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This work describes the preparation of a molecularly imprinted polymer (MIP) platform on polyethylene terephthalate (MIP-PET) via RAFT polymerization for analyzing tartrazine using a smartphone. The MIP-PET platform was characterized using Fourier transform infrared (FTIR) techniques, Raman Spectroscopy, X-ray photoelectron spectroscopy (XPS), and confocal microscopy. The optimal pH and adsorption time conditions were determined. The adsorption capacity of the MIP-PET plates with RAFT treatment (0.057 mg cm-2) was higher than that of the untreated plates (0.028 mg cm-2). The kinetic study revealed a pseudo-first-order model with intraparticle diffusion, while the isotherm study indicated a fit for the Freundlich model. Additionally, the MIP-PET demonstrated durability by maintaining its adsorption capacity over five cycles of reuse without significant loss. To quantify tartrazine, images were captured using a smartphone, and the RGB values were obtained using the ImageJ® free program. A partial least squares regression (PLS) was performed, obtaining a linear range of 0 to 7 mg L-1 of tartrazine. The accuracy of the method was 99.4% (4.97 ± 0.74 mg L-1) for 10 samples of 5 mg L-1. The concentration of tartrazine was determined in two local soft drinks (14.1 mg L-1 and 16.5 mg L-1), with results comparable to the UV-visible spectrophotometric method.
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Patients with bone diseases often experience increased bone fragility. When bone injuries exceed the body's natural healing capacity, they become significant obstacles. The global rise in the aging population and the escalating obesity pandemic are anticipated to lead to a notable increase in acute bone injuries in the coming years. Our research developed a novel DLP resin for 3D printing, utilizing poly(ethylene glycol diacrylate) (PEGDA) and various monomers through the PET-RAFT polymerization method. To enhance the performance of bone scaffolds, triply periodic minimal surfaces (TPMS) were incorporated into the printed structure, promoting porosity and pore interconnectivity without reducing the mechanical resistance of the printed piece. The gyroid TPMS structure was the one that showed the highest mechanical resistance (0.94 ± 0.117 and 1.66 ± 0.240 MPa) for both variants of resin composition. Additionally, bioactive particles were introduced to enhance the material's biocompatibility, showcasing the potential for incorporating active compounds for specific applications. The inclusion of bioceramic particles produces an increase of 13% in bioactivity signal for osteogenic differentiation (alkaline phosphatase essay) compared to that of control resins. Our findings highlight the substantial improvement in printing precision and resolution achieved by including the photoabsorber, Rose Bengal, in the synthesized resin. This enhancement allows for creating intricately detailed and accurately defined 3D-printed parts. Furthermore, the TPMS gyroid structure significantly enhances the material's mechanical resistance, while including bioactive compounds significantly boosts the polymeric resin's biocompatibility and bioactivity (osteogenic differentiation).
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The development of composite materials with thermo-optical properties based on smart polymeric systems and nanostructures have been extensively studied. Due to the fact of its ability to self-assemble into a structure that generates a significant change in the refractive index, one of most attractive thermo-responsive polymers is poly(N-isopropylacrylamide) (PNIPAM), as well as its derivatives such as multiblock copolymers. In this work, symmetric triblock copolymers of polyacrylamide (PAM) and PNIPAM (PAMx-b-PNIPAMy-b-PAMx) with different block lengths were prepared by reversible addition-fragmentation chain-transfer polymerization (RAFT). The ABA sequence of these triblock copolymers was obtained in only two steps using a symmetrical trithiocarbonate as a transfer agent. The copolymers were combined with gold nanoparticles (AuNPs) to prepare nanocomposite materials with tunable optical properties. The results show that copolymers behave differently in solution due to the fact of variations in their composition. Therefore, they have a different impact on the nanoparticle formation process. Likewise, as expected, an increase in the length of the PNIPAM block promotes a better thermo-optical response.
