Browse
Submit Data
Databases
API
Help

Dataset Information

25 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Pore Narrowing of Mesoporous Silica Materials.

ABSTRACT: To use mesoporous silicas as low-k materials, the pore entrances must be really small to avoid diffusion of metals that can increase the dielectric constant of the low-k dielectric. In this paper we present a new method to narrow the pores of mesoporous materials through grafting of a cyclic-bridged organosilane precursor. As mesoporous material, the well-studied MCM-41 powder was selected to allow an easy characterization of the grafting reactions. Firstly, the successful grafting of the cyclic-bridged organosilane precursor on MCM-41 is presented. Secondly, it is demonstrated that pore narrowing can be obtained without losing porosity by removing the porogen template after grafting. The remaining silanols in the pores can then be end-capped with hexamethyl disilazane (HMDS) to make the material completely hydrophobic. Finally, we applied the pore narrowing method on organosilica films to prove that this method is also successful on existing low-k materials.

SUBMITTER: Goethals F

PROVIDER: S-EPMC5452099 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Highly aminated mesoporous silica nanoparticles with cubic pore structure.

Project description:Mesoporous silica with cubic symmetry has attracted interest from researchers for some time. Here, we present the room temperature synthesis of mesoporous silica nanoparticles possessing cubic Pm3n symmetry with very high molar ratios (>50%) of 3-aminopropyl triethoxysilane. The synthesis is robust allowing, for example, co-condensation of organic dyes without loss of structure. By means of pore expander molecules, the pore size can be enlarged from 2.7 to 5 nm, while particle size decreases. Adding pore expander and co-condensing fluorescent dyes in the same synthesis reduces average particle size further down to 100 nm. After PEGylation, such fluorescent aminated mesoporous silica nanoparticles are spontaneously taken up by cells as demonstrated by fluorescence microscopy.

| S-EPMC3084371 | biostudies-literature

Size-selective pH-operated megagates on mesoporous silica materials.

Project description:pH-responsive megagates have been fabricated around mesoporous silica material SBA-15 in order to mechanize the mesopores. These megagates remain closed in neutral conditions, but open at pH 5. The capping components of the megagates were designed to be capable of controlling pores up to 6.5 nm in diameter. Selectivity of payloads with different sizes can be achieved through the use of different capping components. The operation of the megagates was demonstrated by time-resolved fluorescence spectroscopy which is capable of monitoring the release of both the payload and the cap. This study opens up new possibilities in the field of controllable release.

| S-EPMC3884833 | biostudies-literature

Mesoporous Silica and Titania-Based Materials for Stability Enhancement of Polyphenols.

Project description:To improve phytochemical stability, polyphenolic extracts prepared from Salvia officinalis L., which is a valuable source of phytocompounds with health benefits, were embedded into mesopores of silica, titania, or titania-ceria materials. Ethanolic and hydroalcoholic extracts were prepared by conventional, microwave- or ultrasound-assisted extraction. The influence of the extraction conditions on chemical profile, radical scavenger activity (RSA), and antimicrobial potential of the extracts was assessed. The extracts were characterized by spectrophotometric determination of total polyphenols, flavonoids, chlorophyll pigment contents, as well as RSA. A reverse phase HPLC- PDA analysis was performed for the identification and quantification of extract polyphenols. The extract-loaded materials exhibited an enhanced RSA compared to the free extract after several months of storage, resulting in better polyphenol stability over time following embedding into a mesoporous matrix. Selected extracts free and embedded into mesoporous support were tested against Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, and Staphylococcus aureus ATCC 25923; the best antimicrobial activity was obtained for S. aureus. A slight improvement in antimicrobial activity was observed for the ethanolic extract prepared by ultrasound-assisted extraction following embedding into the TiO2 matrix compared to MCM-41 silica due to the support contribution.

| S-EPMC8585155 | biostudies-literature

The pore size of mesoporous silica nanoparticles regulates their antigen delivery efficiency.

