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Self-Healing Polymers
Published in Asit Baran Samui, Smart Polymers, 2022
The pyrrolidinone-based monomer and substituted acrylamide react in the presence of ε-poly-L-lysine (EPL) to form enzyme-assisted, dual-network, self-healing hydrogels (EDHs) with autonomous self-healing and antimicrobial ability.56 This is followed by the introduction of plasma amine oxidase (PAO) so that the oxidation of primary amines of EPL occurs in the air to form imine bonds (−CH = N−) and thus a secondary cross-linking network is formed. This enzyme-induced EDH system, having the dynamic covalent bonds of the Schiff base as well as the hydrogen-bonding interactions, exhibits autonomous healing without the need for any external stimuli. Broken gels combine together without any visible joint via self-healing over 6 h at 25°C and the mechanical properties at the weld line are the same as the original sample. The higher amount of EPL enhances the enzyme-induced Schiff base reaction rate, which, in turn, forms more dynamic imine bonds (−CH = N−). The imine bonds accelerate the self-healing rate. The presence of an ionic attraction between EPL and the target tissue allows it to exhibit adhesive properties. The materials have the property of fast wound dressing also.
Metabolism and Toxicity of Occupational Neurotoxicants: Genetic, Physiological, and Environmental Determinants
Published in Lucio G. Costa, Luigi Manzo, Occupatinal Neurotoxicology, 2020
Stefano M. Candura, Luigi Manzo, Anna F. Castoldi, Lucio G. Costa
The microsomal FAD-containing monooxygenase (FMO, mixed-function amine oxidase) competes with the P450 system in the oxidation of amines. Multiple forms of the enzyme are present in several species and tissues, however it is unlikely that there are as many isoforms of FMO as there are of cytochromes P450. The FMO system converts tertiary amines to amine oxides, secondary amines to hydroxyl amines and nitrones, and primary amines to hydroxylamines and oximes. It also oxidizes sulfur compounds (sulfides, thioethers, thiols, thiocarbamates) and organ-ophosphates.14 In particular, FMO activates certain organophosphorus pesticides containing at least one C-P bond (e.g., fonofos), or a thioether linkage (e.g., phorate). Such compounds are substrates for both cytochromes P450 and FMO.10
Assemblies of Organic and Inorganic Molecular Systems on Solid Substrates
Published in Sanjay V. Malhotra, B. L. V. Prasad, Jordi Fraxedas, Molecular Materials, 2017
Direct electron transfer to redox enzymes has been extensively studied where electron transfer between redox enzymes such as cytochrome c has been achieved. Various examples include horseradish peroxidase, azurin, hemoglobin, myoglobin, and laccase. SAMs act as a platform to incorporate enzymes by adsorption or covalent attachment and the electron transfer kinetics is found to be altered.128,129 Enzyme active center in most of the cases is embedded deep within the glycoprotein and direct electron transfer is quite difficult. Willner and coworkers have shortened the distance with an electrically wired enzyme electrode using a mediator, pyrroloquinoline quinone (PQQ). The mediator is covalently attached to a cysteamine-modified gold surface using a coupling agent, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide). The PQQ-terminated SAM is then used to attach flavin adenine dinucleotide (FAD), a cofactor for GOx. The PQQ/FAD conjugate is then used to reconstitute apo-glucose oxidase to provide a GOx enzyme electrode mediated by PQQ.130 Hess and coworkers reported another approach to achieve direct electron transfer to enzymes with a redox active center embedded deep within the glycoprotein where direct electron transfer to amine oxidase in its native configuration is achieved by the formation of SAMs on gold substrates.131
Oxygenation of copper(I) complexes containing fluorine tagged tripodal tetradentate chelates: significant ligand electronic effects
Published in Journal of Coordination Chemistry, 2022
Runzi Li, Firoz Shah Tuglak Khan, Marcos Tapia, Shabnam Hematian
The dioxygen (O2) chemistry of synthetic copper(I) complexes and the oxidative properties of the resulting copper-O2 adducts are of importance due to their potential relevance to copper-containing proteins vital for aerobic life as well as their applications in chemical catalysis [1–5]. In nature, copper-dioxygen interactions are essential for facilitating an array of biological functions in many proteins including the dioxygen-carrier hemocyanin, monooxygenases where O2 is activated such as in tyrosinase, dopamine β-hydroxylase, and phenylalanine hydroxylase, or oxidases where O2 is reduced to H2O or H2O2 including in laccase, galactose oxidase, ascorbate oxidase, amine oxidase, and the heme-copper binuclear active site of cytochrome c oxidase [2,6–8].