A Sulfonated Covalent Organic Framework for Atmospheric Water Harvesting.

We report a sulfonated covalent organic framework (COF) capable of atmospheric water harvesting in arid conditions. The isothermal water uptake profile of the framework was studied, and the network displayed steep water sorption at low relative humidity (RH) in temperatures of up to 45 °C, reaching a water uptake of 0.12 g·g-1 at 10% RH and even 0.08 g·g-1 at just 5% RH, representing some of the most extreme conditions on the planet. We found that the inclusion of sulfonate moieties shifted uptake in the water isotherm profiles to lower RH compared to non-sulfonated equivalents, demonstrating well the benefits of including these hydrophilic sites for water uptake in hot arid locations. Repeated uptake and desorption were performed on the network without significant detriment to its adsorption performance, demonstrating the potential of the sulfonated COF for real-world implementation.

MANNosylation of Mesoporous Silica Nanoparticles Modifies TLR4 Localization and NF-κB Translocation in T24 Bladder Cancer Cells.

D-mannose is widely used as non-antibiotic treatment for bacterial urinary tract infections. This application is based on a well-studied mechanism of binding to the type 1 bacterial pili and, therefore, blocking bacteria adhesion to the uroepithelial cells. To implement D-mannose into carrier systems, the mechanism of action of the sugar in the bladder environment is also relevant and requires investigation. Herein, two different MANNosylation strategies using mesoporous silica nanoparticles (MSNs) are described. The impact of different chemical linkers on bacterial adhesion and bladder cell response is studied via confocal microscopy imaging of the MSN interactions with the respective organisms. Cytotoxicity is assessed and the expression of Toll-like receptor 4 (TLR4) and caveolin-1 (CAV-1), in the presence or absence of simulated infection with bacterial lipopolysaccharide (LPS), is evaluated using the human urinary bladder cancer cell line T24. Further, localisation of the transcription factor NF-κB due to the MANNosylated materials is examined over time. The results show that MANNosylation modifies bacterial adhesion to the nanomaterials and significantly affects TLR4, caveolin-1, and NF-κB in bladder cells. These elements are essential components of the inflammatory cascade/pathogens response during urinary tract infections. These findings demonstrate that MANNosylation is a versatile tool to design hybrid nanocarriers for targeted biomedical applications.

Low-Temperature controlled synthesis of nanocast mixed metal oxide spinels for enhanced OER activity.

The controlled cation substitution is an effective strategy for optimizing the density of states and enhancing the electrocatalytic activity of transition metal oxide catalysts for water splitting. However, achieving tailored mesoporosity while maintaining elemental homogeneity and phase purity remains a significant challenge, especially when aiming for complex multi-metal oxides. In this study, we utilized a one-step impregnation nanocasting method for synthesizing mesoporous Mn-, Fe-, and Ni-substituted cobalt spinel oxide (Mn0.1Fe0.1Ni0.3Co2.5O4, MFNCO) and demonstrate the benefits of low-temperature calcination within a semi-sealed container at 150-200 °C. The comprehensive discussion of calcination temperature effects on porosity, particle size, surface chemistry and catalytic performance for the alkaline oxygen evolution reaction (OER) highlights the importance of humidity, which was modulated by a pre-drying step. The catalyst calcined at 170 °C exhibited the lowest overpotential (335 mV at 10 mA cm-2), highest current density (433 mA cm-2 at 1.7 V vs. RHE, reversible hydrogen electrode) and further displayed excellent stability over 22 h (at 10 mA cm-2). Furthermore, we successfully adapted this method to utilize cheap, commercially available silica gel as a hard template, yielding comparable OER performance. Our results represent a significant progress in the cost-efficient large-scale preparation of complex multi-metal oxides for catalytic applications.

Aspects of Gas Storage: Confined Geometry Effects on the High-Pressure Adsorption Behavior of Supercritical Fluids.

