Regular Arrangement of Gas Phase Prepared In-Flight Annealed FePt Nanoparticles on S Layers

Abstract

To achieve a regular quadratic particle arrangement, gas phase prepared FePt nanoparticles which were annealed in flight in order to obtain the highly anisotropic tetragonal 1 0 structure are deposited onto the regular 2-D bacterial surface-protein layer (S layer) of Bacillus sphaericus NCTC 9602 which exhibits a four-fold lattice symmetry with a lattice constant of 12.5 nm. The degree of regularity is studied by the statistical evaluation of the particles positions observed by transmission electron microscopy. Although the obtained regularity for the annealed hard magnetic particles is less than for previously studied disordered fcc FePt nanoparticles, a template-directed transfer of both lattice symmetry and periodicity from the 2-D protein crystal to the particle arrangement is observed. In addition, particle agglomeration which has been shown to have a strong effect on the arrangement's regularity, is clearly reduced for the annealed particles because of the mutual magnetic repulsion of adjacent particles.

Extraction and long‐term storage of S‐layer proteins and flagella from Lysinibacillus sphaericus NCTC 9602: Building blocks for nanotechnology

“…The respective SL coding gene has been cloned and the DNA as well as the amino acid sequence of the protein are known . The purified SL protein was extensively investigated as to the adsorption on various technical surfaces, use as molecularly defined metallization template (Pd, Pt) , decoration with gas‐phase prepared particles (FePt) , and integration into sensor devices . The studies exploited purified SL protein fractions that were obtained by different multistep extraction methods.…”

Catalytic Carbon Monoxide Oxidation Using Bio-Templated Platinum Clusters

“…Taking advantage of their spatially well-defined physical and chemical surface properties, S layers have extensively been used for the template-directed chemical synthesis of regular 2D semiconducting [7,8] and metallic [9][10][11][12][13][14] nanoparticle arrays. The specific property that their regular 2D structure is preserved under dry conditions [14] has recently allowed using S layers as templates for the organization of gasphase deposited FePt nanoparticles into 2D arrays [15][16][17]. In addition, the electronic structure of S layers has been investigated by photoemission and NEXAFS spectroscopy [18][19][20][21][22].…”