Micelles formed from amphiphilic copolymers are promising materials for the delivery of drug molecules, potentially leading to enhanced biological properties and efficacy. In this work, new poly(ester amide)-poly(ethylene oxide) (PEA-PEO) graft copolymers were synthesized and their assembly into micelles in aqueous solution was investigated. It was possible to tune the sizes of the micelles by varying the PEO content of the polymers and the method of micelle preparation. Under optimized conditions, it was possible to obtain micelles with diameters less than 100 nm as measured by dynamic light scattering and transmission electron microscopy. These micelles were demonstrated to encapsulate and release a model drug, Nile Red, and were nontoxic to HeLa cells as measured by an MTT assay. Overall, the properties of these micelles suggest that they are promising new materials for drug delivery systems.

The use of polymeric nanoparticles to encapsulate and deliver drug molecules is a promising approach for improving drug properties such as water dispersibility, pharmacokinetics, and selectivity for the in vivo target. Described here is the development of poly(ester amide) (PEA) nanoparticles prepared from PEAs with pendant functional groups that allow for covalent conjugation of the drugs in order to mitigate the undesirable burst release of drug, commonly observed for nanoparticle-based drug delivery systems. Parameters including the surfactant and PEA concentration in an emulsification-evaporation procedure were studied in order to determine conditions for preparing particles with diameters < 200 nm. A hydroxylfunctionalized rhodamine derivative, as a model drug, was then conjugated to a PEA having pendant carboxylic acid groups to afford a PEA-rhodamine conjugate with the dye covalently attached by ester linkages. The emulsification-evaporation procedure was used to prepare nanoparticles from this conjugate and these particles were found to release the dye much more slowly and without a burst effect, in comparison with analogous nanoparticles having the rhodamine physically encapsulated. The same approach was applied to the anti-cancer drug floxuridine and the resulting nanoparticles also afforded sustained drug release. This work suggests the promise of PEAs with pendant functional groups for providing nanoparticle-based drug delivery vehicles with slow and sustained drug release.