scholarly journals Charge and Peptide Concentration as Determinants of the Hydrogel Internal Aqueous Environment

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 832 ◽  
Author(s):  
Scott Elgersma ◽  
Michelle Ha ◽  
Jung-Lynn Yang ◽  
Vladimir Michaelis ◽  
Larry Unsworth
Keyword(s):  
Water Content ◽  
Variable Temperature ◽  
Three Dimensional ◽  
Bound Water ◽  
Water Structure ◽  
Aqueous Environment ◽  
2H Nmr ◽  
Peptide Concentration ◽  
Self Assembling ◽  
Hydrogel Matrix

Self-assembling peptides are a promising class of biomaterials with desirable biocompatibility and versatility. In particular, the oligopeptide (RADA)4, consisting of arginine (R), alanine (A), and aspartic acid (D), self-assembles into nanofibers that develop into a three-dimensional hydrogel of up to 99.5% (w/v) water; yet, the organization of water within the hydrogel matrix is poorly understood. Importantly, peptide concentration and polarity are hypothesized to control the internal water structure. Using variable temperature deuterium solid-state nuclear magnetic resonance (2H NMR) spectroscopy, we measured the amount of bound water in (RADA)4-based hydrogels, quantified as the non-frozen water content. To investigate how peptide polarity affects water structure, five lysine (K) moieties were appended to (RADA)4 to generate (RADA)4K5. Hydrogels at 1 and 5% total peptide concentration were prepared from a 75:25 (w/w) blend of (RADA)4:(RADA)4K5 and similarly analyzed by 2H NMR. Interestingly, at 5% peptide concentration, there was lower mobile water content in the lysinated versus the pristine (RADA)4 hydrogel. Regardless of the presence of lysine, the 5% peptide concentration had higher non-frozen water content at temperatures as low as 217 ± 1.0 K, suggesting that bound water increases with peptide concentration. The bound water, though non-frozen, may be strongly bound to the charged lysine moiety to appear as immobilized water. Further understanding of the factors controlling water structure within hydrogels is important for tuning the transport properties of bioactive solutes in the hydrogel matrix when designing for biomedical applications.

scholarly journals Synchrotron radiation macromolecular crystallography: our science and spin offs

2014 ◽  
Vol 70 (a1) ◽  
pp. C10-C10
Author(s):  
John Helliwell
Keyword(s):  
Synchrotron Radiation ◽  
Protein Complexes ◽  
Bound Water ◽  
Water Structure ◽  
Public Understanding ◽  
Anomalous Scattering ◽  
Structural Studies ◽  
Macromolecular Crystallography ◽  
Time Resolved ◽  
Chemical Crystallography

I will give an overview of synchrotron radiation (SR) in macromolecular crystallography (MX) instrumentation, methods and applications from the early days to the present, including the evolution of SR sources and on to the `ultimate storage ring'. The build of dedicated beamlines for resonant anomalous scattering, large unit cells, ever smaller crystals and studies up to ultra-high resolution are core benefits. Results include a high output of PDB depositions, the successful use of microcrystals, pushing the frontiers of using high and low photon energies and time-resolved structural studies at even sub-nanosecond resolutions. These intensively physics based developments will be complemented by biological and chemical crystallography research results, encompassing catalysis and marine coloration, as well as the public understanding of our science and its impacts. Spin off benefits include services to the pharmaceutical industry and helping develop chemical crystallography uses of SR. The development of the Laue method with SR has led to pioneering spin off developments in neutron MX, including transfer of the well validated Daresbury Laue software to various neutron facilities worldwide. Neutron MX is gathering pace as new instrumentation and dedicated sample preparation facilities are in place at reactor and spallation neutron sources; smaller samples and much larger molecular weight protein complexes are now feasible for investigation so as to establish their protonation states and bound water structure. With the X-ray lasers, closely linked to the SR developments, we anticipate the use of ever smaller samples such as nanocrystals, nanoclusters and single molecules, as well as opening up femtosecond time-resolved diffraction structural studies. At the SR sources, a very high throughput assessment for the best crystal samples and tackling sub-micron crystals will become widespread.

scholarly journals Rapid discovery of self-assembling peptides with one-bead one-compound peptide library

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pei-Pei Yang ◽  
Yi-Jing Li ◽  
Yan Cao ◽  
Lu Zhang ◽  
Jia-Qi Wang ◽  
...  
Keyword(s):  
Combinatorial Library ◽  
Rapid Identification ◽  
Screening Strategy ◽  
Peptide Library ◽  
Aqueous Environment ◽  
Self Assembling ◽  
Material Sciences ◽  
The One ◽  
Combinatorial Space ◽  
Simple Screening

