title: Fabrication of hybrid nanocapsules by calcium phosphate mineralization of shell cross-linked polymer micelles and nanocages.
abstract: Self-assembled shell cross-linked poly(acrylic acid-b-isoprene) (PAA78-b-PI97) micelles or cross-linked PAA nanocages in aqueous solution were used as templates for the preparation of novel polymer-inorganic nanocapsules. The hybrid nanostructures were typically 50-70 nm in diameter and consisted of spherical polymer nanoparticles or nanocages enclosed within a continuous 10-20 nm thick surface layer of amorphous calcium phosphate. Nucleation of calcium phosphate specifically in association with the polymer nanoparticles was facilitated by low supersaturation levels and by sequestration of Ca2+ ions within the carboxylate-rich PAA domains prior to addition of HPO4(2-). Modifications in ionic concentrations were used to control the calcium phosphate surface layer thickness and prepare mineralized cross-linked PAA-b-PI micelles with variable shell permeability. The permeability of beta-carotene into the hydrophobic PI core of mineralized shell cross-linked PAA-b-PI micelles was reduced by approximately 50 or 100% respectively for hybrid nanostructures enclosed within 10 or 20 nm thick calcium phosphate layers. Our results suggest that calcium phosphate-polymer cross-linked nanocapsules could have potential applications as pH-responsive biocompatible hybrid nanostructures for use in applications such as drug delivery, bioimaging, and therapeutics.
authors.affiliation: Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
authors.forename: Kris K
authors.initials: KK
authors.lastname: Perkin
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Turner
authors.forename: Karen L
authors.initials: KL
authors.lastname: Wooley
authors.forename: Stephen
authors.initials: S
authors.lastname: Mann
mesh_terms: D001672:Biocompatible Materials / Q000032:analysis / Q000737:chemistry*; D002130:Calcium Phosphates / Q000032:analysis / Q000737:chemistry*; D003102:Colloids / Q000032:analysis / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D003460:Crystallization / Q000379:methods*; D046911:Macromolecular Substances / Q000032:analysis / Q000737:chemistry; D008422:Materials Testing; D008823:Micelles; D043942:Nanotubes / Q000032:analysis / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D010539:Permeability; D016062:Porosity; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; D003102:Colloids; D003432:Cross-Linking Reagents; D046911:Macromolecular Substances; D008823:Micelles; C519480:amorphous calcium phosphate; C020243:calcium phosphate