Preparation of aggregation-resistant biocompatible superparamagnetic noncovalent hybrid multilayer hollow microspheres for controlled drug release.

Biocompatible superparamagnetic polyelectrolyte hybrid hollow microspheres ((CS/Fe(3)O(4)-CA)(3)-CS-NH-CH(2)-PEG) were successfully prepared by PEGylation of multilayered polyelectrolyte hybrid shell encapsulated polystyrene sulfonate (PSS) microsphere templates fabricated by the layer-by-layer self-assembly of chitosan (CS) and citrate modified ferroferric oxide magnetic nanoparticles (Fe(3)O(4)-CA), after etching the templates by dialysis. Their hollow structure with diameter of about 200 nm was confirmed by TEM analysis. The pH and ionic strength responsive properties were retained after the PEGylation of the hollow microspheres. Furthermore, their biocompatibility and stability against aggregation and fusion in media with high ionic strength were distinctly improved. A typical anti-inflammatory drug, ibuprofen, was used for drug loading, and the release behaviors of ibuprofen in a simulated body fluid (SBF) were studied. The results indicate that the biocompatible superparamagnetic polyelectrolyte hybrid hollow microspheres ((CS/Fe(3)O(4)-CA)(3)-CS-NH-CH(2)-PEG) have a high drug loading capacity and favorable release property for ibuprofen; thus, they are very promising for application in drug delivery.