Silver decorated mesoporous carbons are interesting systems that may offer effective solutions for advanced wound care products by combining the well-known anti-microbial activity of silver ...nanoparticles with the versatile properties of ordered mesoporous carbons. Silver is being used as a topical antimicrobial agent, especially in wound repair. However, while silver shows bactericidal properties, it is also cytotoxic at high concentrations. Therefore, the incorporation of silver into ordered mesoporous carbons allows to exploit both silver's biological effects and mesoporous carbons' biocompatibility and versatility with the purpose of conceiving silver-doped materials in light of the growing health concern in wound care.
The wound healing potential of an ordered mesoporous carbon also doped with two different loadings of silver nanoparticles (2 wt% and 10 wt%), was investigated through a biological assessment study based on different assays (cell viability, inflammation, antibacterial tests, macrophage-conditioned fibroblast and human keratinocyte cell cultures).
The results show silver-doped ordered mesoporous carbons to positively condition cell viability, with a cell viability percentage >70% even for 10 wt% Ag, to modulate the expression of inflammatory cytokines and of genes involved in tissue repair (KRT6a, VEGFA, IVN) and remodeling (MMP9, TIMP3) in different cell systems. Furthermore, along with the biocompatibility and the bioactivity, the silver-doped ordered mesoporous carbons still retain an antibacterial effect, as shown by a maximum of 13.1% of inhibited area in the Halo test. The obtained results clearly showed that the silver-doped ordered mesoporous carbons exhibit both good biocompatibility and antibacterial effect with enhanced re-epithelialization, angiogenesis promotion and tissue regeneration.
These findings suggest that the exceptional properties of silver-doped ordered mesoporous carbons could be exploited in the treatment of acute and chronic wounds and that such carbon materials could be potential candidates for use in medical devices for wound healing purposes, in particular, the 10 wt% loading, as the results showed to be the most effective.
The effect of the partial substitution of La with Ce on the crystal structure and the final hydrogen storage properties of the alloys. Display omitted
► Absorption-based systems exploit the ...properties of reversible metal hydrides. ► AB5 intermetallics are mostly popular for thermal desorption compressors. ► Investigation of H2 absorption/desorption properties of LaNi5 and its derivatives. ► LaNi5 thermodynamic properties adjustment by partially replacing La with rare earths.
The present work has been aiming at the synthesis and study of a series of La1−xCexNi5 (x=0, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8) alloys in an attempt to investigate possible alterations of the hydrogen absorption/desorption properties The alloys were prepared by induction melting of the constituent elements. The systematic characterization of all new compounds by means of XRD and hydrogen sorption measurements revealed the effect of the partial substitution of La with Ce on the crystal structure and the final hydrogen storage properties of the alloys. Extensive absorption/desorption experiments (Van’t Hoff diagrams) have shown that such alloys can be used to build a metal hydride compressor (MHC), compressing H2 gas from 0.2MPa to 4.2MPa using cold (20°C) and hot (80°C) water.
Biological waste such as residues from the food and beverage industry provides a valuable and abundant resource to be used as a precursor for the synthesis of activated carbons that can be ...subsequently employed as adsorbents for, e.g., hydrogen storage. Materials with a large specific surface area and pores of appropriate size are necessary to achieve reasonable hydrogen adsorption capacity. Here, we present the repeatable synthesis of activated carbons from coffee waste, i.e., spent coffee grounds and coffee silver skins, on the basis of two independently synthesized batches. The carbonization process under nitrogen gas flow followed by chemical activation with solid potassium hydroxide results in microporous carbons with bimodal pore size distribution and specific surface area up to 3300 and 2680 m2/g based on Brunauer–Emmett–Teller and density functional theory methods, respectively. The materials exhibit excellent hydrogen adsorption performance under cryogenic conditions (77 K), reaching high and fully reversible excess gravimetric hydrogen uptake values of up to 5.79 wt % at 37 bar, and total capacities exceeding 9 wt % at 100 bar.
