| Regional Biophysics Meeting 2005, March 16-20, Zreče, Slovenia | [NanoBioTech] |
Polyelectrolyte capsules have been recently proposed as a novel type of nano-engineered multifunctional materials. These capsules are made by layer-by-layer adsorption of oppositely charged polyelectrolytes on the surface of colloidal template particles of 0.05 – 20 mm diameter with sequential removal of the template core. A great variety of materials including synthetic and natural polyelectrolytes, proteins, multivalent ions, organic nanoparticles, lipids were used to build walls of hollow capsules. Many of them were functionalized to provide special surface properties of technical or biological relevance. The possibility of tailoring different functionalities, impregnating inorganic and organic substances both inside capsule volume and in polyelectrolyte shell, controlled release of encapsulated material provided continuous scientific and industrial interest for employing capsules as microcontainers and microreactors. Varying pH, ionic strength of the solution and using mixtures of two and more solvents, it makes possible to switch open/closed state of pre-formed capsule shell and to introduce desired reagent inside. Then the second reagent is added, that results in product synthesis either in capsule volume or in the shell. By this approach we have synthesized different magnetite and purely metal particles, fluorites of rare-earth elements, hydroxyapatites and metal nanoparticles in this micron-sized volumes. Inorganic nanoparticles incorporated to polyelectrolyte shell makes possible the remote activated release. Here we present the results obtained with hollow and filled capsules prepared with stimuli-responsive polymers and capsules filled with different polymers responsive to ions, pH and temperature. The possibilities for practical applications of such capsules are illustrated.
Email: gleb@mpikg-golm.mpg.de
Address: Max Planck Institute of Colloid and Interfaces, 14424, Potsdam/Golm, Germany,