title: SiO2@Au core-shell nanospheres self-assemble to form colloidal crystals that can be sintered and surface modified to produce pH-controlled membranes.
abstract: We prepared colloidal crystals by self-assembly of gold-coated silica nanospheres, and free-standing nanoporous membranes by sintering these colloidal crystals. We modified the nanopore surface with ionizable functional groups, by forming a monolayer of L-cysteine or by surface-initiated polymerization of methacrylic acid. Diffusion experiments for the cationic dye Rhodamine B through L-cysteine-modified membranes showed a decrease in flux upon addition of an acid due to the nanopore surface becoming positively charged. Diffusion experiments for the neutral dye, ferrocenecarboxaldehyde, through the PMAA-modified membranes showed a 13-fold increase in flux upon addition of an acid resulting from the protonated polymer collapsing onto the nanopore surface leading to larger pore size. Our results demonstrate that SiO2@Au core-shell nanospheres can self-assemble into colloidal crystals and that transport through the corresponding surface-modified Au-coated colloidal membranes can be controlled by pH.
authors: Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA.
authors: Patricia Anne A
authors: PA
authors: Ignacio-de Leon
authors: Ilya
authors: I
authors: Zharov
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D000180:Acrylic Resins; D000327:Adsorption; D003102:Colloids; D003545:Cysteine / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D053768:Metal Nanoparticles / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D003102:Colloids; D008567:Membranes, Artificial; D011108:Polymers; C052970:poly-N-isopropylacrylamide; D011092:Polyethylene Glycols; D006046:Gold; D012822:Silicon Dioxide; D003545:Cysteine