PREPARATION OF STERICALLY STABILIZED NANOPARTICLES BY DESOLVATION FROM GRAFT-COPOLYMERS

A new method is described for the preparation of sterically stabilized nanoparticles of defined size and polydispersity which are stabilized in aqueous solution by the presence of covalently linked monomethoxy–poly (oxyethylene) (MeOPOE) chains. The nanoparticles (100–270 nm mean diameter) were prepared by a process of desolvation of a graft copolymer prepared from poly(2‐aminoethylmethacrylate) (PAEMA) and MeOPOE. Reproducible desolvation was achieved by the addition of sodium phosphate buffer to the copolymer in aqueous solution to give particles which were crosslinked in situ with the addition of glutaraldehyde. The size (mean diameter) and polydispersity (Q) of the particles were determined by Photon Correlation Spectroscopy (PCS). The temperature at which the desolvation reaction was performed was found to influence the particle size; at low temperatures (5–12°C), small particles were produced (99–121 nm, Q = 0.090–0.121), whereas at much higher temperatures (40–55°C), particles as large as 224–275 nm (Q = 0.138–0.127) were generated. Other parameters such as the graft copolymer concentration, the amount of glutaraldehyde added, the pH of the sodium phosphate buffer added, and the reaction time were found to be of relative insignificance in influencing the particle size. In addition to those involved in drug delivery, our method of nanoparticle preparation may be of interest to those engaged in the preparation of particulate materials and colloidal dispersions for other specific applications (e.g. stabilized photographic emulsions). Copyright © 1990 John Wiley & Sons, Inc.