Abstract
The present study aimed at exploring the use of amine‐containing core‐shell nanoparticles as potential drug carriers for intracellular delivery. Stable nanoparticles (100–200 nm in diameter) that consisted of poly(methyl methacrylate) (PMMA) cores with hydrophilic poly(ethyleneimine) (PEI) shells were synthesized and used to study their complexation with model drug, ibuprofen (IB), and release it under various electrolyte concentrations. The complexed IB/PEI–PMMA nanoparticles were characterized with FTIR, photon correlation spectroscopy, ζ‐potential, and transmission electron microscopy (TEM). Results suggested that the PEI–PMMA nanoparticles could effectively complex with the IB via electrostatic interaction. The thick PEI shells (∼30 nm) significantly enhanced the drug loading capacity up to 23% (w/w) of the complexed nanopartricle. In vitro release of the drug from the complexed nanoparticles was sensitive to the ionic strength of the media. Study of cellular entry of fluorescently labeled IB/nanoparticle complexes using a confocal laser scanning microscopy demonstrated that the entry of the complexed nanoparticles strongly depended on the complexing ratio between IB and PEI–PMMA nanoparticles. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2007