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Immobilized enzymes have a very large surface region which is not in contact with the support surface and, thus, have potential as a target for novel stabilization strategies. In this paper, coating the surfaces of such enzymes with a highly hydrophilic and compact cross-linked poly-aminated polymer as a strategy to increase the thermal stability of the immobilized enzymes is proposed. In particular, Rhizomucor miehei lipase (RML) was immobilized by interfacial adsorption onto octyl-agarose and further coated with poly-allylamine (PAA), a polymer that is very rich in primary amino groups. Cross-linking of the PAA layer to coat the immobilized enzyme was carried out, in situ, by reaction with freshly oxidized dextran (aldehyde–dextran). The PAA layer only exerted moderate stabilizing effects (around 4-fold), but further cross-linking with aldehyde–dextran highly increased the stabilizing effects; the new derivative was 440-fold more stable than uncoated derivative at 55 °C and pH 7 and exhibited 6-fold more catalytic activity compared to the soluble enzyme used for immobilization. We hypothesize that the hydrophilicity of PAA reduces the exposure of internal hydrophobic pockets to the enzyme surface at high temperatures. Besides, the compactness of the polymer may reduce distortion of the enzyme surface during inactivation., This work was supported by the Spanish Ministry of Science and Innovation (grant numbers BIO2012-36861 and CTQ2015-70348-C2-1-R). We gratefully recognize the Spanish Ministry of Economy and Innovation for the “Juan de la Cierva” contract for Dr. Rocha-Martin (grant number IJCI-2014-19260)

Metal-free catalysis was successfully applied to polymerize ω-pentadecalactone (PDL) by ring-opening polymerization (ROP) using several amino-ended initiators, namely hexylamine, allylamine and O,O′-bis(3-aminopropyl)diethylene glycol. This polymerization method was suitable to prepare telechelic polyesters carrying functional-end groups. The technique was then extended to the synthesis of block copolymers by ROP of PDL using bisamino-ended poly(ethylene glycol) (Mn = 2600) as macroinitiator. PPDLx-PEG56-PPDLx triblock copolymers with Mn ranging between ∼4000 and ∼90,000 g ·mol−1 were synthesized and extensively characterized by NMR, DSC, TGA and XRD. The amphiphilic copolymers thus produced were demonstrated to be able to self-assemble in nanoparticles with average diameters of ∼100–200 nm and morphologies highly depending on blocks lengths. The described synthetic route distinguishes in providing “clean” amphiphilic copolymers, which are attractive candidates for biomedical applications. Ministerio de Economía y Competitividad MAT-2016- 77345-CO3-01, MAT-2016-77345-CO3-02

Hybrid (organic shell–inorganic core) nanoparticles have important applications in nanomedicine. Although the inorganic components of hybrid nanoparticles can be characterized readily using conventional transmission electron microscopy (TEM) techniques, the structural and chemical arrangement of the organic molecular components remains largely unknown. Here, we apply TEM to the physico-chemical characterization of Au nanoparticles that are coated with plasma-polymerized-allylamine, an organic compound with the formula C3H5NH2. We discuss the use of energy-filtered TEM in the low-energy-loss range as a contrast enhancement mechanism for imaging the organic shells of such particles. We also study electron-beam-induced crystallization and amorphization of the shells and the formation of graphitic-like layers that contain both C and N. The resistance of the samples to irradiation by high-energy electrons, which is relevant for optical tuning and for understanding the degree to which such hybrid nanostructures are stable in the presence of biomedical radiation, is also discussed.

In this work, we investigate the surface reactivity of substrates coated with thin layers (estimated thickness ≤30nm) of plasma polymerized allylamine films (PPAA), an amine-functionalized polymer deposited by plasma-enhanced chemical vapor deposition (PECVD) with radiofrequency (RF) discharges. Our results show that very thin layers, or islands, can retain on their surface molecules that are able to react through their NH functions. We have tested and assessed by X-Ray Electron Spectroscopy (XPS) and Quartz Crystal Microbalance (QCM) the surface density of chemical functions vs. layer thicknesses by using chemical derivatization with two types of agents: imine formation by a reaction of primary amine from the coating with aldehyde (Pentafluorobenzaldehyde, PFBA) and amide-bond formation by reaction with an activated carboxylic group (Succinimidyl Succinate Terminated Polyethylene glycol, EGSS). Results show that the PPAA coatings-even for very thin layers of a few nanometers-promote the chemisorption of the tagging molecules. The aging under air and evolution of reactive amine surface concentration with time under air are also presented. © 2010 Elsevier B.V.

