Preparation and characterization of P(MAA-g-EG) nanospheres for protein delivery applications

Novel complexation hydrogel nanospheres of poly(methacrylic acid-grafted-poly(ethylene glycol)) (P(MAA-g-EG)) were prepared by dispersion polymerization to be used for protein delivery applications. Polymerization was conducted in solvents such as deionized water, ethanol/water, sodium hydroxide, hydrochloric acid, and acetic acid solutions. When polymerizing in deionized water we produced nanospheres without agglomeration. Photon correlation spectroscopy studies revealed that the nanospheres possessed a narrow particle size distribution and the size was inversely proportional to the concentration of poly(ethylene glycol) incorporated in the monomer mixture. These nanospheres exhibited pH-sensitivity comparable to that encountered in hydrogel films with the same composition. The composition of the nanospheres was investigated by transmission Fourier transform infrared spectroscopy. The comparison between hydrogel films and nanospheres with the same monomer composition revealed that nanospheres possessed similar spectral characteristics than hydrogel films prepared by the same techniques. These nanospheres could be used for calcitonin release under physiological conditions.