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In this research, a brush-like polyaniline (poly(2-acrylamide-2-methyl-1-propanesulfonate)-g-polyaniline)-b-poly(N-vinylcarbazole) (BL PAni) was developed as a strategy to overcome the limited processability and dedoping above pH 4 of conventional polyaniline (PAni). For the BL PAni synthesis, RAFT polymerization (homopolymer), RAFT-mediated surfactant-free emulsion polymerization (block copolymer), and interfacial oxidative polymerization were applied to graft the PAni chains. NMR and FT-IR spectroscopies were performed to confirm the structural elucidation of the reaction pathways, while the thermal properties were analyzed by TGA and DSC. Notably, the BL PAni presents absorption throughout the visible region and up to the near-infrared, showing dedoping resistance at up to 80 °C and at a neutral pH. The absorption range of the BL PAni, block copolymer, and homopolymer were studied by UV-Vis spectroscopy in solid-state and dispersion/solution, highlighting BL PAni and poly(anilinium 2-acrylamide-2-methyl-1-propanesulfonate)-b-poly(N-vinylcarbazole) (PAAMP-b-PVK) due to the π-stacking between the anilinium and carbazole groups. The cyclic voltammetry confirmed the persistence of electroactivity at a pH near 7.
Assuntos
Acrilamidas , Polímeros , Compostos de Anilina , Concentração de Íons de Hidrogênio , Espectroscopia de Infravermelho com Transformada de Fourier , TemperaturaRESUMO
A mathematical model for the kinetics, composition and molar mass development of the bulk reversible addition-fragmentation chain transfer (RAFT) copolymerization of glycidyl methacrylate (GMA) and styrene (St), at several GMA molar feed fractions at 103 °C, in the presence of 2-cyano isopropyl dodecyl trithiocarbonate as the RAFT agent and 1,1'-azobis(cyclohexane carbonitrile), as the initiator, is presented. The copolymerization proceeded in a controlled manner and dispersities of the copolymers remained narrow even at high conversions. Experimental data and calculated profiles of conversion versus time, composition versus conversion and molar mass development for the RAFT copolymerization of St and GMA agreed well for all conditions tested, including high-conversion regions. The kinetic rate constants associated with the RAFT- related reactions and diffusion-controlled parameters were properly estimated using a weighted nonlinear multivariable regression procedure. The mathematical model developed in this study may be used as an aid in the design and upscaling of industrial RAFT polymerization processes.
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In this study, six-arm star-shaped poly(N-vinylcaprolactam) (PNVCL) polymers prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization were subjected to aminolysis reaction using hexylamine. Chemically crosslinked gels or highly end-functionalized star polymers can be obtained depending mainly on the type of solvent used during the transformation of the RAFT functional group. An increase in the viscosity of the solution was observed when the aminolysis was carried out in THF. In contrast, when the reaction was conducted in dichloromethane, chain-end thiol (PNVCL)6 star polymers could be obtained. Moreover, when purified (PNVCL-SH)6 star polymers are in contact with THF, the gelation occurs in just a few minutes, with an obvious increase in viscosity, to form physical gels that become chemically crosslinked gels after 12 h. Interestingly, when purified (PNVCL-SH)6 star polymers were stirred in distilled water, even at high aqueous solution concentration (40 mg/mL), there was no increase in the viscosity or gelation, and no evident gels were observed. The analysis of the hydrodynamic diameter (Dh) by dynamic light scattering (DLS) did not detect quantifiable change even after 4 days of stirring in water. On the other hand, the thiol groups in the (PNVCL-SH)6 star polymers were easily transformed into trithiocarbonate groups by addition of CS2 followed by benzyl bromide as demonstrated by UV-Vis spectroscopical analysis and GPC. After the modification, the (PNVCL)6 star polymers exhibit an intense yellow color typical of the absorption band of trithiocarbonate group at 308 nm. To further demonstrate the highly effective new trithiocarbonate end-functionality, the PNVCL polymers were successfully chain extended with N-isopropylacrylamide (NIPAM) to form six-arm star-shaped PNIPAM-b-PNVCL block copolymers. Moreover, the terminal thiol end-functionality in the (PNVCL-SH)6 star polymers was linked via disulfide bond formation to l-cysteine to further demonstrate its reactivity. Zeta potential analysis shows the pH-responsive behavior of these star polymers due to l-cysteine end-functionalization. By this using methodology and properly selecting the solvent, various environment-sensitive star polymers with different end-groups could be easily accessible.