Both LiBHsub.4 and NaBHsub.4 are well known for having high hydrogen contents, but also high decomposition temperatures and slow hydrogen absorption–desorption kinetics, preventing their use for ...hydrogen storage applications. The low melting temperature (219 °C) of their eutectic mixture 0.71 LiBHsub.4 –0.29 NaBHsub.4 allowed the synthesis of a new composite material through the melt infiltration of the hydrides into the ~5 nm diameter pores of a CMK-3 type carbon. A composite of 0.71 LiBHsub.4 –0.29 NaBHsub.4 and non-porous graphitic carbon discs was also prepared by similar methods for comparison. Both composites showed improved kinetics and a partial reversibility of the dehydrogenation/rehydrogenation reactions. However, the best results were observed for the CMK-3 nanoconfined hydrides; a consistent uptake of about 3.5 wt.% Hsub.2 was recorded after five hydrogenation/dehydrogenation cycles for an otherwise non-reversible system. The improved hydrogen release kinetics are attributed to carbon–hydride surface interactions rather than nanoconfinement, while enhanced heat transfer due to the carbon support may also play a role. Likewise, the carbon–hydride contact proved beneficial in terms of reversibility, without, however, ruling out the potential positive effect of pore confinement.
Introduction: Silver decorated mesoporous carbons are interesting systems that may offer effective solutions for advanced wound care products by combining the well-known antimicrobial activity of ...silver nanoparticles with the versatile properties of ordered mesoporous carbons. Silver is being used as a topical antimicrobial agent, especially in wound repair. However, while silver shows bactericidal properties, it is also cytotoxic at high concentrations. Therefore, the incorporation of silver into ordered mesoporous carbons allows to exploit both silver's biological effects and mesoporous carbons' biocompatibility and versatility with the purpose of conceiving silver-doped materials in light of the growing health concern in wound care. Methods: The wound healing potential of an ordered mesoporous carbon also doped with two different loadings of silver nanoparticles (2 wt% and 10 wt%), was investigated through a biological assessment study based on different assays (cell viability, inflammation, antibacterial tests, macrophage-conditioned fibroblast and human keratinocyte cell cultures). Results: The results show silver-doped ordered mesoporous carbons to positively condition cell viability, with a cell viability percentage >70% even for 10 wt% Ag, to modulate the expression of inflammatory cytokines and of genes involved in tissue repair (KRT6a, VEGFA, IVN) and remodeling (MMP9, TIMP3) in different cell systems. Furthermore, along with the biocompatibility and the bioactivity, the silver-doped ordered mesoporous carbons still retain an antibacterial effect, as shown by a maximum of 13.1% of inhibited area in the Halo test. The obtained results clearly showed that the silver-doped ordered mesoporous carbons exhibit both good biocompatibility and antibacterial effect with enhanced re-epithelialization, angiogenesis promotion and tissue regeneration. Discussion: These findings suggest that the exceptional properties of silver-doped ordered mesoporous carbons could be exploited in the treatment of acute and chronic wounds and that such carbon materials could be potential candidates for use in medical devices for wound healing purposes, in particular, the 10 wt% loading, as the results showed to be the most effective. Keywords: ordered mesoporous carbon, silver nanoparticles, metal doped carbons, wound healing, tissue regeneration
Mesoporous carbon aerogels can modulate the release profiles of ibuprofen whereas in vitro toxicity profiles appear to be compatible as carriers for the oral delivery of poorly soluble drugs.
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Towards the development of novel drug carriers for oral delivery of poorly soluble drugs mesoporous aerogel carbons (CAs), namely CA10 and CA20 with different pore sizes (10 and 20nm, respectively), were evaluated. The non-steroidal anti-inflammatory lipophilic compound ibuprofen was incorporated via passive loading. The drug loaded carbon aerogels were systemically investigated by means of High-Resolution Transmission Electron Microscopy (HR-TEM), Nitrogen physisorption studies, X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC), X-ray photon electron spectroscopy (XPS) and ζ-potential studies. In vitro release studies were performed in simulated intestinal fluids reflecting both fasted (FaSSIF) and fed (FeSSIF) state conditions. Cytotoxicity studies were conducted with human intestinal cells (Caco-2). Drug was in an amorphous state in the pores of the carbon carrier as shown from the physicochemical characterization studies. The results showed marked differences in the release profiles for ibuprofen from the two aerogels in the media tested whereas in vitro toxicity profiles appear to be compatible with potential therapeutic applications at low concentrations.
