scholarly journals Cyclodextrin Polymers and Cyclodextrin-Containing Polysaccharides for Water Remediation

2021 ◽  
Vol 2 (1) ◽  
pp. 16-38
Author(s):  
Tânia F. Cova ◽  
Dina Murtinho ◽  
Roberto Aguado ◽  
Alberto A. C. C. Pais ◽  
Artur J. M. Valente
Keyword(s):  
Aqueous Media ◽  
Three Dimensional ◽  
Water Soluble ◽  
Water Remediation ◽  
Dimensional Structure ◽  
Chemical Pollution ◽  
Hydroxyl Groups ◽  
Interaction Patterns ◽  
Polycarboxylic Acids ◽  
Sorbent Materials

Chemical pollution of water has raised great concerns among citizens, lawmakers, and nearly all manufacturing industries. As the legislation addressing liquid effluents becomes more stringent, water companies are increasingly scrutinized for their environmental performance. In this context, emergent contaminants represent a major challenge, and the remediation of water bodies and wastewater demands alternative sorbent materials. One of the most promising adsorbing materials for micropolluted water environments involves cyclodextrin (CD) polymers and cyclodextrin-containing polysaccharides. Although cyclodextrins are water-soluble and, thus, unusable as adsorbents in aqueous media, they can be feasibly polymerized by using different crosslinkers such as epichlorohydrin, polycarboxylic acids, and glutaraldehyde. Likewise, with those coupling agents or after substituting hydroxyl groups with more reactive moieties, cyclodextrin units can be covalently attached to a pre-existing polysaccharide. In this direction, the functionalization of chitosan, cellulose, carboxymethyl cellulose, and other carbohydrate polymers with CDs is vastly found in the literature. For the system containing CDs to be used for remediation purposes, there are benefits from a synergy that arises from (i) the ability of CD units to interact selectively with a broad spectrum of molecules, forming inclusion complexes and higher-order supramolecular assemblies, (ii) the functional groups of the crosslinker comonomers, (iii) the three-dimensional structure of the crosslinked network, and/or (iv) the intrinsic characteristics of the polysaccharide backbone. In view of the most recent contributions regarding CD-based copolymers and CD-containing polysaccharides, this review discusses their performance as adsorbents in micropolluted water environments, as well as their interaction patterns, addressing the influence of their structural and physicochemical properties and their functionalization.

scholarly journals Anchoring Water Soluble Phosphotungstic Acid by Hybrid Fillers to Construct Three-Dimensional Proton Transport Networks

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 536
Author(s):  
Shaojian He ◽  
Zhongrui Lu ◽  
Wenxu Dai ◽  
Kangning Yang ◽  
Yang Xue ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Composite Membrane ◽  
Proton Transport ◽  
Phosphotungstic Acid ◽  
Three Dimensional ◽  
Water Soluble ◽  
Hydroxyl Groups ◽  
Transport Networks ◽  
Hybrid Fillers ◽  
Speek Membrane

Phosphotungstic acid (HPW)-filled composite proton exchange membranes possess high proton conductivity under low relative humidity (RH). However, the leaching of HPW limits their wide application. Herein, we propose a novel approach for anchoring water soluble phosphotungstic acid (HPW) by polydopamine (PDA) coated graphene oxide and halloysite nanotubes (DGO and DHNTs) in order to construct hybrid three-dimensional proton transport networks in a sulfonated poly(ether ether ketone) (SPEEK) membrane. The introduction of PDA on the surfaces of the hybrid fillers could provide hydroxyl groups and secondary amine groups to anchor HPW, resulting in the uniform dispersion of HPW in the SPEEK matrix. The SPEEK/DGO/DHNTs/HPW (90/5/5/60) composite membrane exhibited higher water uptake and much better conductivity than the SPEEK membrane at low relative humidity. The best conductivity reached wass 0.062 S cm−1 for the composite membrane, which is quite stable during the water immersion test.

scholarly journals Effects of ionizing radiations on proteins. Evidence of non-random fragmentations and a caution in the use of the method for determination of molecular mass

