Biomolecular Templates Research Articles

BIOMOLECULES CALL THE SHOTS

STRUCTURAL FEATURES OF biological molecules can be imprinted on inorganic crystals using a biomineralization procedure based on synthetic biomolecular templates [ J.Am. Chem. Soc, 125, 11786 (2003)].The technique, which was developed at the University of Illinois, Urbana- Champaign (UIUC), may lead to custom-designed crystals with useful electronic, magnetic, and optical properties. At the heart of the new crystalgrowth method are electrostatic forces that drive the material's synthesis steps. To prepare the templates, the UIUC researchers combine anionic DNA and cationic membranes that are composed of a mixture of lipids. The components self-assemble in solution, forming lamellar structures (stacks of sheets) in which DNA strands are confined between the lipid layers. The team, which includes assistant professor of materials science and physics Gerard C. L. Wong, Hongjun Liang, Paul V. Braun, and coworkers, notes that adding Cd 2+ ions to the solution causes the cations to assemble in the interhelical po...

Molecular Imprinting of Biomineralized CdS Nanostructures: Crystallographic Control Using Self-Assembled DNA−Membrane Templates

A wide range of biomineralization and templating methods exist for organizing inorganic materials at a wide range of length-scales. Here, we show that crystallographic control of the inorganic nanostructures is possible using synthetic biomolecular templates comprised of anionic DNA and cationic membranes, which self-assemble into a multilamellar structure where a periodic one-dimensional (1D) lattice of parallel DNA chains is confined between stacked two-dimensional (2D) lipid sheets. We have organized Cd2+ ions within the interhelical pores between DNA strands and subsequently reacted them with H2S to form CdS nanorods of controllable widths and crystallographic orientation. The strong electrostatic interactions align the templated CdS (002) polar planes parallel to the negatively charged sugar-phosphate DNA backbone, which indicates that molecular details of the DNA molecule are imprinted onto the inorganic crystal structure. The resultant nanorods have (002) planes tilted by 60 degrees with respect to the rod axis, in contrast to all known II-VI semiconductor nanorods.

Site-Specific Organization of Gold Nanoparticles by Biomolecular Templating

Site-Specific Organization of Gold Nanoparticles by Biomolecular Templating

Site-Specific Organization of Gold Nanoparticles by Biomolecular Templating

Site-Specific Organization of Gold Nanoparticles by Biomolecular Templating

Fabrication of highly oriented nanocluster arrays by biomolecular templating

The formation of highly oriented cluster arrays by chemical deposition of platinum onto a regular 2D protein template is studied. The crystalline bacterial surface layer (S layer) of Sporosarcina ureae exhibiting a p4 symmetry with a lattice spacing of 13.2 nm is used as the protein template. Cluster deposition onto the S layer is achieved by chemical reduction of a platinum salt. The growth kinetics of the clusters has been examined by UV–VIS spectrometry. Transmission electron microscopy reveals the formation of well separated metal clusters with an average diameter of 1.9±0.6 nm. The lateral cluster arrangement is defined by the underlying protein crystal. We observe 7 cluster sites per unit cell corresponding to a density of 4×1012 cm-2. They are located in the nano-sized pores and gaps of the crystalline S layer.

Three-dimensional metallization of microtubules

Microtubules (MTs), components of the cytoskeletons of eukaryotic cells, are protein filaments with outer diameters of 25 nm and lengths of several micrometers. Due to their large geometrical aspect ratios, they are well suited for use as biomolecular templates for the fabrication of magnetic and electrically conductive nanowires. Three-dimensional metallization of these MTs is demonstrated by an electroless deposition technique of nickel initiated by molecular palladium catalysts. In this study of the deposition conditions, it is shown that in the use of electroless plating for the metallization of tubulin assemblies the process parameters, such as temperature and pH, need to be adjusted to the chemical conditions of the in-vitro self-assembly process of MTs. The activated and metallized MTs have been characterized by scanning electron microscopy and transmission electron microscopy. Depending on the distribution of the Pd catalyst particles after MT activation, we found that a minimum nickel thickness of about 10 nm is required to produce a continuous film.

Nanopatterning by biological templating and laser direct writing in thin laser deposited films

We report on three alternative approaches to laser-supported sub-micro- and nanopatterning of ultrathin films. The inherent non-linearities of direct writing techniques can be used to fabricate structures far below the optical resolution limit. Due to the non-linear dependence of light absorption and reaction rate on film thickness and temperature (a) the lateral self-limitation of the oxidation reaction in ultrathin titanium films on a transparent heat insulating substrate in air can occur. The polarization of sharp conducting tips results in (b) near-field enhancement of the optical field in nanometer regions that allows diminishing of the effective size of the radiation source. The third approach (c) is based on the nanometer-period pattern transfer from a biomolecular template to a Pt/C overlayer deposited by cross-beam pulsed laser deposition.