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Herein, we report a novel type of symmetrical trithiocarbonate chain transfer agent (CTA) based diphenylmethyl as R groups. The utilization of this CTA in the Reversible Addition-Fragmentation chain Transfer (RAFT) process reveals an efficient control in the polymerization of methacrylic monomers and the preparation of block copolymers. The latter are obtained by the (co)polymerization of styrene or butyl acrylate using a functionalized macro-CTA polymethyl methacrylate (PMMA) previously synthesized. Data show low molecular weight dispersity values (D < 1.5) particularly in the polymerization of methacrylic monomers. Considering a typical RAFT mechanism, the leaving groups (R) from the fragmentation of CTA should be able to re-initiate the polymerization (formation of growth chains) allowing an efficient control of the process. Nevertheless, in the case of the polymerization of MMA in the presence of this symmetrical CTA, the polymerization process displays an atypical behavior that requires high [initiator]/[CTA] molar ratios for accessing predictable molecular weights without affecting the D. Some evidence suggests that this does not completely behave as a common RAFT agent as it is not completely consumed during the polymerization reaction, and it needs atypical high molar ratios [initiator]/[CTA] to be closer to the predicted molecular weight without affecting the D. This work demonstrates that MMA and other methacrylic monomers can be polymerized in a controlled way, and with "living" characteristics, using certain symmetrical trithiocarbonates.
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Extracellular adenosine plays important roles in modulating the immune responses. We have previously demonstrated that infection of dendritic cells (DC) by Leishmania amazonensis leads to increased expression of CD39 and CD73 and to the selective activation of the low affinity A2B receptors (A2B R), which contributes to DC inhibition, without involvement of the high affinity A2A R. To understand this apparent paradox, we now characterized the alterations of both adenosine receptors in infected cells. With this aim, bone marrow-derived DC from C57BL/6J mice were infected with metacyclic promastigotes of L. amazonensis. Fluorescence microscopy revealed that L. amazonensis infection stimulates the recruitment of A2B R, but not of A2A R, to the surface of infected DC, without altering the amount of mRNA or the total A2B R density, an effect dependent on lipophosphoglycan (LPG). Log-phase promastigotes or axenic amastigotes of L. amazonensis do not stimulate A2B R recruitment. A2B R clusters are localized in caveolin-rich lipid rafts and the disruption of these membrane domains impairs A2B R recruitment and activation. More importantly, our results show that A2B R co-localize with CD39 and CD73 forming a "purinergic cluster" that allows for the production of extracellular adenosine in close proximity with these receptors. We conclude that A2B R activation by locally produced adenosine constitutes an elegant and powerful evasion mechanism used by L. amazonensis to down-modulate the DC activation.
Assuntos
5'-Nucleotidase/metabolismo , Antígenos CD/metabolismo , Apirase/metabolismo , Caveolina 1/metabolismo , Células Dendríticas/imunologia , Leishmaniose/imunologia , Microdomínios da Membrana/imunologia , Receptor A2B de Adenosina/metabolismo , Animais , Células Dendríticas/metabolismo , Células Dendríticas/parasitologia , Células Dendríticas/patologia , Imunidade , Imunomodulação , Leishmania/imunologia , Leishmaniose/metabolismo , Leishmaniose/parasitologia , Leishmaniose/patologia , Macrófagos/imunologia , Macrófagos/metabolismo , Macrófagos/parasitologia , Macrófagos/patologia , Masculino , Microdomínios da Membrana/parasitologia , Microdomínios da Membrana/patologia , Camundongos , Camundongos Endogâmicos C57BLRESUMO
A Disintegrin And Metalloprotease 23 (ADAM23) is a member of the ADAMs family of transmembrane proteins, mostly expressed in nervous system, and involved in traffic and stabilization of Kv1-potassium channels, synaptic transmission, neurite outgrowth, neuronal morphology and cell adhesion. Also, ADAM23 has been linked to human pathological conditions, such as epilepsy, cancer metastasis and cardiomyopathy. ADAM23 functionality depends on the molecule presence at the cell surface and along the secretory pathway, as expected for a cell surface receptor. Because endocytosis is an important functional regulatory mechanism of plasma membrane receptors and no information is available about the traffic or turnover of non-catalytic ADAMs, we investigated ADAM23 internalization, recycling and half-life properties. Here, we show that ADAM23 undergoes constitutive internalization from the plasma membrane, a process that depends on lipid raft integrity, and is redistributed to intracellular vesicles, especially early and recycling endosomes. Furthermore, we observed that ADAM23 is recycled from intracellular compartments back to the plasma membrane and thus has longer half-life and higher cell surface stability compared with other ADAMs. Our findings suggest that regulation of ADAM23 endocytosis/stability could be exploited therapeutically in diseases in which ADAM23 is directly involved, such as epilepsy, cancer progression and cardiac hypertrophy.
