Enzyme immobilization strategies for the design of robust and efficient biocatalysts

Different strategies for the preparation of efficient and robust immobilized biocatalysts are here reviewed. Different physico-chemical approaches are discussed.i.- The stabilization of enzyme by any kind of immobilization on pre-existing porous supports.ii.- The stabilization of enzymes by multipoint covalent attachment on support surfaces.iii.- Additional stabilization of immobilized-stabilized enzyme by physical or chemical modification with polymers.These three strategies can be easily developed when enzymes are immobilized in pre-existing porous supports. In addition to that, these immobilized-stabilized derivatives are optimal to develop enzyme reaction engineering and reactor engineering. Stabilizations ranging between 1000 and 100,000 folds regarding diluted soluble enzymes are here reported.     

Inverse central ordering for the Newton interpolation formula

Numerical Algorithms - An inverse central ordering of the nodes is proposed for the Newton interpolation formula. This ordering may improve the stability for certain distributions of nodes. For...     

Suppressed Mobility of Negative Charges in Polymer Electrolytes with an Ether‐Functionalized Anion

Suppressing the mobility of anionic species in polymer electrolytes (PEs) is essential for mitigating the concentration gradient and internal cell polarization, and thereby improving the stability and cycle life of rechargeable alkali metal batteries. Now, an ether‐functionalized anion (EFA) is used as a counter‐charge in a lithium salt. As the salt component in PEs, it achieves low anionic diffusivity but sufficient Li‐ion conductivity. The ethylene oxide unit in EFA endows nanosized self‐agglomeration of anions and trapping interactions between the anions and its structurally homologous matrix, poly(ethylene oxide), thus suppressing the mobility of negative charges. In contrast to previous strategies of using anion traps or tethering anions to a polymer/inorganic backbone, this work offers a facile and elegant methodology on accessing selective and efficient Li‐ion transport in PEs and related electrolyte materials (for example, composites and hybrid electrolytes).     

Dilatometric model for determining the formation of austenite during continuous heating in medium carbon steel

Journal of Thermal Analysis and Calorimetry - A model was developed to predict the formation of austenite and dilatometric behavior during continuous heating in AISI 1045 steel, which has an...     

Janus Gold Nanostars–Mesoporous Silica Nanoparticles for NIR-Light-Triggered Drug Delivery

Janus gold nanostar–mesoporous silica nanoparticle ( AuNSt–MSNP ) nanodevices able to release an entrapped payload upon irradiation with near infrared (NIR) light were prepared and characterized. The AuNSt surface was functionalized with a thiolated photolabile molecule ( 5 ), whereas the mesoporous silica face was loaded with a model drug (doxorubicin) and capped with proton-responsive benzimidazole-β-cyclodextrin supramolecular gatekeepers ( N 1 ). Upon irradiation with NIR-light, the photolabile compound 5 photodissociated, resulting in the formation of succinic acid, which induced the opening of the gatekeeper and cargo delivery. In the overall mechanism, the gold surface acts as a photochemical transducer capable of transforming the NIR-light input into a chemical messenger (succinic acid) that opens the supramolecular nanovalve. The prepared hybrid nanoparticles were non-cytotoxic to HeLa cells, until they were irradiated with a NIR laser, which led to intracellular doxorubicin release and hyperthermia. This induced a remarkable reduction in HeLa cells viability.     

Excited-State Dynamics of Thienoguanosine,an Isomorphic Highly Fluorescent Analogue of Guanosine

Thienoguanosine (^thG) is an isomorphic analogue of guanosine with promising potentialities as fluorescent DNA label. As a free probe in protic solvents, ^thG exists in two tautomeric forms, identified as the H1, being the only one observed in nonprotic solvents, and H3 keto–amino tautomers. We herein investigate the photophysics of ^thG in solvents of different polarity, from water to dioxane, by combining time-resolved fluorescence with PCM/TD-DFT and CASSCF calculations. Fluorescence lifetimes of 14.5–20.5 and 7–13 ns were observed for the H1 and H3 tautomers, respectively, in the tested solvents. In methanol and ethanol, an additional fluorescent decay lifetime (≈3 ns) at the blue emission side (λ≈430 nm) as well as a 0.5 ns component with negative amplitude at the red edge of the spectrum, typical of an excited-state reaction, were observed. Our computational analysis explains the solvent effects observed on the tautomeric equilibrium. The main radiative and nonradiative deactivation routes have been mapped by PCM/TD-DFT calculations in solution and CASSCF in the gas phase. The most easily accessible conical intersection, involving an out-of plane motion of the sulfur atom in the five-membered ring of ^thG, is separated by a sizeable energy barrier (≥0.4 eV) from the minimum of the spectroscopic state, which explains the large experimental fluorescence quantum yield.     

GC‐FID determination and pharmacokinetic studies of oleanolic acid in human serum

Analytical interest of OA determination in human serum has increased owing to the increasing interest in pharmaceutical research by pharmaceutical properties. A simple, specific, precise and accurate GC method with flame ionization detector (FID) developed and validated for the determination of oleanolic acid (OA) in human serum (HS). To an aliquot of HS, internal standard was added and a combination of liquid–liquid extraction with a mixture of diethyl ether‐isopropyl alcohol, filtration and consecutive GC resulted in separation and quantification of OA. The organic phase was analyzed using a GC system equipped with a 30 × 0.25 mm i.d. Rtx‐65TG capillary column and FID detection. Total chromatographic time was 10 min and no interfering peaks from endogenous components in blank serum were observed. The OA/internal standard peak area ratio was linearly fitted to the OA concentration (r = 0.992) over the range 10–1500 ng/mL. The mean serum extraction recovery of OA was 96.7 ± 1.0% and the lower limit of quantification based on 5 mL of serum was 10.7 ng/mL. The intra‐day coefficient of variation ranged from 1.3 to 3.6% and inter‐day varied from 1.4 to 4.5%. The developed method was used to study the pharmacokinetics of OA after oral administration in humans. The assay was simple, sensitive, precise and accurate for the use in the study of the mechanisms of absorption and distribution of OA in humans. Copyright © 2015 John Wiley & Sons, Ltd.