During the last decades, major progress was made concerning the understanding of subcritical low-pressure adsorption of fluids like nitrogen and argon at their boiling temperatures in nanoporous materials. It was possible to understand how structural properties affect the shape of the adsorption isotherms. However, within the context of gas storage applications, supercritical high-pressure gas adsorption is important. A key feature here is that the experimentally determined surface excess adsorption isotherm may exhibit a characteristic maximum at a certain pressure. For a given temperature and adsorptive/adsorbent system, the surface excess maximum (and the corresponding adsorbed amount) is related to the storage capacity of the adsorbent. However, there is still a lack of understanding of how key textural properties such as surface area and pore size affect details of the shape of supercritical high-pressure adsorption isotherms. To address these open questions, we have performed a systematic experimental study assessing the effect of pore size/structure on the supercritical adsorption isotherms of pure fluids such as C2H4, CO2, and SF6 over a wider range of temperatures and pressures on a series of model materials exhibiting well-defined pore sizes, i.e., ordered micro- and mesoporous materials (e.g., NaY zeolite, KIT-6 silica, and MCM-48 silica). A fundamental result of our experiments is a unique fluid-independent correlation between the pressure of the surface excess maximum pmax (at a given temperature) and the pore size (by taking into account the kinetic diameter of the fluid and the underlying effective attractive fluid-wall interaction). Summarizing, our results suggest important structure-property relationships, allowing one to determine, for given thermodynamic conditions, important information related to the optimal operating conditions for supercritical adsorption applications. The insights may also serve as a basis for optimizing and tailoring the properties of nanoporous adsorbent materials for gas storage applications.

Identification of inulin-responsive bacteria in the gut microbiota via multi-modal activity-based sorting.

Prebiotics are defined as non-digestible dietary components that promote the growth of beneficial gut microorganisms. In many cases, however, this capability is not systematically evaluated. Here, we develop a methodology for determining prebiotic-responsive bacteria using the popular dietary supplement inulin. We first identify microbes with a capacity to bind inulin using mesoporous silica nanoparticles functionalized with inulin. 16S rRNA gene amplicon sequencing of sorted cells revealed that the ability to bind inulin was widespread in the microbiota. We further evaluate which taxa are metabolically stimulated by inulin and find that diverse taxa from the phyla Firmicutes and Actinobacteria respond to inulin, and several isolates of these taxa can degrade inulin. Incubation with another prebiotic, xylooligosaccharides (XOS), in contrast, shows a more robust bifidogenic effect. Interestingly, the Coriobacteriia Eggerthella lenta and Gordonibacter urolithinfaciens are indirectly stimulated by the inulin degradation process, expanding our knowledge of inulin-responsive bacteria.

Silica nanoparticles: A review of their safety and current strategies to overcome biological barriers.

Silica nanoparticles (SNP) have gained tremendous attention in the recent decades. They have been used in many different biomedical fields including diagnosis, biosensing and drug delivery. Medical uses of SNP for anti-cancer, anti-microbial and theranostic applications are especially prominent due to their exceptional performance to deliver many different small molecules and recently biologics (mRNA, siRNA, antigens, antibodies, proteins, and peptides) at targeted sites. The physical and chemical properties of SNP such as large specific surface area, tuneable particle size and porosity, excellent biodegradability and biocompatibility make them an ideal drug delivery and diagnostic platform. Based on the available data and the pre-clinical performance of SNP, recent interest has driven these innovative materials towards clinical application with many of the formulations already in Phase I and Phase II trials. Herein, the progress of SNP in biomedical field is reviewed, and their safety aspects are analysed. Importantly, we critically evaluate the key structural characteristics of SNP to overcome different biological barriers including the blood-brain barrier (BBB), skin, tumour barrier and mucosal barrier. Future directions, potential pathways, and target areas towards rapid clinical translation of SNP are also recommended.

Powdered Hierarchically Porous Silica Monoliths for the Selective Extraction of Scandium.

