Department of Chemical EngineeringAll nanomaterials exhibit large surface to volume ratio in common and their surfaces have great influence with physicochemical properties of them. Therefore, surface engineering of nanomaterials is key to the utilization of unique nanomaterials properties and flexible strategies for deign of advanced materials. In this respect, catechol based nanocoating have been significantly attracted for application of nanocrystals and functionalization of substrates because of its adaptability to universal surface and high affinity in harsh condition. This dissertation demonstrates fabrication and characterization of nanocoating through amine mediated redox modulation of catechol. Synthetic mechanism of the nanocoating was suggested and surface engineering of metal oxide nanoparticles by the coating method have been studied. In addition, compact, biocompatible, and charge modulated iron oxide nanoparticles were synthesized and its bio-application was reported.
First, conformal nanocoatings to nanostructured materials was achieved through amine-mediated redox control of a catechol system by separating catechol and amine, which effectively suppress cohesion and enhance a adhesion to yield an optimized nanocoating. The amine-assisted catechol nanocoating exhibits roughness of <0.358 nm and thickness of 1.69 nm on flat substratesthe hydrodynamic diameter of coated iron oxide nanoparticles is less than 20 nm. Surface characterization, density functional theory calculations, and effect of separated amine were investigated to elucidate the coating mechanism. Three key roles of separated amine in the catechol-based nanocoating were suggested as follows, adhesion promotion, suppression of polymerization, and additional stabilization through an in-situ generated, newly designed catechol-amine adduct.
Second, multidentate catechol based polyethylene glycol random copolymer ligands was synthesized by reverse addition and fragmentation transfer polymerization. Compact, biocompatible and colloidal stable iron oxide nanoparticles have been synthesized by the ligands via the amine assisted catechol nanocoating method and applied into in vivo magnetic resonance contrast agents. High resolution magnetic resonance angiography with long circulation time was reported.
Finally, charge modulated metal oxide nanoparticles were synthesized by surface engineering with multidentate catechol based polymeric ligands. The charged iron oxide nanoparticles exhibit different behavior in vitro cell experiments and gene delivery into cell by positive charged nanoparticles was demonstrated.clos
