Preparation of poly(methacrylic acid-g-poly(ethylene glycol)) nanospheres from methacrylic monomers for pharmaceutical applications

Nanospheres of poly(methacrylic acid-grafted-poly (ethylene glycol)) were prepared by solution/precipitation polymerization. As colloidal drug deliver carriers, they present unique properties that render them promising candidates for oral protein delivery. The polymerization was carried out in water and the resulting suspension was freeze-dried. As with many colloidal systems, the freeze-dried suspension showed strong agglomeration after drying. The effects of preparation conditions on the particle size and redispersion were investigated using photon correlation spectroscopy, Furthermore, the ability of different types and concentrations of stabilizers (cryoprotectants and steric stabilizers) in preventing this phenomenon was addressed. Pluronics(R), block copolymers widely used as nonionic surfactants, were the most effective in stabilizing the particles during the freeze-drying process, Pluronic(R) P123. however, increased significantly the particle size of the nanospheres. On the other hand, lyophilizates obtained in the presence of Pluronic(R) F68 had good redispersion properties and no change in particle size was observed. (C) 2002 Elsevier Science B.V. All rights reserved.