Selective Recognition of Fe(III) in Aqueous Environment over Covalently-Bonded Tb-Complex-Containing Fluorescent Porous Copolymer Microspheres

2018 ◽  
Vol 219 (24) ◽  
pp. 1800403
Author(s):  
Chunyan Zhang ◽  
Jianxin Luo ◽  
Wenjun Li ◽  
Lijuan Ou ◽  
Guipeng Yu ◽  
...  
Keyword(s):  
Selective Recognition ◽  
Aqueous Environment ◽  
Covalently Bonded ◽  
Porous Copolymer

Biomimetic Networks For Selective Recognition of Biomolecules

2002 ◽  
Vol 724 ◽  
Author(s):  
Mark E. Byrne ◽  
Kinam Park ◽  
Nicholas A. Peppas
Keyword(s):  
Confocal Microscopy ◽  
Fickian Diffusion ◽  
Polymerization Process ◽  
Selective Recognition ◽  
Template Molecule ◽  
Aqueous Environment ◽  
Macroporous Structure ◽  
Binding Studies ◽  
Specific Chemical ◽  
Aqueous Solvent

AbstractStudies of protein binding domains reveal molecular architectures with specific chemical moieties that provide a framework for selective recognition of target biomolecules in aqueous environment. By matching functionality and positioning of chemical residues, we have been successful in designing biomimetic polymer networks that specifically bind biomolecules in aqueous environments. Our work addresses the preparation, behavior, and dynamics of the three-dimensional structure of biomimetic polymers for selective recognition via non-covalent complexation. In particular, the synthesis and characterization of recognitive gels for the macromolecular recognition of D-glucose is highlighted. Novel copolymer networks containing poly(ethylene glycol) (PEG) and functional monomers such as acrylic acid, methacrylic acid, and acrylamide were synthesized in dimethyl sulfoxide (polar, aprotic solvent) via UV-free radical polymerization. Polymers were characterized by single and competitive equilibrium and kinetic binding studies, single and competitive fluorescent and confocal microscopy studies, dynamic network swelling studies, DPC, and FE-SEM. Results qualitatively and quantitatively demonstrate effective glucose-binding polymers in aqueous solvent. Due to the presence of template, the template mediated polymerization process resulted in a more macroporous structure as exhibited by dynamic swelling experiments, confocal microscopy, and SEM. Recognitive networks had a more macroporous structure with absorption of water occurring via non-fickian diffusion at a faster rate and with a higher equilibrium value. Polymerization kinetic studies suggest that the template molecule has more than a dilution effect on the polymerization, and the effect of the template is related strongly to the rate of propagation. The processes and analytical techniques presented are applicable to other biologically significant molecules and recognitive networks, in which hydrogen bonding, hydrophobic, or ionic contributions will direct recognition. Further developments are expected to have direct impact on applications such as analyte controlled and modulated drug and protein delivery, drug and biological elimination, drug targeting, tissue engineering, and micro- or nano-devices.

scholarly journals Covalent modification of single wall carbon nanotubes upon gamma irradiation in aqueous media

2011 ◽  
Vol 65 (5) ◽  
pp. 479-487 ◽  
Author(s):  
Svetlana Jovanovic ◽  
Zoran Markovic ◽  
Duska Kleut ◽  
Dragana Tosic ◽  
Dejan Kepic ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Gamma Irradiation ◽  
Structural Disorder ◽  
Single Wall Carbon Nanotubes ◽  
Aqueous Environment ◽  
Force Microscopy ◽  
Atomic Force ◽  
Covalently Bonded ◽  
Irradiation Treatment

Single wall carbon nanotubes (SWCNTs) were exposed to gamma radiation, absorbing the doses of 25, 50 and 100 kGy in aqueous environment. After the irradiation treatment, the changes in the structure were studied using Fourier Transform Infrared and Raman spectroscopy, thermogravimetric analysis and atomic force microscopy. Fourier Transform Infrared Spectroscopy has shown that the irradiation of SWCNTs in aqueous environment leads to covalent functionalization of SWCNTs. The irradiation of water leads to its radiolysis and the formation of free radical species of different types. These species react with nanotube sidewalls and in such way carboxylic and hydroxylic groups are covalently bonded to the sidewalls of SWCNTs. Thermogravimetric analysis was used to estimate the total amount of covalently bonded groups. The highest ratio of covalently bonded groups appears in nanotubes irradiated with the 100 kGy dose. Raman spectroscopy proves that the increase in irradiation doses leads to an increase of structural disorder of SWCNTs, presumably in the form of defects in carbon nanotube walls. Examination of ID to IG ratio shows a three times larger degree of structural disorder after the irradiation treatment with 100 kGy. The analysis of carbon nanotube Raman spectra RBM bands determined the presence of both semiconducting and metallic carbon nanotubes after gamma irradiation treatment. These measurements prove that gamma irradiation treatments have a nonselective effect regarding different chirality and therefore conductance of nanotubes. Atomic force microscopy shows a significant carbon nanotube shortening as the effect of gamma radiation treatment. Nanotubes with length between 500 nm and 1 ?m are predominant.

