Modulation of folic acid bioaccessibility by encapsulation in pH-responsive gated mesoporous silica particles
[EN] A study on the controlled release of folic acid (FA) from pH-responsive gated mesoporous silica particles (MSP) is reported. The MCM-41 support was synthesized using tetraethyl orthosilicate (TEOS) as hydrolytic inorganic precursor and the surfactant hexadecyltrimethylammonium bromide (CTAB) as porogen species. Calcination of the mesostructured phase resulted in the starting solid. This solid was loaded with FA to obtain the initial support S0. Moreover, this FA-loaded material was further functionalized with 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (N3) in order to obtain the gated polyamine-functionalised material S1. Solids S0 and S1 were characterized using standar…
Nanoscopic hybrid systems with a polarity-controlled gate-like scaffolding for the colorimetric signalling of long-chain carboxylates
Hybrid mesoporous systems containing a gate-like ensemble functionalised with imidazolium groups and a dye are used for the selective colorimetric sensing of long-chain carboxylates. Amoros del Toro, Pedro Jose, Pedro.Amoros@uv.es
Full inhibition of enzymatic browning in the presence of thiol-functionalised silica nanomaterial
[EN] Darkening processed fruits and vegetables is caused mainly by enzymatic browning through polyphenol oxidase (PPO) action. Accordingly, we explored the potential of four silica-based materials (MCM-41 nanometric size, MCM-41 micrometric size, UVM-7 and aerosil), non-functionalised and functionalised with thiol groups, to inhibit PPO activity in the model system and apple juice. All materials showed relevant performance when immobilising and inhibiting PPO in model systems, and support topology is a main factor for enzyme immobilisation and inhibition. Thiol-containing silica UVM7-SH showed the greatest inactivation, and similar browning values to those obtained by acidification. The enz…
Enzyme-Mediated Controlled Release Systems by Anchoring Peptide Sequences on Mesoporous Silica Supports
[EN] Gated community: Peptides anchored to the surface of silica mesoporous supports by a valid procedure act as gatekeepers. In this way, "zero release" supports that selectively deliver the cargo in the presence of a suitable peptidase are obtained (see picture, red spheres: cargo, colored chains: peptides). © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Cathepsin-B Induced Controlled Release from Peptide-Capped Mesoporous Silica Nanoparticles
New capped silica mesoporous nanoparticles for intracellular controlled cargo release within cathepsin B expressing cells are described. Nanometric mesoporous MCM-41 supports loaded with safranin O (S1-P) or doxorubicin (S2-P) containing a molecular gate based on a cathepsin B target peptidic sequence were synthesized. Solids were designed to show "zero delivery" and to display cargo release in the presence of cathepsin B enzyme, which selectively hydrolyzed in vitro the capping peptide sequence. Controlled delivery in HeLa, MEFs WT, and MEFs lacking cathepsin B cell lines were also tested. Release of safranin O and doxorubicin in these cells took place when cathepsin B was active or presen…
Borate-driven gatelike scaffolding using mesoporous materials functionalised with saccharides.
