Crosslinked polysaccharide nanocapsules: preparation and drug release properties

Crosslinked polysaccharide and composite polysaccharide capsules with diameters ranging from 200 nm to several microns and wall thicknesses of several tens of nanometers have been fabricated by interfacial polymerization of methacrylated N,N-diethylaminoethyl dextran (DdexMA) and DdexMA-vinyl terminated polylactide macromonomers (PLAM). In this method, chloroform droplets or PLAM-containing chloroform droplets were dispersed in water, on which water soluble DdexMA was polymerized to form closed shell structure. Their hollow nature was confirmed by confocal laser scanning microscopy and transmission electron microscopy. Dynamic light scattering revealed that these capsules possess good stability against coagulation during storage. Fourier transform infrared and elemental analysis found that the DdexMA capsules were actually composed of crosslinked DdexMA, while the DdexMA-PLAM capsules were composed of the crosslinked DdexMA-PLAM copolymers and PLAM. By dissolution of ibuprofen in the chloroform droplets, drug-loaded capsules were also fabricated. It was found that the loaded drug could be released again in a sustained manner for up to 100 h. The capsule walls had a prominent effect in slowing down the drug release rate, particularly for the DdexMA-PLAM capsules.