Scandium (Sc) is a high value Critical Material that is most commonly used in advanced alloys. Due to current and potential supply limitations, there has been an international effort to find new and improved ways to extract Sc from existing and novel resources. Solid-phase extraction (SPE) is one promising approach for Sc recovery, particularly for use with low-grade feedstocks. Here, unfunctionalized, powdered hierarchically porous silica monoliths from DPS Inc. (DPS) are used for Sc extraction in batch and semicontinuous flow systems at model conditions. The sorbent exhibits excellent mass transfer properties, much like the whole monoliths, which should permit Sc to be rapidly recovered from large volumes of feedstock. The Sc adsorption capacity of the material is ∼142.7 mg/g at pH 6, dropping to ∼12.0 mg/g at pH 3, and adsorption is furthermore highly selective for Sc compared with the other rare earth elements (REEs). Under semicontinuous flow conditions, recovery efficiency is limited by a kinetic process. The primary mechanism responsible for the system's slow approach to equilibrium is the Sc adsorption reaction kinetics rather than inter- or intraparticle diffusion. Overall, this unmodified hierarchically porous silica powder from DPS shows great promise for the selective extraction of Sc from various feedstocks.

Morphology-Dependent Interaction of Silica Nanoparticles with Intestinal Cells: Connecting Shape to Barrier Function.

The intestinal compartment ensures nutrient absorption and barrier function against pathogens. Despite decades of research on the complexity of the gut, the adaptive potential to physical cues, such as those derived from interaction with particles of different shapes, remains less understood. Taking advantage of the technological versatility of silica nanoparticles, spherical, rod-shaped, and virus-like materials were synthesized. Morphology-dependent interactions were studied on differentiated Caco-2/HT29-MTX-E12 cells. Contributions of shape, aspect ratio, surface roughness, and size were evaluated considering the influence of the mucus layer and intracellular uptake pathways. Small particle size and surface roughness favored the highest penetration through the mucus but limited interaction with the cell monolayer and efficient internalization. Particles of a larger aspect ratio (rod-shaped) seemed to privilege paracellular permeation and increased cell-cell distances, albeit without hampering barrier integrity. Inhibition of clathrin-mediated endocytosis and chemical modulation of cell junctions effectively tuned these responses, confirming morphology-specific interactions elicited by bioinspired silica nanomaterials.

Influence of Pore Size and Surface Functionalization of Mesoporous Silica Nanoparticles on the Solubility and Antioxidant Activity of Confined Coenzyme Q10.

Coenzyme Q10 is a potent antioxidant that plays an important role in the maintenance of various biochemical pathways of the body and has a wide range of therapeutic applications. However, it has low aqueous solubility and oral bioavailability. Mesoporous silica nanoparticles (MCM-41 and SBA-15 types) exhibiting varying pore sizes and modified with phosphonate and amino groups were used to study the influence of pore structure and surface chemistry on the solubility, in vitro release profile, and intracellular ROS inhibition activity of coenzyme Q10. The particles were thoroughly characterized to confirm the morphology, size, pore profile, functionalization, and drug loading. Surface modification with phosphonate functional groups was found to have the strongest impact on the solubility enhancement of coenzyme Q10 when compared to that of pristine and amino-modified particles. Phosphonate-modified MCM-41 nanoparticles (i.e., MCM-41-PO3) induced significantly higher coenzyme Q10 solubility than the other particles studied. Furthermore, MCM-41-PO3 led to a twofold decrease in ROS generation in human chondrocyte cells (C28/I2), compared to the free drug in a DMSO/DMEM mixture. The results confirmed the significant contribution of small pore size and negative surface charge of MSNs that enable coenzyme Q10 confinement to allow enhanced drug solubility and antioxidant activity.

Immobilization of Agaricus bisporus Polyphenol Oxidase 4 on mesoporous silica: Towards mimicking key enzymatic processes in peat soils.

