Core-shell functional nanospheres for oligonucleotide delivery. III. Stealth nanospheres

Polymthyl methacrylate-based stealth and functional nanospheres, specifical ly designed for the reversible adsorption of oligonucleotides (ODN), were p repared by emulsion polymerization of methyl methacrylate in the presence o f an ionic comonomer, namely a quaternary ammonium salt of 2-(dimethylamino )ethyl methacrylate, and a nonionic comonomer, namely a poly(ethylene glyco l) methacrylate. The nanosphere size is substantially affected by the amoun t of both the nonionic and ionic comonomers. By appropriately adjusting the concentrations of the ionic and nonionic comonomers, the quaternary ammoni um group and PEG chain surface densities can be finely tuned. Accordingly, a great variety of core-shell-type nanospheres, able to bind ODN and to ind uce dysopsonic effect, can be obtained. (C) 2000 John Wiley & Sons, Inc.