title: Gold nanoparticle inclusion into protein nanotube as a layered wall component.
abstract: We describe the synthesis, structure, and catalytic activity of human serum albumin (HSA) nanotubes (NTs) including gold nanoparticles (AuNPs) as a layered wall component. The NTs were fabricated as an alternating layer-by-layer assembly of AuNP and HSA admixture (a negatively charged part) and poly-l-arginine (PLA, a positively charged part) into a track-etched polycarbonate membrane (400 nm pore diameter) with subsequent dissolution of the template. SEM images showed the formation of uniform hollow cylinders of (PLA/AuNP-HSA)3 with a 426 ± 12 nm outer diameter and 65 ± 7 nm wall thickness. Transmission electron microscopy and energy dispersive X-ray measurements revealed high loading of AuNPs in the tubular wall. HSAs bind strongly onto the individual AuNP (K = 1.25 × 10(9) M(-1)), generating a core-shell AuNP-HSA corona, which is the requirement of the robust NT formation. Calcination of the (PLA/AuNP-HSA)3 NTs at 500 °C under air yielded red solid NTs composed of thermally fused AuNPs. From the mass decrease by heat treatment, we calculated the weight of the organic components (PLA and HSA) and thereby constructed a six-layer model of the tube. The (PLA/AuNP-HSA)3 NTs serve as a heterogeneous catalyst for reduction of 4-nitrophenol with sodium borohydrate. Furthermore, implantation of the stiff (PLA/AuNP-HSA)3 NTs vertically onto glass plate produced uniformly cylindrical tube arrays.
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University , 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan.
authors.forename: Shun
authors.initials: S
authors.lastname: Goto
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Amano
authors.forename: Motofusa
authors.initials: M
authors.lastname: Akiyama
authors.forename: Christoph
authors.initials: C
authors.lastname: Böttcher
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Komatsu
mesh_terms: D002384:Catalysis; D006046:Gold / Q000737:chemistry*; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry; D012709:Serum Albumin / Q000737:chemistry*; D013696:Temperature
chemical_list: D010455:Peptides; D012709:Serum Albumin; C015462:polyarginine; D006046:Gold