RESUMO
Lipase from Thermomyces lanuginosus (TLL) was immobilized onto a novel heterofunctional support, divinyl sulfone (DVS) superparamagnetic nanoparticles (SPMNs) functionalized with polyethyleneimine (PEI). Particle size and zeta potential measurements, elemental analysis, X-ray powder diffraction, magnetic measurements, and infrared spectroscopy analysis were used to characterize the TLL preparations. At pH 10, it was possible to achieve 100 % of immobilization yield in 1â¯h. The immobilization pH gives TLL preparations with different stabilities; indeed the TLL preparation immobilized at pH 5.0 was the most stable during the thermal inactivation at all pH values. For the hydrolysis of racemic methyl mandelate, the nanobiocatalysts immobilized at pH 5.0 and blocked with ethylenediamine (EDA) and ethanolamine (ETA) obtained good enantioselectivities (68 % and 72 %, respectively) with high catalytic activities in the reaction medium at pH 7.0. The operational stability of the systems was evaluated in the esterification reaction of benzyl alcohol, obtaining up to 61 % conversion after the seventh reaction cycle. These results show that SPMN@PEI-DVS support is a robust strategy for the easy and rapid recovery of the nanobiocatalyst by applying a magnetic field, showing great potential for industrial applications.
Assuntos
Enzimas Imobilizadas/química , Eurotiales/enzimologia , Lipase/química , Nanopartículas Magnéticas de Óxido de Ferro/química , Polietilenoimina/química , Sulfonas/química , Compostos de Benzil/metabolismo , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Esterificação , Etanolamina/química , Etilenodiaminas/química , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Lipase/metabolismo , Temperatura , Fatores de TempoRESUMO
To enhance the enzymatic digestibility of cashew apple bagasse (CAB) feedstock in order to produce sugar fermentation-derived bioproducts, the CAB was subjected to three different pretreatments with the ionic liquid 2-hydroxyl-ethylammonium acetate (2-HEAA) and characterized by FTIR, NMR and chemical methods. All conditions were able to delignify CAB, however the best lignin removal (95.8%) was achieved through the method performed with 8.7% w/w of CAB/2-HEAA ratio at 130°C for 24h. Although the cellulose crystallinity has been increased in CAB treated with the ionic liquid, but this fact did not influence its digestibility. Nevertheless, the pretreatment with 2-HEAA enhanced significantly the cellulose digestibility, increasing the glucose yield from 48 to 747.72mgglucose/gCAB. Furthermore, 2-HEAA pretreatment was efficient even with reused ionic liquid, obtaining high glucose concentration.
Assuntos
Anacardium/química , Biotecnologia/métodos , Líquidos Iônicos/química , Acetatos/química , Anacardium/metabolismo , Celulase/química , Celulase/metabolismo , Celulose/química , Celulose/metabolismo , Etanolamina/química , Glucose/química , Glucose/metabolismo , Hidrólise , Resíduos Industriais , Lignina/química , Espectroscopia de Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
This work analyzes the surface properties of PE-containing membranes modified at the head group region by the addition of methyl and ethyl residues at or near the amine group. These residues alter the lipid-lipid and lipid-water interactions by changes in the hydrogen bonding capability and the charge density of the amine group thus affecting the electrostatic interaction. The results obtained by measuring the dipole potential, the zeta potential, the area per lipid and the compressibility properties allow to conclude that the H-bonding capability prevails in the lipid-lipid interaction. The non polar groups attached to the C2-carbon of the ethanolamine chain introduces a steric hindrance against compression and increases the dipole potential. The analysis of areas suggests that lipids with methylated head groups have a much larger compressibility at expense of the elimination of hydration water, which is congruent with the broader extent of the hysteresis loop.
Assuntos
Fosfatidiletanolaminas/química , Dimiristoilfosfatidilcolina/química , Etanolamina/química , Ligação de Hidrogênio , Água/químicaRESUMO
Here, we describe the chemical characterization of the inclusion complex between diclofenac (DCF) and methyl-beta-cyclodextrin (M-beta-CD) in the presence or absence of monoethanolamine (MEA). Several techniques were used to analyze the complex both in solution and in the solid state. Solubility of DCF was increased by the addition of M-beta-CD. However, the DCF solubility increase was more significant by the addition of M-beta-CD in the presence of MEA. In vitro permeation experiments through excised human skin revealed that DCF was enhanced by M-beta-CD. Nevertheless, further improvement in the flux and the permeability coefficient of DCF was obtained by the ternary system DCF-M-beta-CD-MEA.
Assuntos
Diclofenaco/química , Diclofenaco/metabolismo , Etanolamina/química , Absorção Cutânea , Pele/metabolismo , beta-Ciclodextrinas/química , Varredura Diferencial de Calorimetria , Humanos , Espectroscopia de Ressonância Magnética , Permeabilidade , Solubilidade , TermogravimetriaRESUMO
In a previous work [M. Mandaji, et al., this issue] a sample stacking method was theoretically modeled and experimentally demonstrated for analytes with low dpK(a)/dT (analytes carrying carboxylic groups) and BGEs with high dpH/dT (high pH-temperature-coefficients). In that work, buffer pH was modulated with temperature, inducing electrophoretic mobility changes in the analytes. In the present work, the opposite conditions are studied and tested, i.e. analytes with high dpK(a)/dT and BGEs that exhibit low dpH/dT. It is well known that organic bases such as amines, imidazoles, and benzimidazoles exhibit high dpK(a)/dT. Temperature variations induce instantaneous changes on the basicity of these and other basic groups. Therefore, the electrophoretic velocity of some analytes changes abruptly when temperature variations are applied along the capillary. This is true only if BGE pH remains constant or if it changes in the opposite direction of pK(a) of the analyte. The presence of hot and cold sections along the capillary also affects local viscosity, conductivity, and electric field strength. The effect of these variables on electrophoretic velocity and band stacking efficacy was also taken into account in the theoretical model presented. Finally, this stacking method is demonstrated for lysine partially derivatized with naphthalene-2,3-dicarboxaldehyde. In this case, the amino group of the lateral chain was left underivatized and only the alpha amino group was derivatized. Therefore, the basicity of the lateral amino group, and consequently the electrophoretic mobility, was modulated with temperature while the pH of the buffer used remained unchanged.