Degradation of methoxy-poly (ethylene glycol)-block-poly(α-carboxyl-ε-caprolactone)/magnetite nanocomposites in vitro polymer degradation and stability

Methoxy-poly (ethylene glycol)-block-poly (α-carboxyl-ε-caprolactone)/Fe 3 O 4 nanocomposites (mPEG-b-PCCL@Fe 3 O 4 ) with spherical shape, more negative and smoother surface and core-sell structure were prepared by simply changing the solvent. Their degradation behavior was systematically investigated at 37 °C in distilled water and buffers with different pH values. The mPEG-b-PCCL micelles were used as the contrast. Although the acid inhibition and basic promoting degradation were observed for both mPEG-b-PCCL@Fe 3 O 4 and micelles, the existence of magnetite nanoparticles (MNPs) and more surface –COOH slowed down the degradation of nanocomposites due to the dissociation hindrance of –COOH, the hydrophobicity and the cross-linking effects of MNPs. The degradation of mPEG-b-PCCL@Fe 3 O 4 underwent the surface degradation at initial time and bulk degradation after complete swelling of the hydrophobic core. These investigations suggested that the degradation of mPEG-b-PCCL@Fe 3 O 4 was more designable and controllable than that of micelles.