1990 ◽  
Vol 267 (2) ◽  
pp. 431-439 ◽  
Author(s):  
M Le Maire ◽  
L Thauvette ◽  
B de Foresta ◽  
A Viel ◽  
G Beauregard ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Molecular Mass ◽  
Three Dimensional ◽  
Water Soluble ◽  
Dimensional Structure ◽  
Intact Protein ◽  
Aspartate Transcarbamylase ◽  
Ionizing Radiations ◽  
Polypeptide Chains ◽  
Best Fit

We have reinvestigated the use of ionizing radiations to measure the molecular mass of water-soluble or membrane proteins. The test was performed by using the most straightforward aspect of the technique, which consists of SDS/PAGE analysis of the protein-fragmentation process. We found that exposure of purified standard proteins to increasing doses of ionizing radiation causes progressive fragmentation of the native protein into defined peptide patterns. The coloured band corresponding to the intact protein was measured on the SDS gel as a function of dose to determine the dose (D37.t) corresponding to 37% of the initial amount of unfragmented protein deposited on the gel. This led to a calibration curve between 1/D37.t and the known molecular mass of the standard proteins whose best fit gave Mr = 1.77 x 10(6)/D37.t at -78 degrees C, i.e. 35% higher than the generally accepted value at that temperature obtained from inactivation studies. However, we have to conclude that this method is useless to determine the state of aggregation of a protein, since, for all the oligomers tested, the best fit was obtained by using the protomeric molecular mass, suggesting that there is no energy transfer between promoters. Furthermore, SDS greatly increases the fragmentation rate of proteins, which suggests additional calibration problems for membrane proteins in detergent or in the lipid bilayer. But the main drawback of the technique arises from our observation that some proteins behaved anomalously, leading to very large errors in the apparent target size as compared with true molecular mass (up to 100%). It is thus unreliable to apply the radiation method for absolute molecular-mass determination. We then focused on the novel finding that discrete fragmentation of proteins occurs at preferential sites, and this was studied in more detail with aspartate transcarbamylase. N-Terminal sequencing of several radiolysis fragments of the catalytic chain of the enzyme revealed that breaks along the polypeptide chains are localized close to the C-terminal end. Examination of the three-dimensional structure of aspartate transcarbamylase suggests that radiolysis sites (fragile bonds) might be localized in connecting loops.

scholarly journals MECHANICAL CHARACTERISTICS FOR COMPOSITE MATERIALS USING COMMERCIAL EPOXY RESINS AND DIFFERENT FILLERS

2021 ◽  
Vol 56 (5) ◽  
pp. 179-185
Author(s):  
Omar A. Amin ◽  
S. A. Hassan ◽  
M. A. Sadek ◽  
M. A. Radwan ◽  
Hany A. Elazab
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Epoxy Resins ◽  
Three Dimensional ◽  
Mechanical Tests ◽  
Diglycidyl Ether ◽  
Dimensional Structure ◽  
Polymeric Chain ◽  
Hydroxyl Groups ◽  
Different Types

Epoxy resins are thermoset polymers that consist of epoxide groups in their molecular structure. It shows many attractive characteristics like strong adhesion, excellent mechanical strength, low shrinkage, excellent insulator, excellent chemical stability for acidic and basic environments, and microbial resistance due to the presence of hydroxyl groups and ether bonds and its three-dimensional structure. Many of these characteristics can be modified by adding strong bindings in the polymeric chain to give more improved characteristics. This research aims to prepare a composite material using epoxy resin and different types of fillers to achieve resistance to high kinetic energy impact. Experimental work is focused on preparing cured epoxy resin samples by using diglycidyl ether of bisphenol A (DGEBA) resin with tertiary amine as a hardener. In order to obtain different samples with different properties, we add different types of fillers, then mechanical tests are used to measure the mechanical properties of the samples. The results have proved that fiberglass is the best filler added to epoxy resins to improve its mechanical properties.

