions, whereas the shell provides excellen t water solubility. The polymers were characterized by nuclear magnetic res onance, infrared and mass spectroscopies, as well as gel permeation chromat ography, differential scanning calorimetry, and thermogravimetric and eleme ntal analyses. Encapsulation ability was measured using high-pressure liqui d chromatography to monitor Lidocaine, a hydrophobic molecule. Encapsulatio n capabilities increased as lipophilicity of the core increased. To verify that encapsulation was caused by individual unimolecular micelles, surface tension and dynamic light scattering measurements were performed. The resul ts indicated that these unimolecular micelles have great potential as drug carriers. (C) 1999 John Wiley & Sons, Inc.