Core-shell nanoparticles (CSNPs) were developed to get over therapeutic amount of kynurenic acid (KYNA) across the blood-brain barrier (BBB). Bovine serum albumin (BSA) was used as core for encapsulation of KYNA and the BSA/KYNA composite was finally encapsulated by poly(allylamine) hydrochloride (PAH) polymer as shell. In the interest of the optimization of the synthesis the BSA and KYNA interaction was studied by two-dimensional surface plasmon resonance (SPR) technique as well. The average size of d~100 nm was proven by dynamic light scattering (DLS) and transmission electron microscopy (TEM), while the structure of the composites was characterized by fluorescence (FL) and circular dichroism (CD) spectroscopy. The in vitro release properties of KYNA were investigated by a vertical diffusion cell at 25.0 °C and 37.5 °C and the kinetic of the release were discussed. The penetration capacity of the NPs into the central nervous system (CNS) was tested by an in vitro BBB model. The results demonstrated that the encapsulated KYNA had significantly higher permeability compared to free KYNA molecules. In the neurobiological serial of in vivo experiments the effects of peripherally administered KYNA with CSNPs were studied in comparison with untreated KYNA. These results clearly proved that KYNA in the CSNPs, administrated peripherally is suitable to cross the BBB and to induce electrophysiological effects within the CNS. As the neuroprotective properties of KYNA nowadays are proven, the importance of the results is obvious.

In this work, polyelectrolyte complexes (PECs) were formed by adding polyacrylic acid (PAA) or 4-O-methylglucuronoxylan (Xyl) on poly(allylamine hydrochloride) (PAH) solutions, at different ionic strength and neutral pH. Turbidity curves, charge densities of the cationic complexes determined by polyelectrolyte titration method, and z-potential values showed clear differences between both complexes. Stirring favourably reverses the effects of sedimentation of Xyl/PAH complexes, as demonstrated by colloidal stability tests. Adsorption studies on silica surfaces, performed by Quartz Crystal Microbalance with Dissipation (QCM-D) showed that PAA/PAH adsorbed complexes layers were rigid, while the corresponding Xyl/PAH layers were viscoelastic. Despite the different conformations, both complexes were adsorbed as spherical particles, as observed by Atomic Force Microscopy (AFM). Adsorption isotherms performed on fibre suspensions showed that the ionic strength of the liquid medium determines the amount of PEC retained. Finally, it was found that the papermaking properties were significantly increased due to the addition of these PECs. Fil: Mocchiutti, Paulina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulosica; Argentina Fil: Galván, María Verónica. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulosica; Argentina Fil: Peresin, María S.. Technical Research Center Of Finland; Finlandia Fil: Schnell, Carla Natali. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulosica; Argentina Fil: Zanuttini, Miguel Angel Mario. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulosica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina

Alternating films constructed upon successive deposition of redox polymer Os(bpy)2ClPyCH2NHpoly(allylamine) and antibiotin IgG were developed for amperometric immunosensor design. Cyclic voltammetric measurements were used to verify charge transport between redox sites and the redox surface concentration was estimated upon voltammetric peak integration. Biotin–antibiotin complex formation was evaluated using horseradish peroxidase as an enzyme label. Redox mediation between the modified electrode surface and the redox site in the enzyme was verified after substrate addition. Multilayer modified gold electrodes with biologically active antibiotin IgG molecules were employed for the development of a competitive immunoassay with electrochemical label detection. Keywords: Immunoassays, Bio-electrodes, Multilayers, Immunosensors, Redox polymers

