Self-assembly of dendrimer-encapsulated nanoparticle arrays using 2-D microbial S-layer protein biotemplates.
We investigated the formation of self-assembled two-dimensional (2-D) arrays of dendrimer-encapsulated platinum nanoparticles (Pt-DENs) using prokaryotic surface-layer (S-layer) proteins as biomacromolecular templates. The Pt-DENs (mean core diameter 1.8 +/- 0.5 nm) were synthesized by chemical reduction of metal ion species complexed within the interior of fourth-generation, hydroxyl-terminated, starburst poly(amidoamine) dendrimers (G4 PAMAM-OH). Detailed structural and elemental composition analyses performed using high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy indicated that the dendrimer-metal nanocomposite particles were crystalline in nature rather than amorphous and that at least some quantity of the platinum found within the particles is present in the expected zerovalent state. By using the S-layer lattices from the acidothermophilic archaeon Sulfolobus acidocaldarius and the Gram-positive bacterium Deinococcus radiodurans as a biotemplate, hexagonal- and honeycomb-ordered arrays of the Pt-DENs were successfully fabricated under a range of different pH conditions via noncovalent nanoparticle-protein interactions. Fast Fourier transform analyses of transmission electron microscopy images verified that the fabricated Pt-DEN assemblies displayed mean periodicities that corresponded well with the lattice constants of the native protein templates (i.e., 22 and 18 nm for S. acidocaldarius and D. radiodurans S layers, respectively). Our results demonstrate that utilizing pre-synthesized Pt-DENs in conjunction with microbial S-layer proteins displaying highly periodic topochemical properties can be an effective, novel route for creating patterned arrays of Pt nanoparticles with potential technological applications.
Mark
Sonny S
SS
Department of Microbiology, Cornell University, Ithaca, New York 14853, USA. ssm12@cornell.edu
Bergkvist
Magnus
M
Yang
Xin
X
Angert
Esther R
ER
Batt
Carl A
CA
D000327:Adsorption; D019843:Archaeal Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002214:Capsules / Q000138:chemical synthesis* / Q000737:chemistry; D002478:Cells, Cultured; D050091:Dendrimers / Q000138:chemical synthesis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D010984:Platinum / Q000737:chemistry*; D013045:Species Specificity; D016945:Sulfolobus acidocaldarius / Q000737:chemistry / Q000254:growth & development; D013499:Surface Properties
D019843:Archaeal Proteins; D002214:Capsules; D050091:Dendrimers; D010984:Platinum