Ordered silica mineralization by regulating local reaction conditions

2018 ◽  
Vol 6 (9) ◽  
pp. 2316-2319 ◽  
Author(s):  
Takaaki Hatanaka ◽  
Masataka Ohashi ◽  
Nobuhiro Ishida
Keyword(s):  
Local Reaction ◽  
Cationic Peptides ◽  
Reaction Conditions ◽  
Physiological Conditions

Using cationic peptides with tetramethyl orthosilicate, a silica nano-film >100 μm in size with <100 nm thickness was constructed under physiological conditions.

Dynamic modeling of local reaction conditions in an agitated aerobic fermenter

AIChE Journal ◽  
2006 ◽  
Vol 52 (5) ◽  
pp. 1673-1689 ◽  
Author(s):  
Marko Laakkonen ◽  
Pasi Moilanen ◽  
Ville Alopaeus ◽  
Juhani Aittamaa
Keyword(s):  
Dynamic Modeling ◽  
Local Reaction ◽  
Reaction Conditions

scholarly journals Development of A Flexible Cell Targeting System Based on Silica Nanoparticles

1998 ◽  
Vol 530 ◽  
Author(s):  
T. Schiimstel ◽  
H. Schirra ◽  
J. Gerwann ◽  
C. Lesniak ◽  
A. Kalaghi-Nafchi ◽  
...  
Keyword(s):  
Silica Nanoparticles ◽  
Electrostatic Interactions ◽  
Particle Concentration ◽  
Biological Function ◽  
Particle Surface ◽  
Cell Types ◽  
Silica Particles ◽  
Hydrodynamic Diameter ◽  
Reaction Conditions ◽  
Physiological Conditions

AbstractCommercially available and synthesized silica particles were fluorescently labeled with FITC and modified to get a wide variety of particle systems with defined size and surface charge. By a variation of reaction conditions particles with diameters of 10 and 80 nm determined with TEM and with zetapotentials between -50 to +30 mV under physiological conditions (pH: 7.4, PBS-buffer) were available.A further molecular shell consisiting of avidin was obtained by binding the molecules to negatively charged particle surfaces through electrostatic interactions. The amount of avidin coupled to the silica particles was 1.7 μg per mg particle. Starting with particles with an hydrodynamic diameter determined with PCS of 260 nm, the size increased to 500 nm, while the zeta potential was altered to -8 mV under physiological conditions.Biotinylated wheat germ agglutinin (bio-WGA) can be bonded to such particles through avidin / biotin complex formation. Up to 2.8 μg lectin per mg particles could be coupled to the particle surface. This leads to a further increase of hydrodynamic diameter to 650 nm. It could be shown by hemagglutination test, that the bonded lectin is still active. No toxic effects of the silica particles were found at 1 wt.-% particle concentration with various cell types (Caco-2, L132). The binding of lectin-particle complexes to cells was increased by a factor of 4.4 in comparison to uncoated particles.In addition it was found that WGA can directly be coupled to the particle surface. An amount of 1.8 μg Lectin per mg particle was determined. The hydrodynamic diameter increases from 260 nm to 432 rm, while a zetapotential of-28 mV was found under physiological conditions.It could be shown, that negatively charged silica nanoparticles are suitable systems to couple various biomolecules retaining their biological function.

scholarly journals Fibrin gels and their clinical and bioengineering applications

2008 ◽  
Vol 6 (30) ◽  
pp. 1-10 ◽  
Author(s):  
Paul A Janmey ◽  
Jessamine P Winer ◽  
John W Weisel
Keyword(s):  
Mechanical Properties ◽  
Wound Healing ◽  
Cell Migration ◽  
Network Architecture ◽  
Blood Clotting ◽  
Reaction Conditions ◽  
Fibrin Gels ◽  
Physiological Conditions ◽  
Small Strains ◽  
Fibrin Network

Fibrin gels, prepared from fibrinogen and thrombin, the key proteins involved in blood clotting, were among the first biomaterials used to prevent bleeding and promote wound healing. The unique polymerization mechanism of fibrin, which allows control of gelation times and network architecture by variation in reaction conditions, allows formation of a wide array of soft substrates under physiological conditions. Fibrin gels have been extensively studied rheologically in part because their nonlinear elasticity, characterized by soft compliance at small strains and impressive stiffening to resist larger deformations, appears essential for their function as haemostatic plugs and as matrices for cell migration and wound healing. The filaments forming a fibrin network are among the softest in nature, allowing them to deform to large extents and stiffen but not break. The biochemical and mechanical properties of fibrin have recently been exploited in numerous studies that suggest its potential for applications in medicine and bioengineering.

