Nanoparticles for paclitaxel delivery: a comparative study of different types of dendritic polyesters and their degradation behavior.

The aim of this study was to formulate nanoparticles from three different hyperbranched polymers, namely an unmodified dendritic polyester (Boltorn H40™), a lipophilic, fatty acid modified dendritic polymer (Boltorn U3000™) and an amphiphilic dendritic polymer (Boltorn W3000™) for drug delivery of paclitaxel and to investigate their properties. A solvent displacement method allowed preparation of nanoparticles from all three hyperbranched polymers. Nanoparticle sizes ranged from 70 to 170 nm. The lipophilic Boltorn U3000™ formed the biggest nanoparticles and the amphiphilic Boltorn W3000™ formed the smallest ones. Nanoparticles of amphiphilic Boltorn W3000™ displayed only a slightly negative zeta potential, while more negative zeta potentials were measured for nanoparticles based on the other two polymers. Degradation profiles were investigated by short time pH-stat titration. Boltorn H40™ showed a faster degradation rate then the two other fatty acid containing polymers. For Boltorn H40™, degradation rate was also investigated in longer term mass loss studies resulting in 30% degradation during 3 weeks. Cytotoxicity of the nanoparticles was studied by MTT assay displaying low cytotoxicity for all three polymers. All three types of nanoparticles were loaded with paclitaxel and their release profiles were studied. Sizes and zeta potentials remained stable after loading and did not change significantly. These three types of hyperbranched polymers show potential as nanoparticulate delivery systems and should be further studied. Due to their high loading efficiency, Boltorn U3000 and W3000 represent the most interesting candidates.