title: Microgel-based engineered nanostructures and their applicability with template-directed layer-by-layer polyelectrolyte assembly in protein encapsulation.
abstract: A novel strategy for the fabrication of microcapsules is elaborated by employing biomacromolecules and a dissolvable template. Calcium carbonate (CaCO(3)) microparticles were used as sacrificial templates for the two-step deposition of polyelectrolyte coatings by surface controlled precipitation (SCP) followed by the layer-by-layer (LbL) adsorption technique to form capsule shells. When sodium alginate was used for inner shell assembly, template decomposition with an acid resulted in simultaneous formation of microgel-like structures due to calcium ion-induced gelation. An extraction of the calcium after further LbL treatment resulted in microcapsules filled with the biopolymer. The hollow as well as the polymer-filled polyelectrolyte capsules were characterized using confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), and scanning force microscopy (SFM). The results demonstrated multiple functionalities of the CaCO(3) core - as supporting template, porous core for increased polymer accommodation/immobilization, and as a source of shell-hardening material. The LbL treatment of the core-inner shell assembly resulted in further surface stabilization of the capsule wall and supplementation of a nanostructured diffusion barrier for encapsulated material. The polymer forming the inner shell governs the chemistry of the capsule interior and could be engineered to obtain a matrix for protein/drug encapsulation or immobilization. The outer shell could be used to precisely tune the properties of the capsule wall and exterior. [Diagram: see text] Confocal laser scanning microscopy (CLSM) image of microcapsules (insert is after treating with rhodamine 6G to stain the capsule wall).
authors.affiliation: Max Planck Institute of Colloids and Interfaces, D-14424, Potsdam/Golm, Germany.
authors.forename: Dinesh B
authors.initials: DB
authors.lastname: Shenoy
authors.forename: Gleb B
authors.initials: GB
authors.lastname: Sukhorukov
mesh_terms: D000464:Alginates; D002214:Capsules; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures; D036103:Nanotechnology; D011108:Polymers; D011506:Proteins / Q000008:administration & dosage*
chemical_list: D000464:Alginates; D002214:Capsules; D006603:Hexuronic Acids; D011108:Polymers; D011506:Proteins; D020723:Glucuronic Acid