Biolabeling with cobaltocinium tags

2018 ◽  
Vol 73 (11) ◽  
pp. 781-791
Author(s):  
Susanne Müller-Bomke ◽  
Michael Sperling ◽  
Heiko Hayen ◽  
Uwe Karst
Keyword(s):  
Liquid Chromatography ◽  
Redox Potential ◽  
Chemical Stability ◽  
Spectroscopic Properties ◽  
Mass Spectrometric ◽  
Mass Spectrometric Detection ◽  
Cysteine Residues ◽  
Reaction Conditions ◽  
Physiological Conditions ◽  
Derivatizing Agent

AbstractA label for amino and thiol functionalities of peptides and proteins based on the activated cobaltocinium hexafluorophosphate succinimide ester (CoS) is presented. Despite the known selectivity of a succinimide ester towards amines, CoS also modifies cysteine residues under the same reaction conditions. The derivatized biomolecules were investigated using liquid chromatography with subsequent electrospray-mass spectrometric detection (LC/ESI-MS). In combination with their remarkable stability under physiological conditions, easy handling and good spectroscopic properties, cobaltocinium ions provide all requirements for a powerful labeling reagent. Furthermore, in direct comparison to the isoelectronic well-established ferrocene reagents, the higher redox potential and the chemical stability of the cobaltocinium moiety add to the benefits as a derivatizing agent for bioanalysis.

Local Reaction Probability Effects in Non-Classical Kinetics: Batch and Steady State

1992 ◽  
Vol 290 ◽  
Author(s):  
Zhong-You Shi ◽  
Raoul Kopelman
Keyword(s):  
Steady State ◽  
Nearest Neighbor ◽  
Local Reaction ◽  
Reaction Order ◽  
Reaction Probability ◽  
Neighbor Distance ◽  
Reaction Conditions ◽  
Diffusion Limited ◽  
Diffusion Limited Reaction ◽  
Effective Reaction

AbstractThe reaction A+A→0 is simulated in 1-D and 2-D square lattices with various local reaction probabilities, P. The effective reaction order, X, and the nearest neighbor distance distribution (NNDD), are evaluated in all these reactions. For batch reactions, sharp increases in X with increasing P occur at early times. Classical reaction limited kinetics is obtained at early times only when P→0. At long times, all reactions are in the non-classical, diffusion limited regime, regardless of P. For steady state reactions, our results demonstrate a similar behavior of X with P. The NNDD at steady state in 1-D media at P=1.0, i.e. diffusion limited reaction, follows the previously reported skewed exponential shape. This is no longer true for P<I. Finally, at P→0, as expected, an exponential (Poissonian) distribution is obtained for both reaction conditions.

scholarly journals A Search for Structural Alternatives of RNA

2019 ◽  
Vol 53 (1) ◽  
Author(s):  
Ramanarayanan Krishnamurthy
Keyword(s):  
Nucleic Acids ◽  
Base Pairing ◽  
Reaction Conditions ◽  
Physiological Conditions ◽  
Pairing Strength ◽  
First Approximation ◽  
Recognition Elements ◽  
The Difference ◽  
Direct Outcome ◽  
The Relationship

This account describes a search for potentially primordial informational oligomers; the work is the direct outcome of the research program that was initiated by the Eschenmoser group —at ETH Zürich about 20 years ago and was continued at The Scripps Research Institute since 1996— in order to understand the chemical basis on which nucleic acids were chosen by nature as the molecular foundation of its genetic apparatus. The investigation began with the study of the base-pairing properties of structural alternatives of nucleic acids —constructed from different sugars (hexo- & pentopyranoses and tetrofuranose) retaining the canonical nucleobases and phosphates. The outcome from these studies led to the conclusion that Watson-Crick type base-pairing is not unique to RNA/DNA, and that it can be compatible with a wide variety of backbone edifice. This provided the motivation to map the landscape of potentially primordial informational oligomer systems that may contain backbones, recognition elements and linker groups structurally quite different from those known so far. The oligomer systems chosen for study are, conceptually, deemed to be (a) potentially primordial (based on the nature of the starting materials and reaction conditions considered to be prebiotically realistic) and (b) informational (based on their ability to adopt a repetitive conformation such that the information encoded by the recognition elements can be transmitted intermolecularly). Though such studies suggest the possibility of finding informational systems that could lay claim as functional ancestors of RNA —they are more likely to generate results that provide the opportunity to assess the structural and functional uniqueness of nature’s choice. The experimental investigation described here deals with the base-pairing properties of oligomer systems derived from 2,4-disubsituted -triazines, -5-aminopyrimdines and -6-carboxy pyrimidines as recognition elements that are tagged to oligo-dipeptide backbones via different linker groups. The results from the inter- and intra-system cross-pairing studies reveal that there is, on first approximation, a direct correlation between the magnitude of the difference in DpKa of the recognition elements and their base-pairing strength —smaller the Dpka between the base-pairing partners, weaker is the base-pairing strength (in aqueous medium at near neutral pH). These results exemplify the inherent singularity of the canonical nucleobases— their ability to remain un-ionized under physiological conditions based on their constitution – emphasizing the relationship between their physicochemical properties and their functional competence in connection with their role in informational base-pairing.