We report the development of an MCM-41 mesoporous support that is functionalised with saccharides at the pore outlets and contains the dye [Ru(bipy)(3)](2+) in the pores (solid S1; bipy = 2,2'-bipyridyl). For this hybrid system, the inhibition of mass transport of the dye from the pore voids to the bulk solution in the presence of borate is demonstrated in water at neutral pH. The formation of the corresponding boroester derivative is related to the selective reaction of borate with the appended saccharides. This control is selective and only anion borate, among several anions and cations, can act as a molecular tap and inhibit the delivery of the entrapped guest. Additionally, the S1-borat…
Functional Magnetic Mesoporous Silica Microparticles Capped with an Azo-Derivative: A Promising Colon Drug Delivery Device
[EN] Magnetic micro-sized mesoporous silica particles were used for the preparation of a gated material able to release an entrapped cargo in the presence of an azo-reducing agent and, to some extent, at acidic pH. The magnetic mesoporous microparticles were loaded with safranin O and the external surface was functionalized with an azo derivative 1 (bearing a carbamate linkage) yielding solid S1. Aqueous suspensions of S1 at pH 7.4 showed negligible safranin O release due to the presence of the bulky azo derivative attached onto the external surface of the inorganic scaffold. However, in the presence of sodium dithionite (azoreductive agent), a remarkable safranin O delivery was observed. A…
Dual Enzyme-Triggered Controlled Release on Capped Nanometric Silica Mesoporous Supports
The development of nanoscopic hybrid materials equipped with “molecular gates” showing the ability of releasing target entrapped guests upon the application of an external trigger has attracted great attention and has been extensively explored during recent years.1 These nanodevices are composed of two subunits, namely, a suitable support and certain capping entities grafted on the surface of the scaffolding.2 The support is used as a suitable reservoir in which certain chemicals can be stored whereas the molecules grafted in the outer surface act as a “gate” and can control the release of the entrapped molecules at will. Both components are carefully selected and arranged in order to achie…
Caspase 3 Targeted Cargo Delivery in Apoptotic Cells Using Capped Mesoporous Silica Nanoparticles
[EN] Excessive apoptotic cell death is at the origin of several pathologies, such as degenerative disorders, stroke or ischemia-reperfusion damage. In this context, strategies to improve inhibition of apoptosis and other types of cell death are of interest and may represent a pharmacological opportunity for the treatment of cell-death-related disorders. In this scenario new peptide-containing delivery systems (solids S1-P1and S1-P2) are described based on meso-porous silica nanoparticles (MSNs) loaded with a dye and capped with the KKGDEVDKKARDEVDK (P1) peptide that contains two repeats of the DEVD target sequence that are selectively hydrolyzed by caspase3 (C3). This enzyme plays a central…
An aptamer-gated silica mesoporous material for thrombin detection.
An aptamer-capped mesoporous material for the selective and sensitive detection of &-thrombin in human plasma and serum has been prepared and characterised.
Design of enzyme-mediated controlled release systems based on silica mesoporous supports capped with ester-glycol groups
[EN] An ethylene glycol-capped hybrid material for the controlled release of molecules in the presence of esterase enzyme has been prepared. The final organic-inorganic hybrid solid S1 was synthesized by a two-step procedure. In the first step, the pores of an inorganic MCM-41 support (in the form of nanoparticles) were loaded with [Ru(bipy) 3]Cl 2 complex, and then, in the second step, the pore outlets were functionalized with ester glycol moieties that acted as molecular caps. In the absence of an enzyme, release of the complex from aqueous suspensions of S1 at pH 8.0 is inhibited due to the steric hindrance imposed by the bulky ester glycol moieties. Upon addition of esterase enzyme, del…
Fatty Acid Carboxylate- and Anionic Surfactant-Controlled Delivery Systems That Use Mesoporous Silica Supports
We report the preparation of a MCM-41 mesoporous material that contains the dye [Ru(bipy) 3 ]Cl 2 (bipy= bipyridine) inside the mesopores and functionalised with suitable binding groups at the entrance of the pores. Solids S1―S3 were obtained by the reaction of the mesoporous material with N-methyl-N'-propyltrimethoxysilylimidazolium chloride, N-phenyl-N'-[3-(trimethoxysilyl)propyl]thiourea, or N-phenyl-N'-[3-(trimethoxysilyl)propy1]urea, respectively. A study of the dye delivery of these systems in buffered water (pH 7.0, 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid (HEPES), 10 ―3 mol dm ―3 ) in the presence of a family of carboxylate ions was carried out. In the interaction of …
A Mesoporous 3D Hybrid Material with Dual Functionality for Hg2+Detection and Adsorption
Dual-function hybrid material U1 was designed for simultaneous chromofluorogenic detection and removal of Hg(2+) in an aqueous environment. Mesoporous material UVM-7 (MCM41 type) with homogeneously distributed pores of about 2-3 nm in size, a large specific surface area exceeding 1000 m(2) g(-1), and nanoscale particles was used as an inorganic support. The mesoporous solid is decorated with thiol groups that were treated with squaraine dye III to give a 2,4-bis(4-dialkylaminophenyl)-3-hydroxy-4-alkylsulfanylcyclobut-2-enone (APC) derivative that is covalently anchored to the inorganic silica matrix. The solid was characterised by various techniques including X-ray diffraction, transmission…