On chip sorting of bacterial cells using sugar-encapsulated magnetic nanoparticles

Abstract

Here we describe an integrated microfluidic sorting device, which utilized sugar-encapsulated magnetic nanoparticles to separate a specific strain of bacteria from a mixture solution. In our system, microfluidic devices consisting of two inlets and an electromagnet or a permanent magnet have been constructed by a soft lithography process. The magnetic field generated by either the electromagnet or the permanent magnet was strong enough to attract the bacteria bound to magnetic nanoparticles to cross the stream boundary of the laminar flow. The sorting efficiency was found to depend on both the flow rate and the strength of the magnetic field. The maximum sorting efficiency was measured to be higher than 90% and the selectivity was almost 100%. Since this microfluidic sorting device was able to separate 103 bacterial cells within 1min, it could be used for pathogenic diagnose applications.