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Covalently cross linked

Münteha Nur Sonuç Karaboğa, Mustafa Kemal Sezgintürk
This paper illustrates a new and sensitive electrochemical immunosensor for the analysis of C-reactive protein. Indium Tin Oxide (ITO) disposable sheets were modified by using 3-cyanopropyltrimethoxysilane (CPTMS) self-assembled monolayers (SAMs) for the first time for immobilizing the anti-CRP antibody via covalent interactions without the need for any cross-linking agent. Cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), as well as square wave voltammetry (SWV) methods were applied to characterize immobilization steps of anti-CRP and to determine the CRP concentration...
March 12, 2018: Journal of Pharmaceutical and Biomedical Analysis
Tianfu Wei, Zhengyi Chen, Gongke Li, Zhuomin Zhang
Aflatoxins are highly toxic mycotoxin contamination, which pose serious food safety incidents. It is very important to precisely and rapidly determine trace aflatoxins in food. In this study, we designed porous monolithic column based on covalent cross-linked polymer gels for online extraction and analysis of trace aflatoxins in food samples with complicated matrices coupled with high-performance liquid chromatography-ultraviolet detector (HPLC-UV). The prepared monolithic column showed excellent enrichment performance due to its good permeability, good reproducibility and long life span...
March 12, 2018: Journal of Chromatography. A
Nicole Welsch, Ashley C Brown, Thomas H Barker, L Andrew Lyon
Excessive bleeding and resulting complications are a major cause of death in both trauma and surgical settings. Recently, there have been a number of investigations into the design of synthetic hemostatic agents with platelet-mimicking activity to effectively treat patients suffering from severe hemorrhage. We developed platelet-like particles from microgels composed of polymers carrying polyethylene glycol (PEG) side-chains and fibrin-targeting single domain variable fragment antibodies (PEG-PLPs). Comparable to natural platelets, PEG-PLPs were found to enhance the fibrin network formation in vitro through strong adhesion to the emerging fibrin clot and physical, non-covalent cross-linking of nascent fibrin fibers...
March 2, 2018: Colloids and Surfaces. B, Biointerfaces
Aurelio Vazquez de la Torre, Marina Gay, Sílvia Vilaprinyó-Pascual, Roberta Mazzucato, Montserrat Serra-Batiste, Marta Vilaseca, Natalia Carulla
Brain-derived amyloid-β (Aβ) dimers are associated with Alzheimer´s disease (AD). However, their covalent nature remains controversial. This feature is relevant, as a covalent cross-link would make brain-derived dimers (brain dimers) more synaptotoxic than Aβ monomers and would make them suitable candidates for biomarker development. To resolve this controversy, we here present a three-step approach. First, we validated a type of synthetic cross-linked Aβ (CL Aβ) dimers, obtained by means of the photo-induced cross-linking of unmodified proteins (PICUP) reaction, as well-defined mimics of putative brain CL Aβ dimers...
March 14, 2018: Analytical Chemistry
Zhijun Chen, Xiaoliang Wang, Yang Liu, Jiao Liu
Protein-polymer microcapsules attracted much attention due to their special feature and potential in biological use. How to make the most of this type of bio-abiotic hybrid material is an intriguing question. Nevertheless, several unsatisfactory technical issues significantly limited the application of these materials. For instance, introducing various biomolecules and cross-linking for the capsules remain challenging and problematic. In this report, recombinant mCherry protein was covalently linked with PNIPAAm to form amphiphilic protein-polymer conjugates, assembled into microcapsules...
March 14, 2018: Chembiochem: a European Journal of Chemical Biology
Orestis G Andriotis, Sylvia Desissaire, Philipp J Thurner
Tissue hydration is well known to influence tissue mechanics and can be tuned via osmotic pressure. Collagen fibrils are nature's nanoscale building blocks to achieve biomechanical function in a broad range of biological tissues and across many species. Intrafibrillar covalent cross-links have long been thought to play pivotal role for collagen fibril elasticity, but predominantly at large, far from physiological, strains. Performing nanotensile experiments of collagen fibrils at varying hydration levels by adjusting osmotic pressure in situ during atomic force microscopy experiments, we show the power the intrafibrillar non-covalent interactions have for defining collagen fibril tensile elasticity at low fibril strains...
March 12, 2018: ACS Nano
Guangfa Zhang, Qinghua Zhang, Tiantian Cheng, Xiaoli Zhan, Fengqiu Chen
High durability, low cost, and superior anti-icing and active de-icing multifunctional surface coatings, espeicially in the extreme environment, are highly desired to inhibit and/or eliminate the detriment of icing in many fields, such as automobile, aerospace, and power transmission. Herein, we first report a facile and versatile strategy to prepare novel slippery polyols-infused porous surfaces (SPIPSs) with the inexpensive polyols as the lubricant liquids. These SPIPSs are fabricated by a spray-coating approach based on amino-modified magnetic Fe3O4 nanoparticles (MNP@NH2) and amphiphilic P(Poly(ethylene glycol) methyl ether methacrylate-co-glycidyl methacrylate)) copolymer (P(PEGMA-co-GMA) ) covalent cross-linked hybrids, followed by infusion with various polyols...
