Identification of Peptides That Promote the Rapid Precipitation of Germania Nanoparticle Networks Via Use of a Peptide Display Library

Chemical Communications (Cambridge, England). Aug, 2004  |  Pubmed ID: 15278181

Peptides that promote the rapid, room-temperature precipitation of amorphous germania nanoparticle networks from solution have been identified via use of a combinatorial peptide display library.

Bioenabled Synthesis of Rutile (TiO2) at Ambient Temperature and Neutral PH

Angewandte Chemie (International Ed. in English). Nov, 2006  |  Pubmed ID: 17009353

Rapid, Room-temperature Synthesis of Antibacterial Bionanocomposites of Lysozyme with Amorphous Silica or Titania

Small (Weinheim an Der Bergstrasse, Germany). May, 2006  |  Pubmed ID: 17193101

Chemical Reduction of Three-dimensional Silica Micro-assemblies into Microporous Silicon Replicas

Nature. Mar, 2007  |  Pubmed ID: 17344850

The carbothermal reduction of silica into silicon requires the use of temperatures well above the silicon melting point (> or =2,000 degrees C). Solid silicon has recently been generated directly from silica at much lower temperatures (< or =850 degrees C) via electrochemical reduction in molten salts. However, the silicon products of such electrochemical reduction did not retain the microscale morphology of the starting silica reactants. Here we demonstrate a low-temperature (650 degrees C) magnesiothermic reduction process for converting three-dimensional nanostructured silica micro-assemblies into microporous nanocrystalline silicon replicas. The intricate nanostructured silica microshells (frustules) of diatoms (unicellular algae) were converted into co-continuous, nanocrystalline mixtures of silicon and magnesia by reaction with magnesium gas. Selective magnesia dissolution then yielded an interconnected network of silicon nanocrystals that retained the starting three-dimensional frustule morphology. The silicon replicas possessed a high specific surface area (>500 m(2) g(-1)), and contained a significant population of micropores (< or =20 A). The silicon replicas were photoluminescent, and exhibited rapid changes in impedance upon exposure to gaseous nitric oxide (suggesting a possible application in microscale gas sensing). This process enables the syntheses of microporous nanocrystalline silicon micro-assemblies with multifarious three-dimensional shapes inherited from biological or synthetic silica templates for sensor, electronic, optical or biomedical applications.

Thin, Conformal, and Continuous SnO2 Coatings on Three-dimensional Biosilica Templates Through Hydroxy-group Amplification and Layer-by-layer Alkoxide Deposition

Angewandte Chemie (International Ed. in English). 2007  |  Pubmed ID: 17591742

Rapid Bioenabled Formation of Ferroelectric BaTiO3 at Room Temperature from an Aqueous Salt Solution at Near Neutral PH

Journal of the American Chemical Society. Jan, 2008  |  Pubmed ID: 18067293

A 12-mer peptide, identified through phage display biopanning, has been used for the first time to induce the rapid formation of ferroelectric (tetragonal) nanocrystalline BaTiO3 at room temperature from an aqueous salt precursor solution at near neutral pH. BaTiO3 is widely used in capacitors, thermistors, displays, and sensors owing to its attractive dielectric, ferroelectric, pyroelectric, optical, and electrochemical properties. Two 12-mer peptides (BT1 and BT2) were selected from a phage-displayed peptide library via binding to tetragonal BaTiO3 powder. While these peptides possessed various types of amino acids, 8 of the 12 amino acids were common to both peptides. Each of these peptides induced the formation of faceted nanoparticles (50-100 nm diameter) from an aqueous precursor solution. X-ray diffraction and selected area electron diffraction patterns obtained from these faceted nanoparticles were consistent with the BaTiO3 compound. Rietveld analyses of the X-ray diffraction patterns yielded good fits to tetragonal crystal structures, with the BaTiO3 formed in the presence of the BT2 peptide exhibiting the most tetragonal character. A coating of the latter BaTiO3 nanoparticles exhibited polarization hysteresis (a well-known characteristic of ferroelectric materials) at room temperature and a relative permittivity of 2200. Such rapid, peptide-induced precipitation at room temperature provides new opportunities for direct BaTiO3 formation on low-melting or reactive materials (e.g., plastics, cloths, bio-organics) and the low temperature integration of BaTiO3 into electronic devices (e.g., on silicon or flexible polymer substrates).

