Density-Based Diamagnetic Separation: Devices for Detecting Binding Events and for Collecting Unlabeled Diamagnetic Particles in Paramagnetic Solutions

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• 作者：Adam Winkleman ; Raquel Perez-Castillejos ; Katherine L. Gudiksen ; Scott T. Phillips ; Mara Prentiss ; George M. Whitesides
• 刊名：Analytical Chemistry
• 出版年：2007
• 出版时间：September 1, 2007
• 年：2007
• 卷：79
• 期：17
• 页码：6542 - 6550
• 全文大小：770K
• 年卷期：v.79,no.17(September 1, 2007)
• ISSN：1520-6882

文摘

This paper describes the fabrication of a fluidic device fordetecting and separating diamagnetic materials that differin density. The basis for the separation is the balance ofthe magnetic and gravitational forces on diamagneticmaterials suspended in a paramagnetic medium. Thepaper demonstrates two applications of separations involving particles suspended in static fluids for detectingthe following: (i) the binding of streptavidin to solid-supported biotin and (ii) the binding of citrate-capped goldnanoparticles to amine-modified polystyrene spheres. Thepaper also demonstrates a microfluidic device in whichpolystyrene particles that differ in their content of CH₂Clgroups are continuously separated and collected in aflowing stream of an aqueous solution of GdCl₃. Theprocedures for separation and detection described in thispaper require only gadolinium salts, two NdFeB magnets,and simple microfluidic devices fabricated from poly(dimethylsiloxane). This device requires no power, hasno moving parts, and may be suitable for use in resource-poor environments.