Materials for the controlled release of nitric oxide (NO) are of interest for therapeutic applications. However, to date, many suffer from toxicity and stability issues, as well as poor performance. Herein, we propose a new NO adsorption/release mechanism through the formation of nitrites on the skeleton of a titanium-based metal–organic framework (MOF) that we named MIP-177, featuring a suitable set of properties for such an application: (i) high NO storage capacity (3 μmol mg−1solid), (ii) excellent biocompatibility at therapeutic relevant concentrations (no cytotoxicity at 90 μg mL−1 for wound healing) due to its high stability in biological media (<9 % degradation in 72 hours) and (iii) slow NO release in biological media (≈2 hours for 90 % release). The prospective application of MIP-177 is demonstrated through NO-driven control of mitochondrial respiration in cells and stimulation of cell migration, paving the way for the design of new NO delivery systems for wound healing therapy. 相似文献
The synthesis of NiCo2O4 spinel by several nanocasting strategies (i.e., multi-step nanocasting, one-step nanocasting and soft-templating), in which
nickel and cobalt nitrates are used as precursors and Pluronic P123 as surfactant, is explored. First, in the multi-step nanocasting,
the effect of the impregnation method (evaporation, solid–liquid and two-solvent) of the SBA-15 silica template on the morphology
of NiCo2O4 replica is investigated. The evaporation method seems to be the best choice to obtain mesoporous NiCo2O4 powder which, after calcination at 375 °C and subsequent template removal, displays the highest surface area (93.1 m2/g). We have also checked the feasibility of the one-step nanoscating approach for the synthesis of ordered NiCo2O4 arrays, though this methodology entails severe difficulties, mainly related to the different decomposition temperature of
the nitrate precursors and the P123 surfactant. Finally, randomly oriented, aggregated NiCo2O4 nanoparticles are obtained by means of P123 surfactant-assisted soft-templating approach. 相似文献
Two different and novel composite monolithic materials with multimodal hierarchical porosity were prepared. The composites were prepared by immobilizing porous clay hetrostructure (PCH) and aluminum pillared clay (PILC), individually, into highly porous framework of a foam like monolith zeolite (MZ). The MZ was prepared hydrothermally, by following a polyurethane foam (PUF) based induced-template procedure and, consists of ZSM-5 framework. The MZ was fabricated into different composite materials through a simple dip coating method. Characterization of these materials with X-ray, SEM, and low temperature nitrogen adsorption techniques shows that composites materials are the morphological mixture (hybrid) of constituting materials. It also show that PCH based composites are meso and microporous, where as PILC based composites are essentially microporous in nature. The materials were further characterized for their hierarchical porosities by adsorption of two VOCs, which were toluene and n-hexane, under ambient conditions. The difference in adsorption of various sized (small to large) molecules was considered to work out the hierarchy of pores in these materials. With help of adsorption data, the hierarchical porosity was established into three size ranges, based on pore volumes of certain pore size ranges (>0.36 nm–<0.49 nm, >0.49 nm–<0.66 nm, and ≥0.66 nm). Water adsorption studies on these materials confirm that the coating of zeolite monolith with clay based adsorbents can also modify the hydrophobicity of original zeolite structure. 相似文献
The mechanism of glyme catalyzed ester aminolysis in chlorobenzene should be modified by including a new reaction pathway that shows a first-order dependence on the concentration of the phase transfer catalyst and a second-order dependence on butylamine. 相似文献
A flow injection method is proposed for the determination of phenylephrine hydrochloride in pharmaceutical dosage forms. The method involves the use of on-line solid-phase extraction by means of a microcolumn containing Dowex 50W X8 ion-exchange resin for the separation of the analyte prior to colour development and spectrophotometric detection in the visible region.
The influence of preconcentration flow, preconcentration pH and elution volume was studied.
The method exhibits appropriate linearity (r2 = 0.9999) which was proved statistically by means of the “F”-test. When applied to commercial samples containing several active ingredients and excipients, a significant reduction of interferences was found. Accuracy, evaluated by means of the spike recovery method was in the range 99.7–100.8%, with precision (R.S.D., %) better than 1%.
In order to achieve the automation the system was controlled from a notebook computer by means of a program written in QuickBASIC language. Under these conditions, a sampling frequency of 40 samples per hour could be attained. 相似文献
We report a joint computational and luminescence study on the low-lying excited states of sym-triazines, namely, 1,3,5-triazine (1) and the ubiquitous herbicides atrazine [6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (2)] and ametryn [6-methylthio-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (3)]. Geometrical structures, energetics, and transition and state properties of I and 2 were computed at the TD-DFT, CASSCF, and CASPT2 levels of theory. The fluorescence and phosphorescence emission spectra, lifetimes, and fluorescence quantum yields were measured for the three compounds, and from these, the energies of the lowest excited states and their corresponding radiative rates were determined. The predictions from CASPT2 calculations are in good agreement with the experimental results obtained from the luminescence studies and allow the interpretation of different absorption and emission features. 相似文献
Straight-run bitumens are no longer suitable in new asphalt mixtures. Consequently, the use of modified bitumens has become more important. In order to both improve binders’ mechanical properties and prevent it from phase separation whilst stored at high temperature, the paving industry is currently developing new modification routes based on reactive agents. This work studies the use of thiourea, which has proven to efficiently broaden the temperature interval over which the binder demonstrates an adequate performance. On the one hand, viscous flow and dynamic shear tests indicate an enhancement in the high in-service temperature strength, along with a reduced thermal susceptibility. On the other hand, results of dynamic flexural tests reveal a significant decrease in the binder glass transition temperature. Finally, the use of master curves and a further frequency/temperature conversion are proposed, in order to attain a suitable viscoelastic characterisation of bituminous binders at low temperatures. 相似文献
The microenvironment formed by lauroyl and stearoyl derivatives of chitosan in solution has been studied using two fluorescent
probes, pyrene and nabumetone. Existence or not of microdomains formed by polymolecular associations, the inherent hydrophobicity
of them in aqueous solution, and the influence of degree of substitution (DS) of derivatives were investigated by emission
properties of pyrene and strengthened by the photophysical behavior of nabumetone. Additionally, the ratio between the fluorescence
intensities of first (~372 nm) to the third (~384 nm) bands of the emission spectrum of pyrene was used to determine the critical
aggregation concentration (CAC). In a previous work, it was already reported the characterization of chitosan derivatives
by three spectroscopic techniques (13C-NMR, 1H-NMR and infrared), as well as data on the solubility and swelling-index of them. In addition of that, the new results show
that the investigated lauroyl and stearoyl derivatives of chitosan are expected to be potential models for applications in
the medical field. 相似文献