Magnetic actuator for the control and mixing of magnetic bead-based reactions on-chip
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While magnetic bead (MB)-based bioassays have been implemented in integrated devices, their handling on-chip is normally either not optimal—i.e. only trapping is achieved, with aggregation of the beads—or requires complex actuator systems. Herein, we describe a simple and low-cost magnetic actuator to trap and move MBs within a microfluidic chamber in order to enhance the mixing of a MB-based reaction. The magnetic actuator consists of a CD-shaped plastic unit with an arrangement of embedded magnets which, when rotating, generate the mixing. The magnetic actuator has been used to enhance the amplification reaction of an enzyme-linked fluorescence immunoassay to detect Escherichia coli O157:H7 whole cells, an enterohemorrhagic strain, which have caused several outbreaks in food and water samples. A 2.7-fold sensitivity enhancement was attained with a detection limit of 603 colony-forming units (CFU) /mL, when employing the magnetic actuator.
KeywordsMagnetic beads Magnetic actuator Lab on a chip Magnetic mixing Immunoassay
The authors gratefully acknowledge the financial support of the Ministerio de Economía y Competitividad and FEDER (project CTQ2012-36165) and the Government of Catalonia (SGR 2009–0323 and scholarship FI-DGR 2012, co-funded by the ESF). The authors thank D. Izquierdo and I. Garcés for the development of the optical detection system, Prof. J. Mas for the use of the microbiology facilities, and N. Vigués, F. Pujol and N. Tomás for helpful discussion and technical advice.
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