Morphological studies of linear (AB)n multiblock copolymers and their blends

1992 ◽  
Vol 50 (1) ◽  
pp. 384-385
Author(s):  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf
Keyword(s):  
Electron Microscopy ◽  
Microphase Separation ◽  
Multiblock Copolymers ◽  
First Order ◽  
Morphological Studies ◽  
Transmission Electron ◽  
First Order Phase Transition ◽  
Covalently Bonded ◽  
Total Molecular Weight ◽  
First Order Phase

Block copolymers are composed of sequences of dissimilar chemical moieties covalently bonded together. If the block lengths of each component are sufficiently long and the blocks are thermodynamically incompatible, these materials are capable of undergoing microphase separation, a weak first-order phase transition which results in the formation of an ordered microstructural network. Most efforts designed to elucidate the phase and configurational behavior in these copolymers have focused on the simple AB and ABA designs. Few studies have thus far targeted the perfectly-alternating multiblock (AB)n architecture. In this work, two series of neat (AB)n copolymers have been synthesized from styrene and isoprene monomers at a composition of 50 wt% polystyrene (PS). In Set I, the total molecular weight is held constant while the number of AB block pairs (n) is increased from one to four (which results in shorter blocks). Set II consists of materials in which the block lengths are held constant and n is varied again from one to four (which results in longer chains). Transmission electron microscopy (TEM) has been employed here to investigate the morphologies and phase behavior of these materials and their blends.

Morphological behavior of compatibilized ternary blends prepared by mechanical mixing

1993 ◽  
Vol 51 ◽  
pp. 1200-1201
Author(s):  
S.D. Smith ◽  
R.J. Spontak ◽  
D.H. Melik ◽  
S.M. Buehler ◽  
K.M. Kerr ◽  
...  
Keyword(s):  
Interfacial Adhesion ◽  
Diblock Copolymers ◽  
Ternary Blends ◽  
Mechanical Mixing ◽  
Design Considerations ◽  
Covalently Bonded ◽  
Homopolymer Blends ◽  
Emulsifying Agent ◽  
Surface Active ◽  
Low Entropy

When blended together, homopolymers A and B will normally macrophase-separate into relatively large (≫1 μm) A-rich and B-rich phases, between which exists poor interfacial adhesion, due to a low entropy of mixing. The size scale of phase separation in such a blend can be reduced, and the extent of interfacial A-B contact and entanglement enhanced, via addition of an emulsifying agent such as an AB diblock copolymer. Diblock copolymers consist of a long sequence of A monomers covalently bonded to a long sequence of B monomers. These materials are surface-active and decrease interfacial tension between immiscible phases much in the same way as do small-molecule surfactants. Previous studies have clearly demonstrated the utility of block copolymers in compatibilizing homopolymer blends and enhancing blend properties such as fracture toughness. It is now recognized that optimization of emulsified ternary blends relies upon design considerations such as sufficient block penetration into a macrophase (to avoid block slip) and prevention of a copolymer multilayer at the A-B interface (to avoid intralayer failure).

Prospects for scanned-probe microscopy

1994 ◽  
Vol 52 ◽  
pp. 6-7
Author(s):  
Jean-Paul Revel
Keyword(s):  
High Vacuum ◽  
Physiological Saline ◽  
Scanning Probe ◽  
Aqueous Environment ◽  
Whole Cells ◽  
Material Scientist ◽  
Biological Objects ◽  
Spatially Resolved ◽  
Atomic Force ◽  
Scanned Probe Microscopy

In the last 50+ years the electron microscope and allied instruments have led the way as means to acquire spatially resolved information about very small objects. For the material scientist and the biologist both, imaging using the information derived from the interaction of electrons with the objects of their concern, has had limitations. Material scientists have been handicapped by the fact that their samples are often too thick for penetration without using million volt instruments. Biologists have been handicapped both by the problem of contrast since most biological objects are composed of elements of low Z, and also by the requirement that sample be placed in high vacuum. Cells consist of 90% water, so elaborate precautions have to be taken to remove the water without losing the structure altogether. We are now poised to make another leap forwards because of the development of scanned probe microscopies, particularly the Atomic Force Microscope (AFM). The scanning probe instruments permit resolutions that electron microscopists still work very hard to achieve, if they have reached it yet. Probably the most interesting feature of the AFM technology, for the biologist in any case, is that it has opened the dream of high resolution in an aqueous environment. There are few restrictions on where the instrument can be used. AFMs can be made to work in high vacuum, allowing the material scientist to avoid contamination. The biologist can be made happy as well. The tips used for detection are made of silicon nitride,(Si3N4), and are essentially unaffected by exposure to physiological saline (about which more below). So here is an instrument which can look at living whole cells and at atoms as well.