AbstractSelf-assembling peptides have shown tremendous potential in the fields of material sciences, nanoscience, and medicine. Because of the vast combinatorial space of even short peptides, identification of self-assembling sequences remains a challenge. Herein, we develop an experimental method to rapidly screen a huge array of peptide sequences for self-assembling property, using the one-bead one-compound (OBOC) combinatorial library method. In this approach, peptides on beads are N-terminally capped with nitro-1,2,3-benzoxadiazole, a hydrophobicity-sensitive fluorescence molecule. Beads displaying self-assembling peptides would fluoresce under aqueous environment. Using this approach, we identify eight pentapeptides, all of which are able to self-assemble into nanoparticles or nanofibers. Some of them are able to interact with and are taken up efficiently by HeLa cells. Intracellular distribution varied among these non-toxic peptidic nanoparticles. This simple screening strategy has enabled rapid identification of self-assembling peptides suitable for the development of nanostructures for various biomedical and material applications.

Three-Dimensional Hexagonal Close-Packed Superlattices of Passivated Ag Nanocrystals

1997 ◽  
Vol 3 (S2) ◽  
pp. 431-432
Author(s):  
S. A. Harfenist ◽  
Z. L. Wang ◽  
R. L. Whetten ◽  
I. Vezmar ◽  
M. M. Alvarez ◽  
...  
Keyword(s):  
Carbon Film ◽  
Three Dimensional ◽  
Structure Characterization ◽  
Self Assembled Monolayers ◽  
Hexagonal Close Packed ◽  
Self Assembling ◽  
Transmission Electron ◽  
Assembled Monolayers ◽  
High Resolution Tem ◽  
Nanocrystal Superlattices

Silver nanocrystals passivated by dodecanethiol self-assembled monolayers were produced using an aerosol technique described in detail elsewhere [1]. Self-assembling passivated nanocrystal-superlattices (NCS's) involve self-organization into monolayers, thin films, and superlattices of size-selected nanoclusters encapsulated in a protective compact coating [2,3,4,5,6,7]. We report the preparation and structure characterization of three-dimensional (3-D) hexagonal close-packed Ag nanocrystal supercrystals from Ag nanocrystals of ˜4.5 nm in diameters. The crystallography of the superlattice and atomic core lattices were determined using transmission electron microscopy (TEM) and high-resolution TEM.SEM was used to image the nanocrystal superlattices formed on an amorphous carbon film of an TEM specimen grid (fig. la). The superlattice films show well shaped, sharply faceted, triangular shaped sheets. Figure lb depicts numerous Ag nanocrystal aggregates uniformly distributed over the imaging region. Inset in this figure is an enlargement of the boxed region at the edge of a supercrystal typifying the ordered nanocrystal packing.

Ingan Quantum Dots Fabricated On Aigan Surfaces -Growth Mechanism And Optical Propertiesh-

1997 ◽  
Vol 482 ◽  
Author(s):  
H. Hirayama ◽  
S. Tanaka ◽  
P. Ramvall ◽  
Y. Aoyagi
Keyword(s):  
Quantum Dots ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Energy Shift ◽  
Organic Chemical ◽  
Self Assembling ◽  
Atomic Force ◽  
Peak Energy ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

AbstractWe demonstrate photoluminescence from self- assembling InGaN quantum dots (QDs), which are artificially fabricated on AlGaN surfaces via metal- organic chemical vapor deposition. InGaN QDs are successfully fabricated by the growth mode transition from step- flow to three dimensional island formation by using anti-surfactant silicon on AlGaN surface. The diameter and height of the fabricated InGaN QDs are estimated to be ˜10nm and ˜5nm, respectively, by an atomic- force- microscope (AFM). Indium mole fraction of InxGal−x N QDs is controlled from x=˜0.22 to ˜0.52 by varying the growth temperature of QDs. Intense photoluminescence is observed even at room temperature from InGaN QDs embedded with the GaN capping layers. In addition, the temperature- dependent energy shift of the photoluminescence peak- energy shows a localization behavior.

scholarly journals 3D Unsteady Diffusion and Reaction-Diffusion with Singularities by GFEM with 27-Node Hexahedrons

