Search results for "silicon dioxide"
showing 10 items of 278 documents
A Sensitive Nanosensor for the In Situ Detection of the Cannibal Drug.
2020
[EN] A bio-inspired nanodevice for the selective and sensitive fluorogenic detection of 3,4- methylenedioxypyrovalerone (MDPV), usually known as Cannibal drug, is reported. The sensing nanodevice is based on mesoporous silica nanoparticles (MSNs), loaded with a fluorescent reporter (rhodamine B) and functionalized on their external surface with a dopamine derivative (3), which specifically interacts with the recombinant human dopamine transporter (DAT), capping the pores. In the presence of MDPV, DAT detaches from the MSNs consequently causing rhodamine B release and allowing drug detection. The nanosensor shows a detection limit of 5.2 µM and it is able to detect the MDPV drug both in sali…
Role of murine macrophages and complement in experimental campylobacter infection
1988
Summary. The roles of macrophages and the complement system as potential host defence mechanisms in mice against campylobacter infection were studied in vivo, by depleting the murine serum-complement or the phagocytic cells. Macrophage-depletion was performed by intraperitoneal (i.p.) injection of silica dust, Liquoid or dextran sulphate. During 5 days after infection, such mice showed a significant increase in mortality, compared with controls. In contrast, mice that were previously decomplemented by i.p. injection of Cobra Venom Factor showed no significant increase in mortality. The results with combined macrophage depletion and decomplementation did not differ from those with macrophage…
Hemocyanin from E. californicum encapsulated in silica gels: oxygen binding and conformational states.
2007
Cooperativity depends on the existence of equilibria among functionally distinct conformational states that are affected by homo and heterotropic effectors. In order to isolate the quaternary conformations of hemocyanin from E. californicum, the 24-meric giant protein was encapsulated in wet, nanoporous silica gels, either in the absence or presence of oxygen. The deoxy- and oxy-hemocyanin gels exhibit a p50 for oxygen of 11 and 2.5 torr, respectively, values in close agreement with those for hemocyanin in solution. The observed Hill coefficients are lower than unity, indicating a conformational heterogeneity within each locked conformational state, a finding in agreement with the assumptio…
Fractal-related assembly of the axial filament in the demosponge Suberites domuncula: relevance to biomineralization and the formation of biogenic si…
2007
Abstract The siliceous spicules of sponges (Porifera) show great variations of sizes, shapes and forms; they constitute the chief supporting framework of these animals; these skeletal elements are synthesized enzymatically by silicatein. Each sponge species synthesizes at least two silicateins, which are termed − α and − β . In the present study, using the demosponge Suberites domuncula , we studied if the silicateins of the axial filament contribute to the shape formation of the spicules. For these experiments native silicateins have been isolated by a new Tris/glycerol extraction procedure. Silicateins isolated by this procedure are monomeric (24 kDa), but readily form dimers through non-…
Controlled release using mesoporous materials containing gate-like scaffoldings.
2009
The use of gated mesoporous silica solids as suitable systems for controlled-release protocols is reviewed. These materials are based on mesoporous silica supports that can be prepared with tailor-made pores of around 2 - 10 nm and that show a very large specific surface area (up to 1200 m(2)/g), thus having a large load capacity. The solids can be additionally functionalised in the external surface with gate-like systems that can be opened on command to allow cargo release. Light, redox reactions, pH, temperature, polarity and enzyme-driven protocols are shown. The possible application in drug delivery protocols is discussed.
Finely Tuned Temperature-Controlled Cargo Release Using Paraffin-Capped Mesoporous Silica Nanoparticles
2011
[EN] Trapped: Mesoporous silica nanoparticles were loaded with a fluorescent guest and functionalized with octadecyltrimethoxysilane. The alkyl chains interact with paraffins, which build a hydrophobic layer around the particle (see picture). Upon melting of the paraffin, the guest molecule is released, as demonstrated in cells for the guest doxorubicin. The release temperature can be tuned by choosing an appropriate paraffin. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Temperature-controlled release by changes in the secondary structure of peptides anchored onto mesoporous silica supports
2014
Changes in the conformation of a peptide anchored onto the external surface of mesoporous silica nanoparticles have been used to design novel temperature-controlled delivery systems.
The amorphous silica-liquid water interface studied by ab initio molecular dynamics (AIMD): local organization in global disorder
2014
International audience; The structural organization of water at a model of amorphous silica-liquid water interface is investigated by ab initio molecular dynamics (AIMD) simulations at room temperature. The amorphous surface is constructed with isolated, H-bonded vicinal and geminal silanols. In the absence of water, the silanols have orientations that depend on the local surface topology (i.e. presence of concave and convex zones). However, in the presence of liquid water, only the strong inter-silanol H-bonds are maintained, whereas the weaker ones are replaced by H-bonds formed with interfacial water molecules. All silanols are found to act as H- bond donors to water. The vicinal silanol…
Bioinspired manganese(II) complexes with a clickable ligand for immobilisation on a solid support.
2014
International audience; Clickable ligands like N,N′-bis((pyridin-2-yl)methyl)prop-2-yn-1-amine (L1) and N-((1-methyl-1H-imidazol-2-yl)methyl)-N-(pyridin-2-ylmethyl)prop-2-yn-1-amine (L2) have been used to synthesise a series of manganese(II) complexes for grafting onto appropriate solid supports. These ligands mimic the 2-His-1-carboxylate facial chelation present in the active site of the manganese-dependent dioxygenase (MndD), while the alkyne side function allows grafting of the ligand onto an azido-functionalised support using “click chemistry” methodologies. Such synthetic analogues of the MndD crystallise in the solid state as double halide or pseudohalide-bridged dinuclear manganese(…
Delivery modulation in silica mesoporous supports via alkyl chain pore outlet decoration
2012
This article focuses on the study of the release rate in a family of modified silica mesoporous supports. A collection of solids containing ethyl, butyl, hexyl, octyl, decyl, octadecyl, docosyl, and triacontyl groups anchored on the pore outlets of mesoporous MCM-41 has been prepared and characterized. Controlled release from pore voids has been studied through the delivery of the dye complex tris(2,2¿-bipyridyl)ruthenium(II). Delivery rates were found to be dependent on the alkyl chain length anchored on the pore outlets of the mesoporous scaffolding. Moreover, release rates follow a Higuchi diffusion model, and Higuchi constants for the different hybrid solids have been calculated. A decr…