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Proteínas ADAM/metabolismo , Endocitose , Membrana Celular/metabolismo , Células Cultivadas , Endossomos/metabolismo , Meia-Vida , Humanos , Microdomínios da Membrana/metabolismoRESUMO
Entre el 15 y el 17 del pasado mes de mayo de 2021 se llevó a cabo un nuevo congreso virtual del American College of Cardiology, uno de los eventos científicos más esperados de la cardiología mundial. Se contó con expositores de excelente nivel y la presentación de trabajos destacados que han realizado un aporte significativo a nuestra práctica clínica referidos a un gran abanico de situaciones frecuentes: cirugía cardíaca, cardiología intervencionista, manejo de arritmias. A continuación, seleccionamos y resumimos algunos de los trabajos más significativos: Aspirin versus clopidogrel for chronic maintenance monotherapy after percutaneous coronary intervention (HOST-EXAM). TicAgrelor versus CLOpidogrel in Stabilized Patients with Acute Myocardial Infarction (TALOS-AMI). Left Atrial Appendage Occlusion during Cardiac Surgery to Prevent Stroke III (LAAOS III). Sotagliflozin in Patients with Diabetes and Recent Worsening Heart Failure (SOLOIST-WHF). A Randomized Ablation-based atrial Fibrillation rhythm control versus rate control Trial in patients with heart failure and high burden Atrial Fibrillation (RAFT-AF). Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-Term Effectiveness (ADAPTABLE).
Summary: The Annual meeting of the American Cardiology College Congress was held virtually between 15th and 17th of May in present 2021. This is indeed one of the most expected and relevant scientific events in the world of Cardiology. We had excellent speakers and outstanding presentations updating central themes in our clinical practice referring to a wide range of frequent situations such us: cardiac surgery, interventional cardiology, management of arrhythmias. Bellow, we select and summarize some of the most significant works: Aspirin versus clopidogrel for chronic maintenance monotherapy after percutaneous coronary intervention (HOST-EXAM). TicAgrelor versus CLOpidogrel in Stabilized Patients with Acute Myocardial Infarction (TALOS-AMI). Left Atrial Appendage Occlusion during Cardiac Surgery to Prevent Stroke III (LAAOS III). Sotagliflozin in Patients with Diabetes and Recent Worsening Heart Failure (SOLOIST-WHF). A Randomized Ablation-based atrial Fibrillation rhythm control versus rate control Trial in patients with heart failure and high burden Atrial Fibrillation (RAFT-AF). Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-Term Effectiveness (ADAPTABLE).
De 15 a 17 de maio de 2021, foi realizada uma nova reunião virtual do congresso anual do American College of Cardiology, um dos eventos científicos mais relevantes do mundo da cardiologia. Houve excelentes palestrantes e a apresentação de estudos notáveis ââque atualizaram temas centrais em nossa prática clínica referentes a uma ampla gama de situações comuns: cirurgia cardíaca, cardiologia intervencionista, manejo de arritmias. A seguir, selecionamos e resumimos algumas das obras mais significativas: Aspirina versus clopidogrel para monoterapia de manutenção crônica após intervenção coronária percutânea (EXAME-HOST). TicAgrelor versus CLOpidogrel em pacientes estabilizados com infarto agudo do miocárdio (TALOS-AMI). Oclusão do apêndice atrial esquerdo durante a cirurgia cardíaca para prevenir acidente vascular cerebral III (LAAOS III). Sotagliflozina em pacientes com diabetes e insuficiência cardíaca recente (SOLOIST-WHF). Um ensaio randomizado de controle de ritmo de fibrilação atrial baseado em ablação versus controle de frequência em pacientes com insuficiência cardíaca e fibrilação atrial de alta carga (RAFT-AF). Dosagem de aspirina: um estudo centrado no paciente que avalia os benefícios e eficácia a longo prazo (ADAPTÁVEL).
