| Institution: | 1. Microencapsulation/Polysaccharides, Fraunhofer IAP, Geiselbergstr. 69, 14476 Berlin, Germany;2. Nanoparticle Technology, Fraunhofer IMM, Carl-Zeiss-Str.18-20, 55129 Mainz, Germany
These authors contributed equally to this work.;3. Nanoparticle Technology, Fraunhofer IMM, Carl-Zeiss-Str.18-20, 55129 Mainz, Germany;4. Membranes and functional films, Fraunhofer IAP, Geiselbergstr. 69, 14476 Berlin, Germany |
| Abstract: | The combination of several active substances into one carrier is often limited due to solubility, stability and phase-separation issues. These issues have been addressed by an innovative capsule design, in which nanocapsules are assembled on the microcapsule surface by electrostatic forces to form a pH-responsive hierarchical capsule@capsule system. Here, melamine-formaldehyde (MF) microcapsules with a negative surface charge were synthesized and coated with a novel MF-polyethyleneimine (PEI) copolymer to achieve a positive charge of ζ=+28 mV. This novel coating procedure allows the electrostatic assembly of negatively charged poly-l -lactide (PLLA, ζ=?19 mV) and poly-(lactide-co-glycolide) (PLGA, ζ=?56 mV) nanocapsules on the microcapsule surface. Assembly studies at pH 7 gave a partial surface coverage of PLLA nanocapsules and full surface coverage for PLGA nanocapsules. The pH-responsive adsorption and desorption of nanocapsules was shown at pH 7 and pH 3. |
