Drug co-loading and pH-sensitive release core-shell nanoparticles via layer-by-layer assembly.

Multifunctional core-shell nanoparticles are widely used for biomedical and catalytic applications. In this work, bilayers of chitosan (Cs) and phosphorylated polyvinyl alcohol (PPVA) were sequentially deposited on 3-Aminopropyltri-ethoxysilane-modified SiO2 nanoparticles via layer-by-layer electrostatic self-assembly. The good spherical shape and size distribution were observed by DLS and transmission electron microscope analysis. 7-Hydroxycoumarin (7-HC) and rhodamine B (RhB) as model drugs were loaded in the core and shell of the nanoparticles separately. Confocal laser scanning microscopy shows the core-shell structure of HC-SiO2(PPVA/Cs)n-RhB nanoparticles and the embedded location of 7-HC and RhB. The pH-sensitive release investigation of RhB indicates that the release profiles of RhB from HC-SiO2(PPVA/Cs)3PPVA-RhB core-shell nanoparticles are totally different at pH values of 2.0, 7.4, and 9.2. These results predict that the multifunctional nanoparticle SiO2(PPVA/Cs)n has a great potential for drug delivery.