Amphiphilic diblock copolymeric nanospheres composed of methoxy poly(ethylene glycol) and glycolide: properties, cytotoxicity and drug release behaviour

Amphiphilic diblock copolymers based on methoxy poly(ethylene glycol) (MePEG) and glycolide with different molar composition were synthesized by bulk polymerization without any catalysts. Using diblock copolymers, we have prepared indomethacin-loaded polymeric nanospheres by forming a micelle in selective solvents. The size of nanospheres measured using dynamic light scattering exhibited a narrow monodisperse size distribution and an average diameter in the range of less than 200 nm. The critical micelle concentration (CMC) of MG70 sample determined by fluorescence spectroscopy was 1.57×10-7 mol/l which was lower than the CMC of common low molecular weight surfactant. In vitro release experiments using indomethacin-loaded MePEG/glycolide nanospheres exhibited the sustained release behaviour without any burst effect. In addition, the results of cytotoxicity tests using an MTT assay method showed that these MePEG/glycolide nanospheres could remarkably reduce cell damage compared with unloaded free drug.