Horseradish peroxidase-catalyzed hydrogelation for biomedical applications

2018 ◽  
Vol 6 (6) ◽  
pp. 1286-1298 ◽  
Author(s):  
Mehdi Khanmohammadi ◽  
Mahsa Borzouyan Dastjerdi ◽  
Arman Ai ◽  
Akbar Ahmadi ◽  
Arash Godarzi ◽  
...  
Keyword(s):  
Horseradish Peroxidase ◽  
Biomedical Applications ◽  
Water Soluble ◽  
Biocompatible Polymers ◽  
Reaction Conditions ◽  
Physiological Conditions ◽  
Gelation Rate

Hydrogels catalyzed by horseradish peroxidase (HRP) serve as an efficient and effective platform for biomedical applications due to their mild reaction conditions for cells, fast and adjustable gelation rate in physiological conditions, and an abundance of substrates as water-soluble biocompatible polymers.

Ultrastructure of Giant Mitochondria and Their Inclusions in Schwann Cells of Bovine Splenic Nerve

1974 ◽  
Vol 32 ◽  
pp. 194-195
Author(s):  
Å. Thureson-Klein
Keyword(s):  
Schwann Cells ◽  
Cell Organelles ◽  
Giant Mitochondria ◽  
Matrix Density ◽  
Physiological Conditions ◽  
Unmyelinated Axons ◽  
Internal Structures ◽  
Structural Abnormalities ◽  
Cytotoxic Compounds ◽  
Cell Components

Giant mitochondria of various shapes and with different internal structures and matrix density have been observed in a great number of tissues including nerves. In most instances, the presence of giant mitochondria has been associated with a known disease or with abnormal physiological conditions such as anoxia or exposure to cytotoxic compounds. In these cases degenerative changes occurred in other cell organelles and, therefore the giant mitochondria also were believed to be induced structural abnormalities.Schwann cells ensheating unmyelinated axons of bovine splenic nerve regularly contain giant mitochondria in addition to the conventional smaller type (Fig. 1). These nerves come from healthy inspected animals presumed not to have been exposed to noxious agents. As there are no drastic changes in the small mitochondria and because other cell components also appear reasonably well preserved, it is believed that the giant mitochondria are normally present jin vivo and have not formed as a post-mortem artifact.

Undecagold labeling of tRNA

1991 ◽  
Vol 49 ◽  
pp. 44-45
Author(s):  
James F. Hainfeld ◽  
Kyra M. Alford ◽  
Mathias Sprinzl ◽  
Valsan Mandiyan ◽  
Santa J. Tumminia ◽  
...  
Keyword(s):  
High Resolution ◽  
Transmission Electron Micrograph ◽  
Anticodon Loop ◽  
Electron Micrograph ◽  
Reaction Conditions ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

The undecagold (Au11) cluster was used to covalently label tRNA molecules at two specific ribonucleotides, one at position 75, and one at position 32 near the anticodon loop. Two different Au11 derivatives were used, one with a monomaleimide and one with a monoiodacetamide to effect efficient reactions.The first tRNA labeled was yeast tRNAphe which had a 2-thiocytidine (s2C) enzymatically introduced at position 75. This was found to react with the iodoacetamide-Aun derivative (Fig. 1) but not the maleimide-Aun (Fig. 2). Reaction conditions were 37° for 16 hours. Addition of dimethylformamide (DMF) up to 70% made no improvement in the labeling yield. A high resolution scanning transmission electron micrograph (STEM) taken using the darkfield elastically scattered electrons is shown in Fig. 3.

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