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Different synthetic strategies were tested for the incorporation of galactose molecules on thermoresponsive nanogels owing to their affinity for receptors expressed in cancer cells. Three families of galactose-functionalized poly(N-vinylcaprolactam) nanogels were prepared with the aim to control the introduction of galactose-moieties into the core, the core-shell interface and the shell. First and second of the above mentioned, were prepared via surfactant free emulsion polymerization (SFEP) by a free-radical mechanism and the third one, via SFEP/reversible addition-fragmentation chain transfer (RAFT) polymerization. Synthetic recipes for the SFEP/free radical method included besides N-vinylcaprolactam (NVCL), a shell forming poly(ethylene glycol) methyl ether methacrylate (PEGMA), while the galactose (GAL) moiety was introduced via 6-O-acryloyl-1,2,:3,4-bis-O-(1-methyl-ethylidene)-α-D-galactopiranose (6-ABG, protected GAL-monomer): nanogels I, or 2-lactobionamidoethyl methacrylate (LAMA, GAL-monomer): nanogels II. For the SFEP/RAFT methodology poly(2-lactobionamidoethyl methacrylate) as GAL macro-chain transfer agent (PLAMA macro-CTA) was first prepared and on a following stage, the macro-CTA was copolymerized with PEGMA and NVCL, nanogels III. The crosslinker ethylene glycol dimethacrylate (EGDMA) was added in both methodologies for the polymer network construction. Nanogel's sizes obtained resulted between 90 and 370 nm. With higher content of PLAMA macro-CTA or GAL monomer in nanogels, a higher the phase-transition temperature (TVPT) was observed with values ranging from 28 to 46 °C. The ρ-parameter, calculated by the ratio of gyration and hydrodynamic radii from static (SLS) and dynamic (DLS) light scattering measurements, and transmission electron microscopy (TEM) micrographs suggest that core-shell nanogels of flexible chains were obtained; in either spherical (nanogels II and III) or hyperbranched (nanogels I) form.
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Well-defined amphiphilic, biocompatible and partially biodegradable, thermo-responsive poly(N-vinylcaprolactam)-b-poly(ε-caprolactone) (PNVCL-b-PCL) block copolymers were synthesized by combining reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerizations (ROP). Poly(N-vinylcaprolactam) containing xanthate and hydroxyl end groups (X-PNVCL-OH) was first synthesized by RAFT/macromolecular design by the interchange of xanthates (RAFT/MADIX) polymerization of NVCL mediated by a chain transfer agent containing a hydroxyl function. The xanthate-end group was then removed from PNVCL by a radical-induced process. Finally, the hydroxyl end-capped PNVCL homopolymer was used as a macroinitiator in the ROP of ε-caprolactone (ε-CL) to obtain PNVCL-b-PCL block copolymers. These (co)polymers were characterized by Size Exclusion Chromatography (SEC), Fourier-Transform Infrared spectroscopy (FTIR), Proton Nuclear Magnetic Resonance spectroscopy (1H NMR), UV-vis and Differential Scanning Calorimetry (DSC) measurements. The critical micelle concentration (CMC) of the block copolymers in aqueous solution measured by the fluorescence probe technique decreased with increasing the length of the hydrophobic block. However, dynamic light scattering (DLS) demonstrated that the size of the micelles increased with increasing the proportion of hydrophobic segments. The morphology observed by cryo-TEM demonstrated that the micelles have a pointed-oval-shape. UV-vis and DLS analyses showed that these block copolymers have a temperature-responsive behavior with a lower critical solution temperature (LCST) that could be tuned by varying the block copolymer composition.