scholarly journals X-Ray Diffraction of Magnetically Oriented Microcrystals of Protein

2014 ◽  
Vol 70 (a1) ◽  
pp. C349-C349
Author(s):  
Shu Tsukui ◽  
Fumiko Kimura ◽  
Kimihiko Mizutani ◽  
Bunzo Mikami ◽  
Tsunehisa Kimura
Keyword(s):  
Single Crystal ◽  
Three Dimensional ◽  
Water Soluble ◽  
Dimensional Structure ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Consolidation Process ◽  
X Ray ◽  
Three Dimensional Structure

Elucidation of the three-dimensional structure of biomolecules is of great importance because the three-dimensional structure is closely related to biological functions. X-ray single-crystal analysis is powerful method to analyze the structure, but it is sometimes difficult to grow a crystal sufficiently large for conventional or even synchrotron single-crystal X-ray measurement. We recently reported on a magnetically oriented microcrystal array (MOMA) [1] that is a composite in which microcrystals are aligned three-dimensionally in polymer matrix. Microcrystals are suspended in an ultraviolet-curable monomer and rotated non-uniformly in a static magnetic field to achieve three dimensional crystal alignment. Then, the monomer is photopolymerized to maintain the achieved alignment. We have successfully demonstrated that X-ray single crystal structure determinations through MOMA are possible for low molecular weight compounds [2] as well as protein. [3] However, the method with MOMA has two drawbacks: (i) the sample microcrystals cannot be recovered from a MOMA, which is especially serious problem in case of proteins, and (ii) the alignment is deteriorated during the consolidation process, causing low resolution. In this study, we attempt to solve these problems. First, we use a water-soluble sol as microcrystalline media and consolidate the alignment by gelation, which makes the recovery of microcrystals possible. Second, a magnetically oriented microcrystal suspension (MOMS) is used for in-situ X-ray diffraction measurement, which makes the sample recovery possible and enhances the resolution. We use lysozyme as a model protein for both cases. The in-situ method with in-house X-ray diffractometer gave diffraction spots about 3.0 Å resolutions. We plan to perform the same experiment at SPring-8.

scholarly journals Three-Dimensional Structure of Different Functional Forms of the Vibrio cholerae Hemolysin Oligomer: a Cryo-Electron Microscopic Study

2009 ◽  
Vol 192 (1) ◽  
pp. 169-178 ◽  
Author(s):  
Somnath Dutta ◽  
Budhaditya Mazumdar ◽  
Kalyan K. Banerjee ◽  
Amar N. Ghosh
Keyword(s):  
Vibrio Cholerae ◽  
Three Dimensional ◽  
Water Soluble ◽  
Particle Methods ◽  
Dimensional Structure ◽  
Striking Difference ◽  
Electron Microscopic ◽  
Membrane Bilayer ◽  
Lectin Domain ◽  
Structural Differences

ABSTRACT Vibrio cholerae hemolysin (HlyA) is a 65-kDa water-soluble pore-forming toxin that causes lysis of eukaryotic cells by destroying selective permeability of the plasma membrane bilayer. The HlyA monomer self-assembles on the target cell surface to the more stable β-barrel amphipathic heptamer, which inserts into the membrane bilayer to form a diffusion channel. Deletion of the 15-kDa β-prism lectin domain at the C terminus generates a 50-kDa hemolysin variant (HlyA50) with an ∼1,000-fold decrease in hemolytic activity. Because functional differences are eventually dictated by structural differences, we determined three-dimensional structures of 65- and 50-kDa HlyA oligomers, using cryo-electron microscopy and single-particle methods. Our study clearly shows that the HlyA oligomer has sevenfold symmetry but that the HlyA50 oligomer is an asymmetric molecule. The HlyA oligomer has bowl-like, arm-like, and ring-like domains. The bowl-like domain is coupled with the ring-like domain, and seven side openings are present just beneath the ring-like domain. Although a central channel is present in both HlyA and HlyA50 oligomers, they differ in pore size as well as in shape of the molecules and channel. These structural differences may be relevant to the striking difference in efficiencies of functional channel formation by the two toxin forms.

