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Title: Mesostructure from Hydration Gradients in Demosponge Biosilica

; ; ; ;  [1];  [2]
  1. (CSU)
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chem.-Eur. J.; Journal Volume: 20; Journal Issue: (17) ; 04, 2014
Country of Publication:
United States

Citation Formats

Neilson, James R., George, Nathan C., Murr, Meredith M., Seshadri, Ram, Morse, Daniel E., and UCSB). Mesostructure from Hydration Gradients in Demosponge Biosilica. United States: N. p., 2014. Web. doi:10.1002/chem.201304704.
Neilson, James R., George, Nathan C., Murr, Meredith M., Seshadri, Ram, Morse, Daniel E., & UCSB). Mesostructure from Hydration Gradients in Demosponge Biosilica. United States. doi:10.1002/chem.201304704.
Neilson, James R., George, Nathan C., Murr, Meredith M., Seshadri, Ram, Morse, Daniel E., and UCSB). Mon . "Mesostructure from Hydration Gradients in Demosponge Biosilica". United States. doi:10.1002/chem.201304704.
title = {Mesostructure from Hydration Gradients in Demosponge Biosilica},
author = {Neilson, James R. and George, Nathan C. and Murr, Meredith M. and Seshadri, Ram and Morse, Daniel E. and UCSB)},
abstractNote = {},
doi = {10.1002/chem.201304704},
journal = {Chem.-Eur. J.},
number = (17) ; 04, 2014,
volume = 20,
place = {United States},
year = {Mon Jul 21 00:00:00 EDT 2014},
month = {Mon Jul 21 00:00:00 EDT 2014}
  • Future materials are envisioned to include bio-assembled, hybrid, three-dimensional nanosystems that incorporate functional proteins. Diatoms are amenable to genetic modification that enables localization of recombinant proteins in the biosilica cell wall. Our objective was to functionalize diatom biosilica with a reagent-less biosensor with FRET-based imaging capabilities for signaling. The design of the fusion protein conferring these properties included a bacterial periplasmic ribose binding protein (R) flanked by CyPet (C) and YPet (Y), cyan and yellow fluorescent proteins that act as a FRET pair. The structure and function of the recombinant chimeric protein was first confirmed in E. coli-expressed proteins, priormore » to transformation of the diatom Thalassiosira pseudonana. Mass spectrometry of CRY showed 95% identity with the deduced amino acid sequence. CRY with and without an N-terminal Sil3 tag for biosilica targeting exhibited characteristic ribose-dependent changes in FRET, with similar dissociation constants of 123.3 {mu}M and 142.8 {mu}M, respectively. The addition of the silaffin tag for biosilica localization did not influence the affinity of CRY for the ribose substrate. Subsequent transformation of T. pseudonana with a vector encoding Sil3-CRY resulted in fluorescence localization in the biosilica and changes in FRET in both living cells and isolated biosilica in response to ribose. This work demonstrated that the nano-architecture of the genetically modified biosilica cell wall was able to support the functionality of the relatively complex Sil3-CyPet-RBP-YPet fusion protein with its requirement for ligand binding and conformational change for FRET-signal generation.« less
  • The diatom Thalassiosira pseudonana was genetically modified to express biosilica-targeted fusion proteins incorporating a tetracysteine tag for site-directed labeling with biarsenical affinity probes and either EGFP or single chain antibody to test colocalization of probes with the EGFP-tagged recombinant protein or binding of biosilica-immobilized antibodies to large and small molecule antigens, respectively. Site-directed labeling with the biarsenical probes demonstrated colocalization with EGFP-encoded proteins in nascent and mature biosilica, supporting their use in studying biosilica maturation. Isolated biosilica transformed with a single chain antibody against either the Bacillus anthracis surface layer protein EA1 or small molecule explosive trinitrotoluene (TNT) effectively boundmore » the respective antigens. A marked increase in fluorescence lifetime of the TNT surrogate Alexa Fluor 555-trinitrobenzene reflected the high binding specificity of the transformed isolated biosilica. These results demonstrated the potential use of biosilica-immobilized single chain antibodies as binders for large and small molecule antigens in sensing and therapeutics.« less