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Relation between the renal function and the membrane environment where the organic anion transporters Oat1 and Oat3 are localized is scarce. The aim of this study was to examine the Oat1 and Oat3 distribution in different cellular fractions under physiological conditions as well as the effects of extrahepatic cholestasis on membrane distribution of both proteins. Besides, the potential role of jaundice serum on the Oat1 and Oat3 expression in suspensions of renal tubular cells was evaluated. Cellular and membrane fractions of renal cortex were obtained from control rats to evaluate Oat1 and Oat3 protein expressions. Other rats were subjected to bile duct ligation (BDL) or Sham operation to determine the membrane distribution of Oat1 and Oat3 between lipid raft domains (LRD) and non-LRD. Incubation of renal cortical cells with serum from Sham and BDL were also performed to study Oat1 and Oat3 protein expressions. In physiological conditions, Oat1 and Oat3 were concentrated in LRD. The pathology induced a shift of Oat1 from LRD to non-LRD, while Oat3 showed no changes in its distribution. In cells exposed to BDL serum, Oat1 protein expression in membranes significantly increased. For Oat3, no difference between groups was observed. The Oat1 redistribution to non-LRD in BDL could be favoring the increase in renal transport of organic anions previously observed. This change was specific to Oat1. The in vitro experiment allows to conclude that some component present in BDL serum is responsible for the alterations observed in Oat1 expression in cortical membranes.
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Icterícia Obstrutiva/metabolismo , Córtex Renal/metabolismo , Microdomínios da Membrana/metabolismo , Proteína 1 Transportadora de Ânions Orgânicos/metabolismo , Transportadores de Ânions Orgânicos Sódio-Independentes/metabolismo , Animais , Ductos Biliares/metabolismo , Masculino , Ratos , Ratos WistarRESUMO
Polymeric biomaterials capable of delivering nitric oxide (NO) topically can be used to enhance skin blood flow (SkBF) and accelerate wound healing. Herein, we used reversible addition-fragmentation chain transfer radical (RAFT) polymerization to synthesize the first poly(vinyl alcohol) (PVA) functionalized with terminal NO-releasing S-nitrosothiol (RSNO) groups for topical NO delivery. This strategy was based on the synthesis of a precursor amino-terminated PVA (PVA-NH2), which was next functionalized with iminothiolane yielding 4-imino-4-amino-PVA-butane-1-thiol (PVA-SH), and finally S-nitrosated yielding S-nitroso 4-imino-4-amino-PVA-butane-1-thiol (PVA-SNO). Real-time chemiluminescence NO detection showed that blended films of pure PVA with PVA-SNO with mass ratios 30:70, 50:50 and 70:30 release NO with initial rates ranging from 1 to 12 nmol g-1 min-1, and lead to a 2 to 10-fold dose-response increase in the SkBF, after topical application on the ventral forearm of volunteers. These results show that PVA-SNO is a potential platform for topical NO delivery in biomedical applications.
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Óxido Nítrico/metabolismo , Álcool de Polivinil/metabolismo , S-Nitrosoglutationa/metabolismo , Pele/metabolismo , Velocidade do Fluxo Sanguíneo , Humanos , Pele/irrigação sanguíneaRESUMO
In this work three CTAs trithiocarbonate-type were synthesized-bifunctional (with PEG), trifunctional (with glycerol), and tetrafunctional (PERT)-and used in the controlled polymerization of 2-(acryloyloxy)ethyl cholate (CAE) via reversible addition-fragmentation chain transfer (RAFT) polymerization. The resulting macroCTAs containing a cholic acid-derived polymer were chain extended with N-isopropylacrylamide with or without acrylic acid. The thermosensitive and/or pH properties of these copolymers were studied in PBS solutions. The copolymers synthesized without poly(acrylic acid) (PAAc) were unstable above the transition temperature. Similar behavior was observed for the copolymer solutions containing PAAc (2% in feed) at lower values of pH showing a faster precipitation above the LCST. On the contrary, copolymer solutions containing PAAc showed great stability at higher pH values for a longer time period at 37 °C. Interestingly, the Dh of the aggregates ranged from 18 to 30 nm in all copolymers (with or without PAAc) below the transition temperature, although the topology and the block sequence in the chain were significantly different.