HYPOTHESIS: The use of immobilized enzyme-type biocatalysts to mimic specific processes in soil can be considered one of the most promising alternatives to overcome the difficulties behind the structural elucidation of riverine humic-derived iron-complexes. Herein, we propose that the immobilization of the functional mushroom tyrosinase, Agaricus bisporus Polyphenol Oxidase 4 (AbPPO4) on mesoporous SBA-15-type silica could contribute to the study of small aquatic humic ligands such as phenols. EXPERIMENTS: The silica support was functionalized with amino-groups in order to investigate the impact of surface charge on the tyrosinase loading efficiency as well as on the catalytic performance of adsorbed AbPPO4. The oxidation of various phenols was catalyzed by the AbPPO4-loaded bioconjugates, yielding high levels of conversion and confirming the retention of enzyme activity after immobilization. The structures of the oxidized products were elucidated by integrating chromatographic and spectroscopic techniques. We also evaluated the stability of the immobilized enzyme over a wide range of pH values, temperatures, storage-times and sequential catalytic cycles. FINDINGS: This is the first report where the latent AbPPO4 is confined within silica mesopores. The improved catalytic performance of the adsorbed AbPPO4 shows the potential use of these silica-based mesoporous biocatalysts for the preparation of a column-type bioreactor for in situ identification of soil samples.

Selective Discrimination between CO and H2 with Copper-Ceria-Resistive Gas Sensors.

The production of hydrogen and the utilization of biomass for sustainable concepts of energy conversion and storage require gas sensors that discriminate between hydrogen (H2) and carbon monoxide (CO). Mesoporous copper-ceria (Cu-CeO2) materials with large specific surface areas and uniform porosity are prepared by nanocasting, and their textural properties are characterized by N2 physisorption, powder XRD, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The oxidation states of copper (Cu+, Cu2+) and cerium (Ce3+, Ce4+) are investigated by XPS. The materials are used as resistive gas sensors for H2 and CO. The sensors show a stronger response to CO than to H2 and low cross-sensitivity to humidity. Copper turns out to be a necessary component; copper-free ceria materials prepared by the same method show only poor sensing performance. By measuring both gases (CO and H2) simultaneously, it is shown that this behavior can be utilized for selective sensing of CO in the presence of H2.

Temperature-Regulated Core Swelling and Asymmetric Shrinkage for Tunable Yolk@Shell Polydopamine@Mesoporous Silica Nanostructures.

Facile and controllable synthesis of functional yolk@shell structured nanospheres with a tunable inner core ('yolk') and mesoporous shell is highly desirable, yet it remains a great challenge. Herein, xx developed a strategy based on temperature-regulated swelling and restricted asymmetric shrinkage of polydopamine (PDA) nanospheres, combined with heterogeneous interface self-assembly growth. This method allows a simple and versatile preparation of PDA@mesoporous silica (MS) nanospheres exhibiting tunable yolk@shell architectures and shell pore sizes. Through reaction temperature-regulated swelling degree and confined shrinkage of PDA nanospheres, the volume ratio of the hollow cavity that the PDA core occupies can easily be tuned from ca. 2/3 to ca. 1/2, then to ca. 2/5, finally to ca. 1/3. Owing to the presence of PDA with excellent photothermal conversion capacity, the PDA@MS nanocomposites with asymmetric yolk distributions can become a colloidal nanomotor propelled by near-infrared (NIR) light. Noteworthily, the PDA@MS with half PDA yolk and microcracks in silica shell reaches 2.18 µm2 s-1 of effective diffusion coefficient (De) in the presence of 1.0 W cm-2 NIR light. This temperature-controlled swelling approach may provide new insight into the design and facile preparation of functional PDA-based yolk@shell structured nanocomposites for wide applications in biology and medicine.

Defect-Engineered Hydroxylated Mesoporous Spinel Oxides as Bifunctional Electrocatalysts for Oxygen Reduction and Evolution Reactions.