Project description:Subunit vaccines generally proceed through a 4-step in vivo cascade-the DUMP cascade-to generate potent cell-mediated immune responses: (1) drainage to lymph nodes; (2) uptake by dendritic cells (DCs); (3) maturation of DCs; and (4) Presentation of peptide-MHC I complexes to CD8+ T cells. How the physical properties of vaccine carriers such as mesoporous silica nanoparticles (MSNs) influence this cascade is unclear. We fabricated 80-nm MSNs with different pore sizes (7.8 nm, 10.3 nm, and 12.9 nm) and loaded them with ovalbumin antigen. Results demonstrated these MSNs with different pore sizes were equally effective in the first three steps of the DUMP cascade, but those with larger pores showed higher cross-presentation efficiency (step 4). Consistently, large-pore MSNs loaded with B16F10 tumor antigens yielded the strongest antitumor effects. These results demonstrate the promise of our lymph node-targeting large-pore MSNs as vaccine-delivery vehicles for immune activation and cancer vaccination.

| S-EPMC7304990 | biostudies-literature

Adsorption-Induced Deformation of Hierarchically Structured Mesoporous Silica-Effect of Pore-Level Anisotropy.

Project description:The goal of this work is to understand adsorption-induced deformation of hierarchically structured porous silica exhibiting well-defined cylindrical mesopores. For this purpose, we performed an in situ dilatometry measurement on a calcined and sintered monolithic silica sample during the adsorption of N2 at 77 K. To analyze the experimental data, we extended the adsorption stress model to account for the anisotropy of cylindrical mesopores, i.e., we explicitly derived the adsorption stress tensor components in the axial and radial direction of the pore. For quantitative predictions of stresses and strains, we applied the theoretical framework of Derjaguin, Broekhoff, and de Boer for adsorption in mesopores and two mechanical models of silica rods with axially aligned pore channels: an idealized cylindrical tube model, which can be described analytically, and an ordered hexagonal array of cylindrical mesopores, whose mechanical response to adsorption stress was evaluated by 3D finite element calculations. The adsorption-induced strains predicted by both mechanical models are in good quantitative agreement making the cylindrical tube the preferable model for adsorption-induced strains due to its simple analytical nature. The theoretical results are compared with the in situ dilatometry data on a hierarchically structured silica monolith composed by a network of mesoporous struts of MCM-41 type morphology. Analyzing the experimental adsorption and strain data with the proposed theoretical framework, we find the adsorption-induced deformation of the monolithic sample being reasonably described by a superposition of axial and radial strains calculated on the mesopore level. The structural and mechanical parameters obtained from the model are in good agreement with expectations from independent measurements and literature, respectively.

| S-EPMC5484557 | biostudies-literature

New Generation of Mesoporous Silica Membranes Prepared by a Stober-Solution Pore-Growth Approach.

Project description:Membranes consisting of uniform and vertically organized mesopores are promising systems for molecular filtration because of the possibility to combine high-flux and high-rejection properties. In this work, a new generation of mesoporous silica membranes (MSMs) have been developed, in which an organized mesoporous layer is directly formed on top of a porous ceramic support via a Stöber-solution pore-growth approach. Relevant characterization methods have been used to demonstrate the growth of the membrane separation layer and the effect of reaction time and the concentration of the reactants on the microstructure of the membrane. Compared to previous studies using the evaporation-induced self-assembly method to prepare MSMs, an important increase in water permeability was observed (from 1.0 to at least 3.8 L m-2 h-1 bar-1), indicating an improved pore alignment. The water permeability, cyclohexane permporometry tests, and molecular cut-off measurements (MWCO ≈ 2300 Da) were consistent with membranes composed of 2-3 nm accessible pores.

| S-EPMC6533597 | biostudies-literature

Isolation and immobilization of alkaline protease on mesoporous silica and mesoporous ZSM-5 zeolite materials for improved catalytic properties.

