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Functionalized bionanoparticles: Grafting chemistry and self-assembly
Naturally occurring horse spleen ferritin (HSF) bionanoparticles (BNPs) (12 nm in diameter) with magnetic cores (8 nm in diameter) are distinct from synthetic nanoparticles due to their perfectly defined size and shape, and abundant amino acid surface functionality. The theme of this thesis is the use of HSF BNPs as nanoscale building blocks for surface functionalization and directed assembly. Bioconjugation grafting chemistry was utilized to tailor the surface properties of HSF BNPs, and interfacial assembly techniques were applied to control the ordering of BNPs and integrate the functionalized BNPs into composite materials. By taking advantage of surface available amines on the exterior surface of ferritin BNPs, norbornene functionalities were attached by amidation of an N-hydrosuccimide (NHS)-functionalized norbornene. Norbornene functionalized ferritin BNPs were co-assembled with norbornene-functionalized CdSe/ZnS quantum dots at an oil/water interface to form robust, ultra-thin films and capsules upon crosslinking by means of ring-opening metathesis polymerization (ROMP). Ordered hexagonal arrays of gold nanodots on a silica substrate were prepared by block copolymer micelle lithography. PEGylated alkane thiols attached to ferritin BNPs enabled a specific interaction of BNPs with the gold nanodots through a thiol-gold linkage. As a result of the guided assembly of ferritin BNPs on the gold nanodots, highly ordered ferritin BNP arrays were achieved over a large area, and confirmed by grazing incidence small angle X-ray scattering (GISAXS). Grafting chemistry was performed to grow poly(methacryloyloxyethyl phosphorylcholine) (polyMPC), and poly(PEG methacrylate) (polyPEGMA), chains from the surface of ferritin BNPs using atom transfer radical polymerization (ATRP). The resulting hydrophilic polymer coatings were found to have a distinct impact on the recognition properties of the ferritin BNPs, as seen in their suppressed interactions with thin film polymer templates, and their resistance to antibody recognition. The solubility of polyPEGMA-coated ferritin nanoparticles in organic solvents enables their dissolution in the block copolymer polystyrene-b-poly (ethylene oxide) (PS-b-PEO), and selective integration into the PEO domains of microphase-separated copolymer nanostructures by self-assembly. This approach provides yet another interfacial assembly strategy to control the spatial distribution of polymer-grafted ferritin BNPs.
Hu, Yunxia, "Functionalized bionanoparticles: Grafting chemistry and self-assembly" (2011). Doctoral Dissertations Available from Proquest. AAI3445162.