Synthesis and evaluation of star-shaped poly(ϵ-caprolactone)-poly(2-hydroxyethyl methacrylate) as potential...

Novel star-shaped poly(ϵ-caprolactone)-b-poly(2-hydroxyethyl methacrylate) (sPCL-b-PHEMA) with 3 arm and 6 arm was synthesized by a combination of ring-opening polymerization and atom transfer radical polymerization. The structure of copolymers was confirmed by nuclear magnetic resonance ((1)H and (13)C NMR) and Fourier transform infrared spectroscopy. The thermal behavior was measured by differential scanning calorimetry. The results showed that Tc, Tm, and Xc of the sPCL-b-PHEMA were reduced along with the increase in the length of the PHEMA block. The copolymers could self-assemble into dispersed micelles with quite low (×10(-4)mg/mL) critical micelle concentration. The size and morphology of the micelles were characterized by dynamic light scattering and HAADF scanning transmission electron microscopy. It was found that the micelles were around 20-70 nm with a regular spherical shape. Moreover, drug loading content and encapsulation efficiency of paclitaxel by 3sPCL-b-PHEMA micelles were much lower than the values of 6sPCL-b-PHEMA micelles. The drug release experiments demonstrated that paclitaxelrelease was two-phase release profile and relative to the structure of sPCL-b-PHEMA.The in vitro cytotoxicity of sPCL-b-PHEMA micelles was evaluated using methylthiazoletetrazolium assay. The results showed no apparent inhibition effect on the Hela cells. These preliminary studies suggest that sPCL-b-PHEMA has a possible application as anticancer drug delivery carriers.