Project description:Alkaline protease from brinjal leaf (Solanum melongena) having milk clotting activity has been purified to 9.44 fold to a final specific activity of 45.71 U/mg. SDS-PAGE of the final preparation revealed a single protein band of approx 14 kDa. Purified enzyme was characterized and was successfully immobilized into the amorphous mesoporous silica (SBA-15) and crystalline mesoporous zeolite (Nano-ZSM-5) using entrapment method. Maximum immobilization of 63.5% and 79.77% was obtained with SBA-15 and Nano-ZSM-5, respectively. This protocol serves as a novel approach for bioprocesses, mainly as milk coagulant for local dairy products and particularly, cheese making, and opens the new dimension of further research and other innovation.

| S-EPMC5668643 | biostudies-literature

Single Crystal FLIM Characterization of Clofazimine Loaded in Silica-Based Mesoporous Materials and Zeolites.

Project description:Clofazimine (CLZ) is an effective antibiotic used against a wide spectrum of Gram-positive bacteria and leprosy. One of its main drawbacks is its poor solubility in water. Silica based materials are used as drug delivery carriers that can increase the solubility of different hydrophobic drugs. Here, we studied how the properties of the silica framework of the mesoporous materials SBA-15, MCM-41, Al-MCM-41, and zeolites NaX, NaY, and HY affect the loading, stability, and distribution of encapsulated CLZ. Time-correlated single-photon counting (TCSPC) and fluorescence lifetime imaging microscopy (FLIM) experiments show the presence of neutral and protonated CLZ (1.3-3.8 ns) and weakly interacting aggregates (0.4-0.9 ns), along with H- and J-type aggregates (<0.1 ns). For the mesoporous and HY zeolite composites, the relative contribution to the overall emission spectra from H-type aggregates is low (<10%), while for the J-type aggregates it becomes higher (~30%). For NaX and NaY the former increased whereas the latter decreased. Although the CLZ@mesoporous composites show higher loading compared to the CLZ@zeolites ones, the behavior of CLZ is not uniform and its dynamics are more heterogeneous across different single mesoporous particles. These results may have implication in the design of silica-based drug carriers for better loading and release mechanisms of hydrophobic drugs.

| S-EPMC6627708 | biostudies-literature

Large Pore Mesoporous Silica and Organosilica Nanoparticles for Pepstatin A Delivery in Breast Cancer Cells.

Project description:(1) Background: Nanomedicine has recently emerged as a new area of research, particularly to fight cancer. In this field, we were interested in the vectorization of pepstatin A, a peptide which does not cross cell membranes, but which is a potent inhibitor of cathepsin D, an aspartic protease particularly overexpressed in breast cancer. (2) Methods: We studied two kinds of nanoparticles. For pepstatin A delivery, mesoporous silica nanoparticles with large pores (LPMSNs) and hollow organosilica nanoparticles (HOSNPs) obtained through the sol?gel procedure were used. The nanoparticles were loaded with pepstatin A, and then the nanoparticles were incubated with cancer cells. (3) Results: LPMSNs were monodisperse with 100 nm diameter. HOSNPs were more polydisperse with diameters below 100 nm. Good loading capacities were obtained for both types of nanoparticles. The nanoparticles were endocytosed in cancer cells, and HOSNPs led to the best results for cancer cell killing. (4) Conclusions: Mesoporous silica-based nanoparticles with large pores or cavities are promising for nanomedicine applications with peptides.

| S-EPMC6359328 | biostudies-literature

Nanometer-thick conformal pore sealing of self-assembled mesoporous silica by plasma-assisted atomic layer deposition.

Project description:On a porous substrate, regular atomic layer deposition (ALD) not only takes place on top of the substrate but also penetrates into the internal porosity. Here we report a plasma-assisted process in which the ALD precursors are chosen to be nonreactive unless triggered by plasma, so that ALD can be spatially defined by the supply of plasma irradiation. Since plasma cannot penetrate within the internal porosity, ALD has been successfully confined to the immediate surface. This not only gives a possible solution for sealing of porous low dielectric constant films with a conformal layer of nm-scale thickness but also enables us to progressively reduce the pore size of mesoporous materials in a sub-A/cycle fashion for membrane formation.

| S-EPMC2707262 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data