  • In this paper we studied the photoinduced electro optics effects in the thermal transformation process of biosilica to cristobalite, at a relatively low temperature and ambient pressure. This process was characterized by a variety of standards techniques with emphasis on linear electro optic effect measurements. Overall we demonstrated that photoinduced electro optics measurements are very sensitive to the transformation from amorphous structure of silica in the natural sponge samples to laminar string morphology of cristobalite. With this technique we could probe the change in the samples chirality from achiral bio silica to chiral cristobalite structure. Furthermore it is shown thatmore » natural biosilica have photoinduced linear electro optics respond indicating the chiral natural of biosilica. - Graphical abstract: The phase transformation of biosilica from marine sponges to Cristobalite under thermal treatment was investigated using photoinduced electro optics measurements. The figure shows the changes of the electro-optic coefficient of cristobalite and biosilica. - Highlights: • We examine phase transformation of biosilica. • We report transition from amorphous biosilica to crystalline Cristobalite. • Biosilica transformation to Cristobalite at temperature of 850 °C. • Biosilica transformation is studied with photoinduced measurements. • We examine changes in the photoinduced linear electro optics properties.« less
  • Electron paramagnetic resonance (EPR) has now become firmly established as one of the methods of choice for analyzing the carbon network over a range of different volume fraction of the carbon black in the composite, i.e., below and above the respective conduction threshold concentration. In the present article, two types of carbon blacks, having very different primary structures, surface areas, and percolation thresholds, were used; Raven 7000 (of high surface area and high percolation threshold volume fraction) and Y50A (of low surface area and low percolation threshold volume fraction). A semiquantitative image analysis of the microstructure from transmission electron microscopymore » reveals information about the spatial distribution of the carbon aggregates and agglomerates inside the composite. We observe that the apparent surface of agglomerates increases significantly with increasing carbon black content for the two types of blacks investigated. Adsorbed oxygen on the carbon black cristallites and dynamic coalescence under mixing conditions can be responsible for the broadening of the dispersed phase surface distribution. The interagglomerate distance in two samples of concentrations f{lt}f{sub c} and f{congruent}f{sub c} of Raven 7000 are nearly identical indicating that the dc condition threshold can therefore be almost entirely attributed to the coalescence of smaller aggregates. Line shape simulation showed that the changes in the absorption EPR spectra, at temperatures between 105 and 300 K, of the composite samples containing Raven 7000 can be described by a linear superposition of two distinct Lorentzian (one broad and the other narrow) resonance lines and a single (narrow) Lorentzian resonance line for composite samples containing Y50A. The spins giving rise to the EPR signal reside in the carbon black particles. In Raven 7000, the significant difference in linewidth between the two signals demonstrates a different environment where the restriction of the motion of the paramagnetic centers varies. The narrower line was assigned to spin probes with high mobility (carbon black aggregates) and the broad one to probes with restricted mobility incorporated in carbon black agglomerates. In Y50A, only the sites with high mobility were detected. When the temperature is increased the data demonstrate that the EPR signal intensity, which is the double integral in arbitrary units divided by the mass of the carbon black contained in the sample, decreases slowly in the temperature range 105{endash}300 K. The various phenomena observed are attributed mainly to the aggregates and agglomerates structure in the composite samples. The temperature dependence of the paramagnetic susceptibility deduced from the EPR integrated intensity is discussed in terms of Adriaanse {close_quote}s model [L. J. Adriaanse, J. A. Reedijk, P. A. A. Teunissen, H. B. Brom, M. A. J. Michels, and J. C. M. Brokken-Zijp, Phys. Rev. Lett. 78, 1755 (1997)]. The magnetic susceptibility of the composite samples is also measured with a superconducting quantum interference device magnetometer, operating at an applied magnetic field of 0.5 T, from 2 K to room temperature. The observed temperature dependence of the spin susceptibility is discussed and suggests that morphology heterogeneity is of overwhelming importance to understand the magnetic properties of these materials. {copyright} 2001 American Institute of Physics.« less