Since magnetic nanomaterials conjugating with biomolecules have been widely applied in biochemical separation, targeted drug delivery, immunoassay, biosensor, and other fields, there is an increased need for controlled transport of their small volumes of liquids. With the joint support of National Nature Science Foundation of China and the innovation foundation of the Chinese Academic Sciences, a research team led by Prof. Lei Jiang from Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences has recently developed a simple, high-efficiency and flexible method to reversibly oriented transport superparamagnetic microlitre-sized liquid droplets between superhydrophobic solid surfaces with no lost volume using alternating magnetic fields, which has been published in J. Am. Chem. Soc. 2007, 129, 1478-1479.

According to their previous work, researchers found that aligned polystyrene (PS) nanotube layer showed strong adhesive effect to a water microdroplet, and therefore could be used as a “mechanical hand” to transfer small water droplets from a superhydrophobic surface to a hydrophilic one without any loss or contamination (Adv. Mater. 2005, 17, 1977). Based on this study, they further expanded its application in intelligently no lost transport of superparamagnetic microdroplet by utilizing the sensitive responsive property of superparamagnetic microdroplet to applied magnetic fields. It is greatly important for many localized chemical or biological reactions, traced analysis, in situ detection, and is expect to open up new perspective for applications in physics, chemistry, biology, pharmaceutical and microfluidics.

J. Am. Chem. Soc.（2007, Vol. 129, 1478-1479）

Figure No lost transport processes of a superparamagnetic microdroplet in alternating magnetic fields.