The Heck arylation of olefins by the substrate-directed Heck–Matsuda strategy using arenediazonium salts, especially the tetrafluoroborates, constitutes an effective way to synthesize functionalized olefins, thus making them more valuable intermediates in organic synthesis. The basic principle of the method relies on the complexation of a cationic δ-aryl-palladium species to a nearby functional group on the substrate in which structural and electronic arrangement governs the arylation process in a regio- and stereoselective manner. The present review highlights this strategy focusing on some selected syntheses accomplished in our laboratory. The synthetic strategy includes the directed arylation of allylic acetates, allylamine derivatives, and functionalized cyclopentene substrates. Illustrative syntheses include the kavalactones yangonine, methysticin, and dehydromethysticin, the antifungal drug naftifine, the phytohormones abamine and abamine SG, the drug cinacalcet, and the muscle relaxant alverine. Moreover, the method was also applied to the successful total synthesis of the sphingosine 1-phosphate agonist VPC01091, a promising drug for the treatment of multiple sclerosis. The examples presented herein demonstrate the substrate-directed strategy method as a general one applicable to metal-catalyzed processes other than the palladium-catalyzed Heck reaction.

Layer-by-layer self-assembled films of a small organic molecule have been deposited by physiadsorbing the molecules with a polycation. Light-emitting devices have been fabricated based on layer-by-layer self-assembled films. Alizarin violet mixed with poly(allylamine hydrochloride) and poly(acrylic acid) have been used as polycation and polyanion, respectively. The pH of the polyanion has been varied which in turn controlled the film morphology, and device characteristics based on such films have been compared. Charge injection mechanisms have been studied in the devices, and barrier heights for charge carriers have been calculated. The results showed that lower turn-on current and higher light output can be obtained from the devices based on self-assembled films as compared to devices based on spin-cast films.

Plasma copolymerisation of functioned monomers with hydrocarbons has been used to provide a controllable range of specific functional groups on carbon fibres. Acrylic acid/hexane or octadiene plasma polymer promoted adhesion to epoxy resin whereas allyl alcohol did not. Allylamine coplasma polymers exhibited intermediate levels of adhesion. The CSTF data analysis of fragmentation was shown to be effective for the quantification of the effect of differing concentrations of functional groups.

The arylation reaction of primary and secondary amines has been investigated using nickel or palladium complexes as catalysts, and bromo- or chloroarenes as arylating agents. Among the complexes tested, the more efficient catalyst is the bis (bipyridyl) nickel (II) bromide, bipy 2 NiBr 2 , which affords for example high yields in the arylation of allylamine with m -bromotrifluoromethylbenzene. The reduction of the haloarene, sometimes observed with the nickel complexes, becomes predominant with palladium catalysts whatever the complex used. For the arylation of primary or secondary alcohols, the same nickel complex, bipy 2 NiBr 2 (in presence of base, particularly KHCO 3 ), prove to be the more active catalyst, even in regard to various usual copper catalysts. The reaction affords good yields in alkylarylethers, under relatively mild conditions. An attempted mechanism, based on a catalytic cycle with a nickel(I) active species, is formulated on account of earlier mechanistic investigations described in the literature. Lastly, an unexpected aminolysis of nitriles catalyzed by the nickel (II) bromide, which affords an interesting new way to amides, is described.

Although the existence of a membrane-bound (probably plasmalemmal) semicarbazide-sensitive amine oxidase (SSAO) is well established in various mammalian tissues, and especially within vascular smooth muscle, its importance and the possible consequences of its metabolism of certain physiological and xenobiotic amines in vivo are under continuing investigation. In this respect, there are major species-related differences in substrate specificity determined in vitro, not only towards the synthetic amine benzylamine, but also towards some other aromatic amines (e.g. tyramine, tryptamine, 2-phenylethylamine, dopamine, histamine) which are possible endogenous substrates. Inhibition of SSAO can potentiate the pharmacological activity of some amines in isolated tissue (e.g. blood vessel) preparations from some species. Recent evidence has accumulated that SSAO may also be involved in metabolizing endogenous aliphatic amines such as methylamine and aminoacetone, focussing attention on the fact that the aldehyde products (formaldehyde and methylglyoxal, respectively) are potentially cytotoxic agents. Indeed, SSAO has been implicated in experimental models of cardiovascular toxicity involving conversion of the industrial aliphatic amine allylamine to acrolein. In summary, metabolism by SSAO may reduce the physiological/pharmacological effects of some amines, but the resulting metabolites (aldehydes, H2O2) may also have important actions.