Dendritic coupling agents and superparamagnetic nanoparticles (MNPs)

Recycling of metallodendritic catalysts

MNPs (superparamagnetic nanoparticles) usually called ferrofluids have been widely used for few decades in the field of biotechnology, for biomedical applications, such as magnetic carriers for bioseparation, enzyme and proteins immobilization, and contrast enhancing media. Recently, an attractive application was found in the field of catalysis. Indeed, MNPs may be used as inorganic supports of homogeneous catalysts. These kind of new catalysts may be recovered by magnetization with a simple external magnet (see picture below). We have developed the grafting of catalysts onto MNPs. This can be achieved by immobilization of homogeneous catalysts onto core-shell gamma-Fe2O3 MNPs based on an oxide/polymer or an oxide/silica structure. These nanoparticles consist of a magnetic iron oxide core coated by a cross-linked polymer or a silica shell. Recently, the ability of dendronized molecules to increase the surface functionalization of MNPs by fluorescent dendrons grafted onto gamma-Fe2O3/polymer MNPs was examined. The presence of chelating diphosphines on the dendron part is a key condition for the stability and the efficiency of this supported catalyst in Suzuki C–C cross-coupling reactions with a broad range of halogenoarenes. The recovery and the re-use of the catalyst were easily achieved at least 25 times without any significant loss of activity.

JPEG - 12.2 ko

Partners : ISM, Univ. Bordeaux/ADEMTECH S.A. /CRPP, Univ. Bordeaux/ ENITAB-CBMN, Univ. Bordeaux/Univ. Alcalá (Spain).

Recent publications :

Rosario-Amorin D., Gaboyard M., Clérac R., Nlate S., Heuzé K. Enhanced catalyst recovery in aqueous copper free Sonogashira cross-coupling reaction Dalton Trans., 2011, 40, 44-46

Rosario-Amorin D., Wang X., Gaboyard M., Clérac R., Nlate S., Heuzé K. Dendron-functionalized core-shell superparamagnetic nanoparticles : magnetically recoverable and reusable catalysts for Suzuki C-C cross-coupling reactions Chem. Eur. J., 2009, 15, 12636-12643 (article selected by Synfacts, Highlights in Current Synthetic Organic Chemistry, 2010, 3, 367).

Heuzé K., Rosario-Amorin D., Nlate S., Gaboyard M., Bouter A., Clerac R. Efficient strategy to increase the surface functionalization of core-shell superparamagnetic nanoparticles using dendron grafting New J. Chem., 2008, 32, 383-387.

Synthesis of nanofilms with dendritic grafts for biomolecules immobilization

During the last decades, there was a real demand to develop new methods for biological species analysis. In this field, biosensors provide a fast time analysis in complex medium, and it has a strong potential for the development of new analytical tools in the field of biotechnology. However, the efficiency of biosensors depends on the specific chemistry at the interface between solid supports and biological species to be detected, such as proteins. In this work, we are focalizing on the development of new dendritic molecules for surface chemical modification. Indeed, the synthesis of dendritic organosiloxanes RSiX3 (X=Cl or OCH3 or OEt3) is envisaged for their immobilization on silica surfaces or core-shell superparamagnetic nanoparticles (gamma-Fe2O3/SiO2) MNPs via the formation of covalent bonds Si-O-Si with silanol groups at the silica surfaces. We are developing well-organized and densed monolayers on SiO2 surfaces or onto core-shell MNPs for large implications in the field of environment or health via the design of biosensors, or for proteomic techniques. The dendritic structures of the coupling agents will induce a larger flexibility as well as a larger number of potential sites for biomolecules immobilization.

JPEG - 17 ko

Monolayer of organosilanes on SiO2 surface (left) and silica core-shell gamma-Fe2O3 MNPs (right).

JPEG - 6.3 ko

Partners : ISM, Univ. Bordeaux/ADEMTECH S.A.