March 12, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Kuppan Gokulan, Sangeeta Khare, Carl E Cerniglia, Steven L Foley, Kottayil I Varughese
The final step of peptidoglycan (PG) synthesis in all bacteria is the formation of cross-linkage between PG-stems. The cross-linking between amino acids in different PG chains gives the peptidoglycan cell wall a 3-dimensional structure and adds strength and rigidity to it. There are two distinct types of cross-linkages in bacterial cell walls. D,D-transpeptidase (D,D-TPs) generate the classical 4➔3 cross-linkages and the L,D-transpeptidase (L,D-TPs) generate the 3➔3 non-classical peptide cross-linkages...
March 9, 2018: AAPS Journal
Hiroki Sawada, Masamichi Yamanaka
The successful development of stiff supramolecular gels is an important goal toward their practical application. One approach to stiffen supramolecular gels is to introduce covalent cross-link. The bis-urea dimer 2, having a structure similar to that of the low-molecular-weight gelator 1, was synthesized. Supramolecular hydrogels were formed from mixtures of 1 and 2 in appropriate ratios, with 2 acting as a covalent cross-linker to connect the fibrous aggregates formed by the self-assembly of 1. The introduction of these covalent cross-links greatly influenced the dynamic viscoelasticity of the supramolecular hydrogels...
March 7, 2018: Chemistry, An Asian Journal
Marta Ruiz-Santaquiteria, Sonia de Castro, Miguel A Toro, Héctor de Lucio, Kilian Jesús Gutiérrez, Pedro A Sánchez-Murcia, María Ángeles Jiménez, Federico Gago, Antonio Jiménez-Ruiz, María-José Camarasa, Sonsoles Velázquez
Trypanothione reductase (TryR) is a well-established target in the search for novel antitrypanosomal and antileishmanial agents. We have previously identified linear and lactam-bridged 13-residue peptides derived from an α-helical region making up part of the dimeric interface of Leishmania infantum TryR (Li-TryR) which prevent trypanothione reduction by disrupting enzyme dimerization. We now show that i,i + 4 side-chain cross-linking with an all-hydrocarbon staple stabilizes the helical structure of these peptides and significantly improves their resistance to protease cleavage relative to previous linear and cyclic lactam analogues...
February 24, 2018: European Journal of Medicinal Chemistry
Xinran Xiang, Hongbo Suo, Chao Xu, Yi Hu
Chitosan-mesoporous silica SBA-15 hybrid nanomaterials (CTS-SBA-15) were synthesized by means of carboxyl functionalized ionic liquids as the coupling agent. The as-prepared CTS-SBA-15 support was characterized by TEM, FTIR, TG and nitrogen adsorption-desorption techniques. Porcine pancreas lipase (PPL) was then bound to the hybrid nanomaterials by using the cross-linking reagent glutaraldehyde (GA). Further, the parameters like cross-linking concentration, time and ratio of supports to enzyme were optimized...
February 21, 2018: Colloids and Surfaces. B, Biointerfaces
Victor L Davidson
A protein-derived cofactor is a catalytic or redox-active site in a protein that is formed by post-translational modification of one or more amino acid residues. These post-translational modifications are irreversible and endow the modified amino acid residues with new functional properties. This Perspective focusses on the following advances in this area that have occurred during recent years. The biosynthesis of the tryptophan tryptophylquinone (TTQ) cofactor is catalyzed by a di-heme enzyme, MauG. A bis-FeIV redox state of the hemes performs three two-electron oxidations of specific Trp residues via long-range electron transfer...
March 2, 2018: Biochemistry
Juan Wang, Geoffrey S Williamson, Hu Yang
In this work, we developed a new class of branched polyrotaxane hydrogel made of 4-arm polyethylene glycol (4-PEG) and α-cyclodextrin (α-CD) using supramolecular host-guest interactions as a cross-linking strategy. Because of the dynamic nature of the non-covalent host-guest cross-linking, the resulting supramolecular α-CD/4-PEG hydrogels show thixotropic behavior and undergo a reversible gel-sol transition in response to shear stress change. We loaded the antiglaucoma drug brimonidine into the α-CD/4-PEG gel and found the drug release kinetics was controlled by shear stress...
