Search results for "SURFACE MODIFICATION"
showing 10 items of 417 documents
Site-specific halloysite functionalization by polydopamine: A new synthetic route for potential near infrared-activated delivery system
2022
Abstract Halloysite nanotubes (HNTs) represent a versatile core structure for the design of functional nanosystems of biomedical interest. However, the development of selective methodologies for the site-controlled functionalization of the nanotubes at specific sites is not an easy task. This study aims to accomplish a procedure for the site-selective/specific, “pin-point”, functionalization of HNTs with polydopamine (HNTs@PDA). This goal was achieved, at pH 6.5, by exploiting the basicity of ZnO nanoparticles anchored on the HNTs external surface (HNTs@ZnO) to induce a punctual polydopamine polymerization and coating. The morphology and the chemical composition of the nanomaterial was demo…
Modulation of folic acid bioaccessibility by encapsulation in pH-responsive gated mesoporous silica particles
2015
[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…
Low-cost materials for boron adsorption from water
2012
[EN] Knowing the affinity of boron aqueous species for cis-diol organic groups, five different hybrid materials have been prepared by anchoring glucose groups onto the surface of silica matrices with a different surface topology: UVM-7 bimodal mesoporous silica, UVM-11 unimodal non-templated mesoporous silica, commercial silica fume and two silica xerogels with pores within the mesoporous range (13-50 nm). After optimizing the experimental conditions, a comparison was made of the boron adsorption capacities in water. The relationship of the structural and functionalization parameters is discussed and the importance of the surface topology in the final adsorption behaviour is revealed. Hence…
Stability of different mesoporous silica particles during an in vitro digestion
2016
Mesoporous silica materials have the ability to entrap drugs, nutrients and functional biomolecules and can be able to act as smart delivery systems capable to control and target the release of their cargo in a particular part of the gastrointestinal tract when administrated orally. However, the aptness of these encapsulation supports in in vivo oral controlled release relies on their chemical stability through the digestive tube. In this context, we have evaluated the stability of four different mesoporous silica particles, frequently used as encapsulating supports, during an in vitro digestion process comprising buccal, stomach and intestinal phases. Results showed that after 4 h of diges…
Palladium-catalyzed dehydrogenative β'-functionalization of β-keto esters with indoles at room temperature.
2012
The dehydrogenative β′-functionalization of α-substituted β-keto esters with indoles proceeds with high regioselectivities (C3-selective for the indole partner and β′-selective for the β-keto ester) and good yields under mild palladium catalysis at room temperature with a variety of oxidants. Two possible mechanisms involving either late or early involvement of indole are presented.
Palladium-catalyzed domino C-H/N-H functionalization: an efficient approach to nitrogen-bridged heteroacenes.
2015
Palladium-catalyzed domino C-H/N-H functionalization for the synthesis of novel nitrogen-bridged thienoacenes and 10H-benzo[4,5]thieno[3,2-b]indole derivatives from dihaloarene is reported. This domino sequence consists of initial C-H functionalization of the benzo[b]thiophene moiety, followed by Buchwald-Hartwig coupling. This transformation is also useful for the synthesis of highly π-extended compounds.
ChemInform Abstract: Palladium-Catalyzed Dehydrogenative β′-Functionalization of β-Keto Esters with Indoles at Room Temperature.
2012
The dehydrogenative β′-functionalization of α-substituted β-keto esters with indoles proceeds with high regioselectivities (C3-selective for the indole partner and β′-selective for the β-keto ester) and good yields under mild palladium catalysis at room temperature with a variety of oxidants. Two possible mechanisms involving either late or early involvement of indole are presented.
ChemInform Abstract: Palladium-Catalyzed Domino C-H/N-H Functionalization: An Efficient Approach to Nitrogen-Bridged Heteroacenes.
2015
Palladium-catalyzed domino CH/NH functionalization for the synthesis of novel nitrogen-bridged thienoacenes and 10H-benzo[4,5]thieno[3,2-b]indole derivatives from dihaloarene is reported. This domino sequence consists of initial CH functionalization of the benzo[b]thiophene moiety, followed by Buchwald–Hartwig coupling. This transformation is also useful for the synthesis of highly π-extended compounds.