In the present work, we synthesized and systematically characterized two novel graphene-based nanomaterials, a chemically reduced graphene oxide (GO) sponge and a microwave-exfoliated GO. Textural ...properties were determined by N2 adsorption/desorption at 77 K, while additional characterization techniques were employed, such as Micro-Raman Spectroscopy, Field-Emission Scanning Electron Microscopy and High-Resolution Transmission Electron Microscopy, to elucidate further the structural and morphological features. Both nanomaterials were additionally evaluated for their H2 storage capacity and were critically compared to commercially available carbons (e.g. few-layer graphenes, carbon nanotubes) based on systematic H2 adsorption/desorption measurements at 77 K between 0 and 1 bar. Maximum H2 gravimetric capacities of ∼0.5 wt% and ∼0.7 wt% were recorded at 77 K and 1 bar for the reduced GO sponge and the microwave-exfoliated GO, respectively.
•High-surface area GOs were synthesized by freeze drying and microwave radiation.•Porosity, structure and morphology were studied by BET, Raman, SEM and TEM.•H2 storage capacity was evaluated against commercial nanocarbons.•Reversible H2 storage with gravimetric capacities 0.5–0.7 wt% at 77 K and 1 bar.•H2 storage behavior was correlated to specific textural/surface features.
The targeted synthesis of metal-organic frameworks (MOFs) with open metal sites, following reticular chemistry rules, provides a straightforward methodology toward the development of advanced porous ...materials especially for gas storage/separation applications. Using a palladated tetracarboxylate metalloligand as a 4-connected node, we succeeded in synthesizing the first heterobimetallic In(III)/Pd(II)-based MOF with square-octahedron (soc) topology. The new MOF, formulated as In
O(L)
(H
O)
Cl·n(solv) (1), features the oxo-centered trinuclear clusters, In
(μ
-O)(-COO)
, acting as trigonal-prismatic 6-connected nodes that linked together with the metalloligand trans-PdCl
(PDC)
(L
) (PDC: pyridine-3,5-dicarboxylate) to form a 3D network. After successful activation of 1 using supercritical CO
, high-resolution microporous analysis revealed the presence of small micropores (5.8 Å) with BET area of 795 m
g
and total pore volume of 0.35 cm
g
. The activated solid shows high gravimetric (92.3 cm
g
) and volumetric (120.9 cm
cm
) CO
uptake at 273 K and 1 bar as well as high CO
/CH
(15.4 for a 50:50 molar mixture) and CO
/N
(131.7 for a 10:90 molar mixture) selectivity, with moderate Q
for CO
(29.8 kJ mol
). Slight modifications of the synthesis conditions led to the formation of a different MOF with an anionic framework, having a chemical formula Me
NH
In(L)· n(solv) (2). This MOF is constructed from pseudotetrahedral, mononuclear In(-COO)
nodes bridged by four L
linkers, resulting in a 3D network with PtS topology.
Hydrogen storage by cryoadsorption on porous materials has the advantages of low material cost, safety, fast kinetics, and high cyclic stability. The further development of this technology requires ...reliable data on the H2 uptake of the adsorbents, however, even for activated carbons the values between different laboratories show sometimes large discrepancies. So far no reference material for hydrogen cryoadsorption is available. The metal‐organic framework ZIF‐8 is an ideal material possessing high thermal, chemical, and mechanical stability that reduces degradation during handling and activation. Here, we distributed ZIF‐8 pellets synthesized by extrusion to 9 laboratories equipped with 15 different experimental setups including gravimetric and volumetric analyzers. The gravimetric H2 uptake of the pellets was measured at 77 K and up to 100 bar showing a high reproducibility between the different laboratories, with a small relative standard deviation of 3–4 % between pressures of 10–100 bar. The effect of operating variables like the amount of sample or analysis temperature was evaluated, remarking the calibration of devices and other correction procedures as the most significant deviation sources. Overall, the reproducible hydrogen cryoadsorption measurements indicate the robustness of the ZIF‐8 pellets, which we want to propose as a reference material.
Assuring the reliability of hydrogen cryoadsorption measurements requires a robust reference material. Here we distributed a commercially produced metal‐organic framework ZIF‐8 in the form of pellets for an interlaboratory study on hydrogen adsorption isotherms at 77 K. The results show a low standard deviation and prove the material batch′s high homogeneity, therefore, making ZIF‐8 pellets a promising candidate for a reference material.
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