Copolymer nanoparticles composed of sulfobetaine and poly(ε-caprolactone) as novel anticancer drug carriers.

Novel ABA type amphiphilic copolymers (PCL-APS-PCL) consisting of polycaprolactone (PCL) (A) as hydrophobic block and N,N'-bis (2-hydroxyethyl) methylamine ammonium propane sulfonate (APS) (B) as hydrophilic segment, self-assembled into nanoparticles (NPs) with solvent evaporation method. The sizes and size distributions of NPs were characterized by dynamic light scattering. The morphology of NPs was observed by scanning electron microscopy (SEM). The critical micelle concentration (CMC) was determined by fluorescent probe. The drug loading content (DLC) and the drug release amount were characterized by UV-visible spectrophotometer. The cytotoxicity of the NPs was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylte-trazoliumbromide (MTT) assay. It was found that the NPs were spherical in shape with sizes around 100 nm. The CMCs of the copolymers were quite low (×10(-4) mg/mL). The DLC decreased with lengthening of hydrophobic PCL block. In vitro drug release experiment demonstrated that the release rate of paclitaxel sped with the decrease of PCL length. MTT results showed that NPs were nontoxic to osteoblast and human epithelial carcinoma (hela) cells. After drug loading, NPs could restrain the growth of hela or even kill hela cells. Therefore, these preliminary studies suggest that the novel PCL-APS-PCL NPs have a great potential application as anticancer drug-delivery carriers.