Langmuir最新文献

Amino-functionalized silica has attracted a great deal of interest due to its high surface reactivity and potential for diverse applications across various fields. While the classical co-condensation method is commonly used to synthesize amino-functionalized silica particles, the mechanism of the reaction between (3-aminopropyl)triethoxysilane (APTES) and tetraethoxysilane under different conditions remains unclear, leading to unexpected self-nucleation or cross-linking between silica particles and consequently hindering rational control over the extent of functionalization. To address this issue, we systematically explored the co-condensation growth mechanism of amino-functionalized silica particles in the Stöber method by investigating the effects of APTES concentration and water content on the hydrolysis and condensation of silanes. The experimental results revealed that APTES could decrease the rate of hydrolysis/condensation, while the moderate water content promoted both the rate of hydrolysis/condensation and the overall quality of the silica particles. Consequently, we successfully demonstrated the rational synthesis of amino-functionalized silica particles with diameters ranging from 213 to 670 nm and a nitrogen content of ≤2.8 wt %. The relationship between the APTES concentration and particle properties exhibited a biphasic trend. At low APTES concentrations (≤2.0 mM), the particle size remained stable while the isoelectric point increased rapidly. Further increasing the APTES concentration from 2.0 to 100.0 mM induced a decrease in particle size due to APTES's inhibitory effect on silica growth, with nitrogen content continuing to increase even after the isoelectric point remained unchanged. These silica particles, featuring varying surface amino group densities, were utilized as matrices for loading Au nanoparticles. The resulting functionalized particles exhibited distinctive catalytic ability in the reduction of 4-nitroaniline, demonstrating significant potential for applications across various fields.

Nanostructured particles (NSPs), with their remarkable properties at the nanoscale, possess key functions required for unlocking a sustainable future. Fabricating these particles using aerosol methods and spraying processes enables precise control over the particle morphology, structure, composition, and crystallinity during in-flight transformation. In this Perspective, the significant impact of NSPs on technological advancement for energy and environmental applications is discussed. Furthermore, incorporating in situ/operando assessment techniques alongside machine and deep learning is explored. Finally, the future development trends and the perspective on the advancing NSPs synthesis via aerosol process are elaborated for further driving innovations for supersmart and carbon-neutral society.

Catalytic transfer hydrogenation (CTH) using Cu nanocatalysts offers significant advantages over direct high-pressure hydrogenation. However, the active hydrogen (H*) in this process exhibits poor adsorption and tends to release H₂ readily due to the fully occupied 3d states of Cu. To address this issue, a tubular SnO₂ support with electron-accepting ability was selected to host Cu nanoparticles, aiming to optimize the Cu 3d bands. The Cu/SnO₂ nanohybrids were prepared through an electrospinning technique, followed by hydrothermal synthesis. As evidenced by X-ray photoelectron spectroscopy (XPS) binding energy shifts and density functional theory (DFT) simulations, some electrons from Cu transferred to SnO₂ in the Cu/SnO₂ nanohybrids due to their different work functions. Such electron transfer enables the Cu 3d orbitals to lose electrons and alters its valence configuration from 3d¹⁰ to 3d^10-x, which enhances the adsorption of active H* atoms and thereby inhibits undesirable H₂ release. The 15 wt % Cu/SnO₂ exhibits improved catalytic hydrogenation of 4-nitrophenol with NaBH₄, with an optimal normalized rate constant of 56.98 mg^-1 min^-1 and a turnover frequency of 4.82 min^-1, surpassing most reported catalysts. The enhanced activity is attributed to the optimized electronic states, improved hydrogen adsorption, and the tubular structure of the support. This work might shed light on developing more non-noble metal nanocatalysts for CTH by tuning their d bands with appropriate oxide supports.

Dimethyldichlorosilane (DMDCS), an efficient silane coupling reagent appearing between the -OH groups of silica gel (SG) and picric acid, instantaneously produces a derivative enriched with nitro groups. The nitro group acting as an end-cap terminates the reaction and subsequently was converted into diazo to couple tyrosine's phenol ring via its O-carbon, the inert center to immobilize horseradish peroxidase (HRP) in a multipoint mode. It maintains the status quo of the native enzyme's protein folding and the entire protein groups' chemistry. The molecular formula of the synthesized material was verified and appeared as {Si(OSi)₄ (H₂O)_x}_n{-O-Si(CH₃)₂-O-C₆H₂(N⁺≡N)₃(HRP)}₄·yH₂O; the parameters were evaluated as x = 0.5, n = 1158, and y = 752. The immobilized biocatalyst's activity in organic solvents was 1.5 times better than that in an aqueous medium; it worked smoothly, wherein the activity in both solvents stabilized at six months and continued up to nine months at 63 ± 3% compared to the initial.

Understanding how the spatial distribution of adhesive ligands regulates cell behavior is crucial for designing biomaterials. This study investigates how precisely controlled ligand spacing affects cell spreading and integrin subtype engagement. Using engineered polyacrylamide hydrogels with gold nanoparticle arrays, we explored the impact of RGD ligand spacings (30 and 150 nm) on human mesenchymal stromal cells. Cells exhibited distinct morphological behaviors: smaller spacings promoted larger spreading areas, while larger spacings resulted in elongated shapes with reduced spreading. Mechanistically, we found that the α₅β₁ integrin, not the α_vβ₃ integrin, played a central role in mediating these responses, alongside lamellipodia formation. Our findings provide critical insights into the spatial sensing of ligands, highlighting the influence of ligand spacing on cellular mechanotransduction and integrin-specific responses. This work advances the understanding of cell-material interactions and offers potential strategies for designing biomaterials to guide cell behavior in tissue engineering.

In practical applications of surface-modified nanoparticles (NPs), the washing stage has a number of challenges, such as insufficient washing, long treatment time, and various waste liquors. Cosolvent-enhanced supercritical CO₂ (scCO₂) is an appealing solvent system for complete, rapid, and eco-friendly washing owing to its high diffusivity and recyclability. In this paper, we report a rapid washing guideline for surface-modified NPs using ethanol-enhanced scCO₂. Kinetic analysis was performed on the washing behavior of oleic acid-modified NPs mixed with various modifiers (C10 to C18 fatty acids) at 40 °C and 20.0 MPa while designing scCO₂ media based on rationally estimated modifier solubilities. Notably, the scCO₂ medium showed superior washing rates to that of ethanol for various modifiers with a wide range of solubilities in scCO₂. The washing rate was dependent on solubility and could be organized into two regions, with a threshold value of 0.016 mol kg^-1: solubility/diffusivity-controlled and diffusivity-controlled washing. These findings provide valuable guidelines for designing cosolvent-enhanced scCO₂ media for the rapid washing of surface-modified NPs.