February 15, 2018: Colloids and Surfaces. B, Biointerfaces
Károly Baintner
The first 60-min phase of inflammatory ascites formation was studied by intraperitoneally (i.p.) administered macromolecular inducers: yeast cell wall zymosan binds to specific macrophage receptors, polyethyleneimine (PEI) and concanavalin A (ConA), produces non-covalent cross-links on the surface of various cells, while λ-carrageenan may function as a contact activator. Depletion of peritoneal macrophages was performed by overnight pretreatment with diphtheria toxin in transgenic mice, resulting in a significant (p < 0...
February 23, 2018: Acta Microbiologica et Immunologica Hungarica
Manuel Gregoritza, Kathrin Abstiens, Moritz Graf, Achim M Goepferich
Reducing burst effects, providing controlled release, and safeguarding biologics against degradation are a few of several highly attractive applications for microgels in the field of controlled release. However, the incorporation of proteins into microgels without impairing stability is highly challenging. In this proof of concept study, the combination of microfluidics and thiol-ene photoclick chemistry was evaluated for the fabrication of antibody-loaded microgels with narrow size distribution. Norbornene-modified eight-armed poly(ethylene glycol) with an average molecular mass of 10,000 Da, 20,000 Da, or 40,000 Da were prepared as macromonomers for microgel formation...
February 19, 2018: European Journal of Pharmaceutics and Biopharmaceutics
Romina Martínez-Rubio, José Luis Acebes, Antonio Encina, Anna Kärkönen
Maize (Zea mays L.) suspension-cultured cells habituated to a cellulose biosynthesis inhibitor 2,6-dichlorobenzonitrile (DCB) have a modified cell wall, in which the reduction in the cellulose content is compensated by a network of highly cross-linked feruloylated arabinoxylans and the deposition of lignin-like polymers. For both arabinoxylan cross-linking and lignin polymerization, class III peroxidases (POXs) have been demonstrated to have a prominent role. For the first time, a comparative study of POX activity and isoforms in control and cellulose-impaired cells has been addressed, also taking into account their cellular distribution in different compartments...
February 21, 2018: Physiologia Plantarum
Yujin Lee, Eun-Ah You, Young-Geun Ha
For constructing bio-inspired functional films with various superhydrophobic functions including self-cleaning, anti-corrosion, anti-bioadhesion, and oil-water separation, hydrophobic nanomaterials have been widely used as crucial structural components. In general, hydrophobic nanomaterials, however, cannot form strong chemical bond networks in organic-inorganic hybrid composite films because of the absence of chemically compatible binding components. Herein, we report the rationally designed, multifunctional self-assembled nanoparticles with tunable functionalities of covalent cross-linking and hydrophobicity for constructing three-dimensionally interconnected superhydrophobic composite films via a facile solution-based fabrication at room temperature...
February 19, 2018: ACS Applied Materials & Interfaces
Jinqiang Wang, Yanqi Ye, Jicheng Yu, Anna R Kahkoska, Xudong Zhang, Chao Wang, Wujin Sun, Ria D Corder, Zhaowei Chen, Saad A Khan, John B Buse, Zhen Gu
A bioinspired glucose-responsive insulin delivery system for self-regulation of blood glucose levels is desirable for improving health and quality of life outcomes for patients with type 1 and advanced type 2 diabetes. Here we describe a painless core-shell microneedle array patch consisting of degradable cross-linked gel for smart insulin delivery with rapid responsiveness and excellent biocompatibility. This gel-based device can partially dissociate and subsequently release insulin when triggered by hydrogen peroxide (H2 O2 ) generated during the oxidation of glucose by a glucose-specific enzyme covalently attached inside the gel...
February 19, 2018: ACS Nano
Sonu Kumar, Piotr Cieplak
Posttranslational modifications that involve either reversible covalent modification of proteins or irreversible proteolysis are central to the regulation of key cellular mechanisms, including apoptosis, cell-cycle regulation and signal transduction. There is mounting evidence suggesting cross-talk between proteases and kinases. For instance: caspases, a class of proteases involved in programmed cell death-apoptosis, cleave a large set of various types of proteins. Simultaneously, kinases restrict caspase activity by phosphorylating their protein substrates in the vicinity of cleavage site...
February 16, 2018: Apoptosis: An International Journal on Programmed Cell Death
Thomas S Neugebauer, Michael Franz, Stephanie Frankenberger, Rik R Tykwinski, Thomas Drewello
Laser-induced cross-linking of polyynes is successfully hindered when the polyyne is encapsulated as part of a rotaxane and therefore protected by a surrounding macrocycle. When the rotaxane is electrosprayed, however, noncovalent aggregate ions are efficiently formed. Aggregates of considerable size (including more than 50 rotaxane molecules with masses beyond 100k Da) and charge states (up to 13 charges and beyond) have been observed. Either protons or sodium cations act as the charge carriers. These aggregates are not formed when the individual components of the rotaxane, i...
February 14, 2018: Journal of Chemical Physics
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