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Copolymerization of isoprene (IP) with glycidyl methacrylate (GMA) was performed under RAFT (reversible addition-fragmentation chain-transfer) polymerization conditions in a platform for high-output experimentation. Covering the range between 1 and 0.2 molar fraction of IP in the feed, four sets of reactions were carried out at 10, 15, 20, and 30 h at 115 °C. The kinetic data obtained were used to estimate the reactivity ratios using a nonlinear least-squares approach (NLLS). Reactivity ratios rGMA = 0.61 and rIP = 0.74 indicate that both monomers tend to crosspropagate in agreement with known literature values. Concerning the RAFT study, relatively good control and livingness of the copolymerization was observed except for the experiment in which IP represents 20 mol % in the feed. 1H NMR characterization confirmed the presence of both monomers in the final copolymer, particularly the presence of the epoxy ring of GMA which is susceptible to post polymerization reactions. Finally, preliminary results on the hydrogenation of various polymers are discussed.
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Butadienos/química , Compostos de Epóxi/química , Hemiterpenos/química , Metacrilatos/química , Polímeros/síntese química , Técnicas de Química Combinatória , Estrutura Molecular , Polimerização , Polímeros/químicaRESUMO
Polymerization through reversible addition-fragmentation chain-transfer (RAFT) polymerization has been extensively employed for the production of polymers with controlled molar mass, complex architectures and copolymer composition distributions intended for biomedical and pharmaceutical applications. In the present work, RAFT miniemulsion copolymerizations of methyl methacrylate with acrylic acid and methacrylic acid were conducted to prepare hydrophilic polymer nanoparticles and compare cell uptake results after bioconjugation with bovine serum albumin (BSA), used as a model biomolecule. Obtained results indicate that the RAFT agent 2-cyano-propyl-dithiobenzoate allowed for successful free radical controlled methyl methacrylate copolymerizations and performed better when methacrylic acid was used as comonomer. Results also indicate that poly(methyl methacrylate-co-methacrylic acid) nanoparticles prepared by RAFT copolymerization and bioconjugated with BSA were exceptionally well accepted by cells, when compared to the other produced polymer nanoparticles because cellular uptake levels were much higher for particles prepared in presence of methacrylic acid, which can probably be associated to its high hydrophilicity.
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Resumen La espinaca es una planta de alto valor nutricional, mostrando gran acogida en su presentación "baby". La producción en hidroponía está limitada por la solución nutritiva, siendo la acuaponía un potencial complemento a este factor limitante. El objetivo de esta investigación fue definir los cambios de niveles de nutrientes en la solución hidropónica en espinaca baby. Se trabajó con 24 plántulas de espinaca en hidroponía de cama flotante usando solución "La Molina" en tanques de 50 L; se realizaron 5 repeticiones y 3 réplicas. Para cada réplica se cosechó cada tres semanas, registrando semanalmente variables fisicoquímicas de la solución. Además, se llevó a cabo un muestreo al inicio y final de cada réplica, evaluando las siguientes variables: número y longitud de hojas, área foliar, peso fresco y seco de la parte aérea. Se obtuvo en orden descendiente la siguiente extracción de macronutriente: N>K+>Ca2+>P y micronutrientes: Mn2+>Fe2+. Durante el ciclo de cultivo el pH de la solución osciló entre 6.00-6.97, el oxígeno disuelto entre 4.93-7.54 mg/L y la conductividad disminuyó constantemente a lo largo del ciclo, inició en 1558-1592 µS/cm y finalizó entre 1140-1275 µS/cm. Se obtuvo un TCC= 0.00002-0.00003 g/cm2/día; TRC=0.16, 0.15 y 0.14 g/g/día y TAN=0.006, 0.005 y 0.006 g/cm2/día para las réplicas 1, 2 y 3, respectivamente. Este estudio revela que esta planta podría tener buenos rendimientos en un sistema acuapónico, especialmente por los requerimientos de N, Ca2+>P, no obstante, se deberían adicionar bajas cantidades de algunos micronutrientes, que suelen ser escasos en los sistemas acuapónicos.