In this work, defect-rich ordered mesoporous spinel oxides, including CoCo2O4, NiCo2O4, and ZnCo2O4, were developed as bifunctional electrocatalysts toward oxygen reduction and evolution reactions (ORR and OER, respectively). The materials are synthesized via nanocasting and modified by chemical treatment with 0.1 M NaBH4 solution to enhance the defect concentration. The synthesized samples have metal and oxygen divacancies (VCo + VO) as the primary defect sites, as indicated by positron annihilation lifetime spectroscopy (PALS). Cation substitution in the spinel structure induces a higher number of oxygen vacancies. The increased number of surface defects and the synergistic effect between two incorporated metals provide a high activity in both the OER and ORR in the case of NiCo2O4 and ZnCo2O4. Especially, ZnCo2O4 exhibits the highest OER/ORR activity. The defect engineering with 0.1 M NaBH4 solution results in a metal-hydroxylated surface (M-OH) and enhanced the catalytic activity for the post-treated metal oxides in the ORR and OER. This fundamental investigation of the defective structure of the mixed metal oxides offers some useful insights into further development of highly active electrocatalysts through defect engineering methods.

Ultrathin Covalent Organic Framework Anchored on Graphene for Enhanced Organic Pollutant Removal.

Covalent organic frameworks (COFs) are of great potential as adsorbents owing to their tailorable functionalities, low density and high porosity. However, their intrinsically stacked two-dimensional (2D) structure limits the full use of their complete surface for sorption, especially the internal pores. The construction of ultrathin COFs could increase the exposure of active sites to the targeted molecules in a pollutant environment. Herein, an ultrathin COF with a uniform thickness of ca. 2 nm is prepared employing graphene as the surface template. The resulting hybrid aerogel with an ultralow density (7.1 mg cm-3 ) exhibits the ability to remove organic dye molecules of different sizes with high efficiency. The three-dimensional (3D) macroporous structure and well-exposed adsorption sites permit rapid diffusion of solution and efficient adsorption of organic pollutants, thereby, greatly contributing to its enhanced uptake capacity. This work highlights the effect of COF layer thickness on adsorption performance.

A perspective on developing solid-phase extraction technologies for industrial-scale critical materials recovery.

Critical materials (CMs) are a group of elements that have been determined to be important for the modern economy, but which may face current or potential supply limitations. Some examples of metals that have received the CM designation include the rare earth elements, indium, gallium, and lithium. The last decade has seen a major push for the development of new and improved technologies for the recovery and purification of CMs from various traditional and non-traditional resources in an effort to diversify supply. Solid-phase extraction (SPE) is one broad category of these experimental extraction technologies. SPE involves the application of a solid material to preferentially retain in the solid phase one or more specific components of an aqueous solution, leaving the other components behind in the aqueous phase. A wide range of different sorbents has been used for SPE, and many offer significant potential advantages, including low cost, low environmental impact, and high customizability. Hierarchically porous silica monoliths are one example of a cutting-edge sorbent that provides a durable, high surface area foundation that can be functionalized with a variety of targeted ligands for the selective extraction of specific CMs. Despite impressive recent advances in SPE, there remain areas for improvement that are common across the discipline. To demonstrate the practical viability of these innovative CM recovery systems, future SPE studies would benefit from devoting additional focus to the scalability of their material, as well as from focusing on real-world feedstocks and conducting techno-economic analyses and environmental impact studies.

A Covalent Organic Framework/Graphene Dual-Region Hydrogel for Enhanced Solar-Driven Water Generation.

Solar-driven water generation is a sustainable water treatment technology, helping to relieve global water scarcity issues. However, this technology faces great challenges due to the high energy consumption of water evaporation yielding low evaporation rates. Here, a covalent organic framework (COF)/graphene dual-region hydrogel, containing hydrophilic and hydrophobic regions in one material, is developed through a facile in situ growth strategy. The hydrophilic COF is covering parts of the hydrophobic graphene regions. Through accurate control of both wetting regions, the hybrid hydrogel shows effective light-harvesting, tunable wettability, optimized water content, and lowered energy demand for water vaporization. Acting as solar absorber, the dual-region hydrogel exhibits a steam generation rate as high as 3.69 kg m-2 h-1 under 1 sun irradiation (1 kW m-2), which competes well with other state-of-the-art materials. Furthermore, this hydrogel evaporator can be used to produce drinkable water from seawater and sewage, demonstrating the potential for water treatment.