Protein- and Peptide-directed Syntheses of Inorganic Materials

Chemical Reviews. Nov, 2008  |  Pubmed ID: 18973389

Fluorescence Characterization of the Interaction Suwannee River Fulvic Acid with the Herbicide Dichlorprop (2-(2,4-dichlorophenoxy)propionic Acid) in the Absence and Presence of Aluminum or Erbium

Journal of Inorganic Biochemistry. Nov, 2011  |  Pubmed ID: 21983257

This study uses fluorescence spectroscopy to better understand the role of environmental metal ions in the interaction of charged herbicides with biochemical degradation product Suwannee River fulvic acid (SRFA). The interactions between the widely-used herbicide dichlorprop (2-(2,4-dichlorophenoxy)propionic acid) (DCPPA) with Al(3+) and the comparative metal Er(3+) were probed at pH 4.0. Fluorescence experiments on binary solutions at pH 4.0 clearly indicated that Al(3+) and Er(3+) strongly interact with both SRFA and DCPPA alone in solution as demonstrated by fluorescence quenching with DCPPA and enhancement with SRFA by Al(3+) and fluorescence quenching of both SRFA and DCPPA fluorescence by Er(3+). Titrating Al(3+) or Er(3+) to SRFA-DCPPA quenched SRFA fluorescence as compared to the SRFA-metal ion binary complexes. Formation constants were determined using the Ryan-Weber model for the titration data. The DCPPA fluorescence results strongly support the formation of DCPPA-Al(3+) and DCPPA-Er(3+) complexes at pH values above the pK(a) (3.0) of DCPPA. Excitation and emission data obtained on ternary solutions of SRFA-Al(3+)-DCPPA and SRFA-Er(3+)-DCPPA complexes at pH 4.0 suggest that at this pH where the predominant DCPPA species is negatively-charged, Al(3+) and Er(3+) metal ions may function to "bridge" negatively-charged fulvic acids to negatively-charged pesticides. Fluorescence data collected on UV-irradiated ternary complexes indicate that both metals can also bridge DCPPA interactions with SRFA under those conditions. The results of our studies suggest that creation of a herbicide-free boundary corridor is recommended near mines and runoff areas with metal ions in surface waters to control possible complexation among fulvic acids, DCPPA and metal ions that maintains these molecules in a bioavailable state to plants and animals.

Fibronectin Binding to the Treponema Pallidum Adhesin Protein Fragment RTp0483 on Functionalized Self-Assembled Monolayers

Bioconjugate Chemistry. Feb, 2012  |  Pubmed ID: 22175441

Past work has shown that Treponema pallidum, the causative agent of syphilis, binds host fibronectin (FN). FN and other host proteins are believed to bind to rare outer membrane proteins (OMPs) of T. pallidum, and it is postulated that this interaction may facilitate cell attachment and mask antigenic targets on the surface. This research seeks to prepare a surface capable of mimicking the FN binding ability of T. pallidum in order to investigate the impact of FN binding with adsorbed Tp0483 on the host response to the surface. By understanding this interaction, it may be possible to develop more effective treatments for infection and possibly mimic the stealth properties of the bacteria. Functionalized self-assembled monolayers (SAMs) on gold were used to investigate rTp0483 and FN adsorption. Using a quartz crystal microbalance (QCM), rTp0483 adsorption and subsequent FN adsorption onto rTp0483 were determined to be higher on negatively charged carboxylate-terminated self-assembled monolayers (-COO(-) SAMs) compared to the other surfaces analyzed. Kinetic analysis of rTp0483 adsorption using surface plasmon resonance (SPR) supported this finding. Kinetic analysis of FN adsorption using SPR revealed a multistep event, where the concentration of immobilized rTp0483 plays a role in FN binding. An examination of relative QCM dissipation energy compared to the shift in frequency showed a correlation between the physical properties of adsorbed rTp0483 and SAM surface chemistry. In addition, AFM images of rTp0483 on selected SAMs illustrated a preference of rTp0483 to bind as aggregates. Adsorption on -COO(-) SAMs was more uniform across the surface, which may help further explain why FN bound more strongly. rTp0483 antibody studies suggested the involvement of amino acids 274-289 and 316-333 in binding between rTp0483 to FN, while a peptide blocking study only showed inhibition of binding with amino acids 316-333. Finally, surface adsorbed rTp0483 with FN bound significantly less anti-RGD and gelatin compared to FN adsorbed directly to -COO(-) SAMs, indicating that one or both binding regions may play a role in binding between rTp0483 and FN.