scholarly journals IMMOBILIZATION OF COBALT DISULFOPHTHALOCYANINATE ONTO POLYMETHYLOLACRYLAMIDE

2018 ◽  
Vol 61 (8) ◽  
pp. 73
Author(s):  
Galina V. Osipova ◽  
Nadezhda L. Pechnikova ◽  
Tatiana A. Ageeva
Keyword(s):  
Metal Complex ◽  
Water Solubility ◽  
Electronic Absorption Spectra ◽  
Aqueous Media ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Water Soluble ◽  
Water Soluble Polymer ◽  
One Step ◽  
Insoluble Compounds

Different character of usage the porphyrins and their analogs immobilized on carrier polymers stimulates an increased interest in the synthesis and research of physico-chemical properties of porphyrin-polymer immobilizates. In this paper the peculiarities of a synthesis of water-soluble polymer systems containing cobalt disulfophthalocyaninate with the components of a different ratio are described. The methylolation reaction of polyacrylamide to immobilize cobalt disulfophthalocyaninate onto water-soluble carrier polymer has been carried out. It is known that heating polymethylolacrylamide or its solutions leads to the formation of three-dimensional structures with ether and methylene bridges. Therefore, initially the conditions for the preparation of polymethylolacrylamide with preservation of its water solubility were selected. It was found to obtain a water-soluble polymethylolacrylamide, it is necessary that the initial concentration of polyacrylamide in water did not exceed 2% by weight. The immobilization of phthalocyanine metal complex onto the modified polyacrylamide was carried out in two ways. The first is the interaction of the phthalocyanine metal complex with methylated polyacrylamide. The second is functionalization of polyacrylamide and the immobilization of phthalocyaninate metal complex onto the polymer in one-step. The introduction conditions of the cobalt disulfophthalocyaninate introduced influenced the formation of cross-linked structures in the synthesized samples. The introduction of macroheterocycle as a powder was found to promote the formation of insoluble compounds in aqueous media. Therefore, phthalocyanine metal complex was introduced into the system as 1% aqueous solution. The immobilization of the phthalocyanine metal complex onto a carrier polymer has been realized through the formation of hydrogen bonds between the methylol groups of polymethylolacrylamide and sulfo groups of the phthalocyanine metal complex and it was due to coordination interaction between the functional groups of the polymer and metallophthalocyanine as well. The amount of bound cobalt disulfophthalocyanine in the samples was determined by the electronic absorption spectra of the solutions of immobilized phthalocyanine metal complex onto the polymer. The mass content of immobilized cobalt disulfophthalocyaninate onto the polymer in the samples obtained by one-step is greater than in case of the samples obtained in two steps, the ratio of the initial reagents being the same.

scholarly journals Hydrogels as Controlled Drug Delivery System: A Brief Review of Properties Classification and Synthesis

2020 ◽  
Vol V (I) ◽  
pp. 40-49
Author(s):  
Hina Shoukat ◽  
Sobia Noreen ◽  
Saima Asghar
Keyword(s):  
Drug Delivery ◽  
Three Dimensional ◽  
Water Soluble ◽  
Dimensional Structure ◽  
Polymeric Network ◽  
System A ◽  
Controlled Drug Delivery System ◽  
Swelling Mechanism ◽  
Regenerative Medicines ◽  
Novel Drug

Hyrogels are cariers of novel drug delievry system and these polymeric network have ability to hold large amount of water but they do not dissolve in water .These polymeric network may be crosslinked either through chemical or physical crosslinking method. Without changing their three dimensional structure hydrogels undergo the swelling mechanism Hydrogels are used as drug delivery carriers because of their distinctive properties. They have three dimensional configurations and have water soluble cross linked network of polymers .Hydrogels have porous structure and by changing the cross linker concentration we can modify their affinity for water. Because of their unique properties these are used for various medical purposes like cellular immobilization , tissue engineering ,diagnostics and regenerative medicines.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

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