title: Asynchronous Magnetic Bead Rotation (AMBR) Microviscometer for Label-Free DNA Analysis.
abstract: We have developed a label-free viscosity-based DNA detection system, using paramagnetic beads as an asynchronous magnetic bead rotation (AMBR) microviscometer. We have demonstrated experimentally that the bead rotation period is linearly proportional to the viscosity of a DNA solution surrounding the paramagnetic bead, as expected theoretically. Simple optical measurement of asynchronous microbead motion determines solution viscosity precisely in microscale volumes, thus allowing an estimate of DNA concentration or average fragment length. The response of the AMBR microviscometer yields reproducible measurement of DNA solutions, enzymatic digestion reactions, and PCR systems at template concentrations across a 5000-fold range. The results demonstrate the feasibility of viscosity-based DNA detection using AMBR in microscale aqueous volumes.
authors.affiliation: Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Yunzi
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: David T
authors.initials: DT
authors.lastname: Burke
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.|Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Raoul
authors.initials: R
authors.lastname: Kopelman
authors.affiliation: Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.|Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Burns
keywords: DNA; genetic analysis; label-free; magnetic; microdevice; paramagnetic; quantitative PCR; restriction digestion; viscometer; viscosity