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Estaner Claro Romão
Keyword(s):  
Finite Element ◽  
Variable Temperature ◽  
Three Dimensional ◽  
Reaction Diffusion ◽  
Third Order ◽  
Order Of Accuracy ◽  
Finite Element Approximations ◽  
Temperature Solution ◽  
The One ◽  
Primary Variable

The Galerkin Finite Element Method (GFEM) with 8- and 27-node hexahedrons elements is used for solving diffusion and transient three-dimensional reaction-diffusion with singularities. Besides analyzing the results from the primary variable (temperature), the finite element approximations were used to find the derivative of the temperature in all three directions. This technique does not provide an order of accuracy compatible with the one found in the temperature solution; thereto, a calculation from the third order finite differences is proposed here, which provide the best results, as demonstrated by the first two applications proposed in this paper. Lastly, the presentation and the discussion of a real application with two cases of boundary conditions with singularities are proposed.

Capillary suction time (CST) as a measure of sludge dewaterability

1996 ◽  
Vol 34 (3-4) ◽  
pp. 443-448 ◽  
Author(s):  
G. W. Chen ◽  
W. W. Lin ◽  
D. J. Lee
Keyword(s):  
Water Content ◽  
Specific Resistance ◽  
Bound Water ◽  
The Other ◽  
Solid Concentration ◽  
Capillary Suction ◽  
Good Index ◽  
Other Hand ◽  
Sludge Dewaterability ◽  
Bound Water Content

The feasibility of employment of capillary suction time (CST) for characterizing the dewaterability of excess activated sludges was examined. The CST was shown as a good index for sludge filterability, if only the product of solid concentration and average specific resistance is of interest. On the other hand, the bound water content cannot be directly evaluated from the CST data.

scholarly journals Hydraulic Conductivity of Polymer-Amended Sand-Bentonite Backfills Permeated with Lead Nitrate Solutions

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Sheng-Qiang Shen ◽  
Ming-Li Wei
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Applied Pressure ◽  
Lead Nitrate ◽  
Bound Water ◽  
Liquid Limit ◽  
Filter Press ◽  
Diffuse Double Layer ◽  
Comparison Results ◽  
Pb Concentration

Hydraulic conductivity of sand-bentonite (SB) backfills amended with polyanionic cellulose (PAC) to lead nitrate (Pb(NO3)2) solutions was evaluated experimentally in this study. PAC-amended sand-bentonite (PSB) backfills were synthesized by mixing sand-bentonite mixture with 0.3 to 1.2% dry PAC (by total dry mixture mass) and mixed with a certain weight of conventional bentonite (CB) slurry. The rheology properties including the filtrate loss, viscosity, density, and pH testes of slurry with various bentonite dosages were measured to determine the reasonable CB dosage of slurry. The slump tests on PSB backfills with various mass slurries were conducted to determine the corresponding water content of backfills with slump 125 ± 5 mm. Under the applied pressure 100 kPa, the hydraulic conductivity to Pb(NO3)2 solutions (kc) of PSB backfills with various PAC contents was evaluated based on the modified filter press (MFP) tests, to ascertain the optimum PAC content of PSB backfills when permeated with Pb(NO3)2 solutions. Index properties, including the specific gravity (Gs) and liquid limit (wL) of PSB backfills, were measured after MFP tests. The MFP tests for PSB backfills were then conducted under various applied pressures to obtain the relationship between void ratio (e) and hydraulic conductivity of backfills. Finally, the flexible-wall permeability test (FWP test) under osmotic pressure 100 kPa was conducted to verify the effectiveness of the MFP test. The results indicate that slurry with 8% bentonite dosage is the reasonable choice in slurry wall construction. PSB has lower GS and higher wL compared to SB; increasing Pb concentration leads to GS of PSB increased and wL of PSB decreased. PSB with 0.6% PAC content is supposed as the optimum proportion of backfills when permeated with concentrated Pb(NO3)2 solution. PAC adsorbs large amount of bound water, which leads to higher water content (w) and e of PSB backfills, while lead ions (Pb) cause the diffuse double layer (DDL) of bentonite compressed and e of PSB backfills reduced. The kc of PSB-0.6 remains lower than 10−9 m/s and increases less than 10 times though the Pb concentration was up to 500 mM, demonstrating that the hydraulic performance of backfills can be improved effectively in Pb(NO3)2 solution by the additive PAC. The comparison results between k from MFP tests and FWP tests show that the MFP test is an effective and easy evaluation of hydraulic conductivity of backfills.

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