Thermally-Induced Dehydrogenative Coupling of Organosilanes and H-Terminated Silicon Quantum Dots onto Germanane Surfaces

2020 ◽  
Author(s):  
Haoyang Yu ◽  
Alyxandra Thiessen ◽  
Md Asjad Hossain ◽  
Marc Julian Kloberg ◽  
Bernhard Rieger ◽  
...  
Keyword(s):  
2D Materials ◽  
Future Generation ◽  
Optical Devices ◽  
Surface Reactivity ◽  
Organic Monolayers ◽  
Present Contribution ◽  
Thermally Induced ◽  
Dehydrogenative Coupling ◽  
Silicon Quantum Dot ◽  
Covalently Bonded

<div><div><div><p>Covalently bonded organic monolayers play important roles in defining the solution processability, ambient stability, and electronic properties of two-dimensional (2D) materials such as Ge nanosheets (GeNSs); they also hold promise of providing avenues for the fabrication of future generation electronic and optical devices. Functionalization of GeNS normally involves surface moieties linked through covalent Ge−C bonds. In the present contribution we extend the scope of surface linkages to include Si−Ge bonding and present the first demonstration of heteronuclear dehydrocoupling of organosilanes to hydride-terminated GeNSs obtained from the deintercalation and exfoliation of CaGe2. We further exploit this new surface reactivity and demonstrated the preparation of directly bonded silicon quantum dot-Ge nanosheet hybrids.</p></div></div></div>

On the Adsorption of Aspartate Derivatives to Calcite Surfaces in Aqueous Environment

2020 ◽  
Author(s):  
Robert Stepic ◽  
Lara Jurković ◽  
Ksenia Klementyeva ◽  
Marko Ukrainczyk ◽  
Matija Gredičak ◽  
...  
Keyword(s):  
Active Sites ◽  
Realistic Model ◽  
Binding Energies ◽  
Inhibition Mechanism ◽  
Aqueous Environment ◽  
Binding Modes ◽  
Carboxylate Groups ◽  
Dissolved Ions ◽  
Living Organisms ◽  
Dynamics Simulations

In many living organisms, biomolecules interact favorably with various surfaces of calcium carbonate. In this work, we have considered the interactions of aspartate (Asp) derivatives, as models of complex biomolecules, with calcite. Using kinetic growth experiments, we have investigated the inhibition of calcite growth by Asp, Asp2 and Asp3.This entailed the determination of a step-pinning growth regime as well as the evaluation of the adsorption constants and binding free energies for the three species to calcite crystals. These latter values are compared to free energy profiles obtained from fully atomistic molecular dynamics simulations. When using a flat (104) calcite surface in the models, the measured trend of binding energies is poorly reproduced. However, a more realistic model comprised of a surface with an island containing edges and corners, yields binding energies that compare very well with experiments. Surprisingly, we find that most binding modes involve the positively charged, ammonium group. Moreover, while attachment of the negatively charged carboxylate groups is also frequently observed, it is always balanced by the aqueous solvation of an equal or greater number of carboxylates. These effects are observed on all calcite features including edges and corners, the latter being associated with dominant affinities to Asp derivatives. As these features are also precisely the active sites for crystal growth, the experimental and theoretical results point strongly to a growth inhibition mechanism whereby these sites become blocked, preventing further attachment of dissolved ions and halting further growth.

ИЗУЧЕНИЕ СТРУКТУРЫ ДНК В ПЛЕНКАХ МЕТОДОМ ИК-ФУРЬЕ-СПЕКТРОСКОПИИ

2020 ◽  
Vol 65 (6) ◽  
pp. 1058-1064
Author(s):  
С.В. Пастон ◽  
◽  
А.М. Поляничко ◽  
О.В. Шуленина ◽  
Д.Н. Осинникова ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Hydration Shell ◽  
Aqueous Environment ◽  
Ir Absorption ◽  
Sodium Ions ◽  
High Molecular Weight Dna ◽  
Dna Hydration ◽  
Na Ions ◽  
Phosphate Groups ◽  
Dna Film

The aqueous environment and ionic surrounding are the most important factors determining the conformation of DNA and its functioning in the cell. The specificity of the interaction between DNA and cations is especially pronounced with a decrease in water activity. In this work, we studied the B-A transition in high molecular weight DNA with a decrease of humidity in the film with different contents of Na+ ions using FTIR spectroscopy. The IR spectrum of DNA is not only very sensitive to the state of its secondary structure, but also allows us to estimate the amount of water bound to DNA. Upon dehydration of the DNA film, changes characteristic of the B-A transition were observed in the IR absorption spectrum. Using thermogravimetric analysis, it was shown that the degree of DNA hydration reaches the saturation level at a relative humidity of 60% and decreases slightly upon further drying. It has been established that with increasing Na+ concentration, the amount of water strongly bound to DNA decreases. Along with it, sodium ions destroy the hydration shell of DNA and are able to interact directly with phosphate groups.

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