Selective ligand removal to improve accessibility of active sites in hierarchical MOFs for heterogeneous photocatalysis.

Metal-organic frameworks (MOFs) are commended as photocatalysts for H2 evolution and CO2 reduction as they combine light-harvesting and catalytic functions with excellent reactant adsorption capabilities. For dynamic processes in liquid phase, the accessibility of active sites becomes a critical parameter as reactant diffusion is limited by the inherently small micropores. Our strategy is to introduce additional mesopores by selectively removing one ligand in mixed-ligand MOFs via thermolysis. Here we report photoactive MOFs of the MIL-125-Ti family with two distinct mesopore architectures resembling either large cavities or branching fractures. The ligand removal is highly selective and follows a 2-step process tunable by temperature and time. The introduction of mesopores and the associated formation of new active sites have improved the HER rates of the MOFs by up to 500%. We envision that this strategy will allow the purposeful engineering of hierarchical MOFs and advance their applicability in environmental and energy technologies.

Incorporation of Cu/Ni in Ordered Mesoporous Co-Based Spinels to Facilitate Oxygen Evolution and Reduction Reactions in Alkaline Media and Aprotic Li-O2 Batteries.

Ordered mesoporous CuNiCo oxides were prepared via nanocasting with varied Cu/Ni ratio to establish its impact on the electrochemical performance of the catalysts. Physicochemical properties were determined along with the electrocatalytic activities toward oxygen evolution/reduction reactions (OER/ORR). Combining Cu, Ni, and Co allowed creating active and stable bifunctional electrocatalysts. CuNiCo oxide (Cu/Ni≈1 : 4) exhibited the highest current density of 411 mA cm-2 at 1.7 V vs. reversible hydrogen electrode (RHE) and required the lowest overpotential of 312 mV to reach 10 mA cm-2 in 1 m KOH after 200 cyclic voltammograms. OER measurements were also conducted in the purified 1 m KOH, where CuNiCo oxide (Cu/Ni≈1 : 4) also outperformed NiCo oxide and showed excellent chemical and catalytic stability. For ORR, Cu/Ni incorporation provided higher current density, better kinetics, and facilitated the 4e- pathway of the oxygen reduction reaction. The tests in Li-O2 cells highlighted that CuNiCo oxide can effectively promote ORR and OER at a lower overpotential.

A Biomimetic, Silaffin R5-Based Antigen Delivery Platform.

Nature offers a wide range of evolutionary optimized materials that combine unique properties with intrinsic biocompatibility and that can be exploited as biomimetic materials. The R5 and RRIL peptides employed here are derived from silaffin proteins that play a crucial role in the biomineralization of marine diatom silica shells and are also able to form silica materials in vitro. Here, we demonstrate the application of biomimetic silica particles as a vaccine delivery and adjuvant platform by linking the precipitating peptides R5 and the RRIL motif to a variety of peptide antigens. The resulting antigen-loaded silica particles combine the advantages of biomaterial-based vaccines with the proven intracellular uptake of silica particles. These particles induce NETosis in human neutrophils as well as IL-6 and TNF-α secretion in murine bone marrow-derived dendritic cells.

Evaporation-Induced Self-Assembly of Small Peptide-Conjugated Silica Nanoparticles.

Self-assembly processes guide disordered molecules or particles into long-range organized structures due to specific supramolecular interactions among the building entities. Herein, we report a unique evaporation-induced self-assembly (EISA) strategy for four different silica nanoparticle systems obtained through peptide functionalization of the particle surface. First, covalent peptide-silica coupling was investigated in detail, starting with the grafting of a single amino acid (L-serine) and expanded to specific small peptides (up to four amino acids) and transferred to different particle types (MCM-48-type MSNs, solid nanoparticles, and newly developed virus-like nanoparticles). These materials were investigated regarding their ability to undergo EISA, which was shown to be independent of particle type and amount of peptide anchored to their surface. This EISA-based approach provides new possibilities for the design of future advanced drug delivery systems, engineered hierarchical sorbents, and nanocatalyst assemblies.