Formation of Nanoparticle Arrays on S-Layer Protein Lattices
Crystalline bacterial cell surface layers (S-layers) composed of identical protein units have been used as binding templates for well-organized arrangements of nanoparticles. Isolated S-layer proteins were
recrystallized into monomolecular arrays on solid substrates (such as silicon wafers and SiO2-coated grids) and in suspension forming so-called self-assembly products. These S-layer assemblies
were studied by atomic force microscopy and transmission electron microscopy (TEM). The orientation of the S-layer lattice, exhibiting anisotropic surface properties, on the solid surface and on the self-assembly
products, was compared with the orientation on the bacterial cell. On both bacterial cells and SiO2 surfaces the outer face of the S-layer protein was exposed. On the self-assembly products occasionally
the inner face was also visible. Metal- and semiconductor nanoparticles 2 to 10 nm in mean diameter were covalently or electrostatically bound to the solid-supported S-layers and self-assembly products.
TEM studies reveal that upon activation of carboxyl groups in the S-layer lattice with 1-ethyl-3,3′(dimethylaminopropyl)carbodiimide (EDC), a close-packed monolayer of 4-nm amino-functionalized
CdSe nanoparticles could be covalently established on the S-layer lattice. Because of electrostatic interactions, anionic citrate-stabilized Au nanoparticles (5 nm in diameter) formed a superlattice at
those sites where the inner face of the S-layer lattice was exposed. In contrast, cationic semiconductor nanoparticles (such as amino-functionalized CdSe particles) formed arrays on the outer face of the
solid-supported S-layer lattices.
Keywords: ARRAY; CRYSTALLINE S-LAYERS; NANOPARTICLE; PROTEIN; SUPERLATTICE
Document Type: Research Article
Publication date: 01 January 2004
- Journal for Nanoscience and Nanotechnology (JNN) is an international and multidisciplinary peer-reviewed journal with a wide-ranging coverage, consolidating research activities in all areas of nanoscience and nanotechnology into a single and unique reference source. JNN is the first cross-disciplinary journal to publish original full research articles, rapid communications of important new scientific and technological findings, timely state-of-the-art reviews with author's photo and short biography, and current research news encompassing the fundamental and applied research in all disciplines of science, engineering and medicine.
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