Abstract Baby spinach has a high nutritional value, and good entry in specialized markets. Its hydroponic production is limited by nutrient solution, and the aquaponic systems can avoid this limitation. The goal in this work was to evaluate nutrient level changes in hydroponic solution during baby spinach crop. 24 spinach plants were planted in 50 L tanks in floating hydroponic beds, using a modified "La Molina" nutrient solution. They were carried out 5 replications and 3 harvest. Water physicochemical values were registered every week, and plants were harvested after three weeks. Plant samples were also taken before planting (initial time) and after three weeks. Number of leaves, leaf length, leaf area, fresh and dry weight of the aerial part of each plant were recorded. The macronutrient extraction was obtained in descending order: N> P>K+> Ca2+ and micronutrients: Mn2+>Fe2+. pH values were maintained between 6.00-6.97, and DO levels were 4.93-7.54 mg/L. Initial conductivity was about 1558-1592 µS/cm and finally diminished to 1140-1275 µS/cm. CGR= 0.00002-0.00003 g/cm2/day; RGR=0.16, 0.15 y 0.14 g/g/day and NAR=0.006, 0.005 y 0.006 g/cm2/day for replica 1, 2 and 3 respectively. This study reveals that this plant could have good field performance in aquaponic system, especially due to the requirements of N, Ca2+>P, however low amounts of some micronutrients should be added, which are usually scarce in aquaponic systems
Resumo O espinafre é uma planta de alto valor nutricional, apresentando grande aceitação em sua apresentação "baby". A produção de hidroponia é limitada pela solução nutritiva, com a aquaponia sendo um complemento potencial para esse fator limitante. O objetivo desta pesquisa foi definir as alterações dos níveis de nutrientes na solução hidropônica em espinafre bebê. Trabalhamos com 24 mudas de espinafre em hidroponia de leito flutuante usando solução "La Molina" em tanques de 50 L; 5 repetições e 3 repetições foram realizadas. Para cada replicação, foi colhida a cada três semanas, registrando-se variáveis físico-químicas semanais da solução. Além disso, foi realizada uma amostragem no início e no final de cada réplica, avaliando-se as seguintes variáveis: número e comprimento de folhas, área foliar, massa fresca e seca da parte aérea. A seguinte extração de macronutrientes foi obtida em ordem decrescente: N> K +> Ca2 +> P e micronutrientes: Mn2 +> Fe2 +. Durante o ciclo de cultivo, o pH da solução variou entre 6,00-6,97, o oxigênio dissolvido entre 4,93-7,54 mg/L e a condutividade diminuiu constantemente ao longo do ciclo, começando em 1558-1592 µS/cm e terminando entre 1140-1275 µS/cm. Obteve-se um TCC = 0,00002-0,00003 g / cm2 / dia; CRT = 0,16, 0,15 e 0,14 g / g / dia e TAN = 0,006, 0,005 e 0,006 g / cm2 / dia para os replicados 1, 2 e 3, respectivamente. Este estudo revela que esta planta pode ter bons rendimentos em um sistema aquapônico, especialmente por causa das exigências de N, Ca2+>P, porém pequenas quantidades de alguns micronutrientes devem ser adicionadas, que geralmente são escassas em sistemas aquapônicos.
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This article presents the preparation of matrices from two new families of fumaric copolymers and the effect of structural differences on their physicochemical and biological behavior. Diisopropyl fumarate (DIPF) and poly(ethylene glycol) methyl ether methacrylate (OEGMA) or N-isopropylacrylamide (NIPAM) were copolymerized by conventional radical and RAFT polymerization to obtain lineal or start architectures, respectively. These copolymers were characterized by spectroscopic (FTIR and 1 H-NMR) and chromatographic methods. The thermal stability was studied by thermal gravimetric analysis, showing some differences in relation to the architecture and chemical nature of copolymers. SEM morphological analysis demonstrated that the surface of the matrices derived from OEGMA exhibited an irregular and rough surface, while DIPF-NIPAM copolymers presented smooth surface with nearly no significant porosity. The matrix obtained of both kinds of copolymers presented no cytotoxicity as it was evaluated using a model of macrophages on culture. Moreover, cell growth was better on the surfaces of the DIPF-NIPAM matrices, suggesting a good interaction with this matrix and its potential application as matrices for tissue engineering. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 195-203, 2019.