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Dual Magnetic-/Temperature-Responsive Nanoparticles for Microfluidic Separations and Assays

Lai, James J. and Hoffman, John M. and Ebara, Mitsuhiro and Hoffman, Allan S. and Estournès, Claude and Wattiaux, Alain and Stayton, Patrick S. Dual Magnetic-/Temperature-Responsive Nanoparticles for Microfluidic Separations and Assays. (2007) Langmuir, 23 (13). 7385-7391. ISSN 0743-7463

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Official URL: http://dx.doi.org/10.1021/la062527g


Astimuli-responsive magnetic nanoparticle system for diagnostic target capture and concentration has been developed for microfluidic lab card settings. Telechelic poly(N-isopropylacrylamide) (PNIPAAm) polymer chains were synthesized with dodecyl tails at one end and a reactive carboxylate at the opposite end by the reversible addition fragmentation transfer technique. These PNIPAAm chains self-associate into nanoscale micelles that were used as dimensional confinements to synthesize the magnetic nanoparticles. The resulting superparamagnetic nanoparticles exhibit a ç-Fe2O3 core (5 nm) with a layer of carboxylate-terminated PNIPAAm chains as a corona on the surface. The carboxylate group was used to functionalize the magnetic nanoparticles with biotin and subsequently with streptavidin. The functionalized magnetic nanoparticles can be reversibly aggregated in solution as the temperature is cycled through the PNIPAAm lower critical solution temperature (LCST). While the magnetophoretic mobility of the individual nanoparticles below the LCST is negligible, the aggregates formed above the LCST are large enough to respond to an applied magnetic field. The magnetic nanoparticles can associate with biotinylated targets as individual particles, and then subsequent application of a combined temperature increase and magnetic field can be used to magnetically separate the aggregated particles onto the poly(ethylene glycol)-modified polydimethylsiloxane channel walls of a microfluidic device. When the magnetic field is turned off and the temperature is reversed, the captured aggregates redisperse into the channel flow stream for further downstream processing. The dual magnetic- and temperatureresponsive nanoparticles can thus be used as soluble reagents to capture diagnostic targets at a controlled time point and channel position. They can then be isolated and released after the nanoparticles have captured target molecules, overcoming the problem of low magnetophoretic mobility of the individual particle while retaining the advantages of a high surface to volume ratio and faster diffusive properties during target capture.

Item Type:Article
Additional Information:Thanks to American Chemical Society editor. The definitive version is available at http://pubs.acs.org The original PDF of the article can be found at Langmuir website : http://pubs.acs.org/journal/langd5
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Other partners > Ecole Nationale Supérieure de Chimie et de Physique de Bordeaux - ENSCPB (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Other partners > University of Washington (USA)
Other partners > Université de Bordeaux 1 (FRANCE)
Laboratory name:
Deposited On:18 Jun 2009 08:29

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