title: Label-free DNA sequencing using Millikan detection.
abstract: A label-free method for DNA sequencing based on the principle of the Millikan oil drop experiment was developed. This sequencing-by-synthesis approach sensed increases in bead charge as nucleotides were added by a polymerase to DNA templates attached to beads. The balance between an electrical force, which was dependent on the number of nucleotide charges on a bead, and opposing hydrodynamic drag and restoring tether forces resulted in a bead velocity that was a function of the number of nucleotides attached to the bead. The velocity of beads tethered via a polymer to a microfluidic channel and subjected to an oscillating electric field was measured using dark-field microscopy and used to determine how many nucleotides were incorporated during each sequencing-by-synthesis cycle. Increases in bead velocity of approximately 1% were reliably detected during DNA polymerization, allowing for sequencing of short DNA templates. The method could lead to a low-cost, high-throughput sequencing platform that could enable routine sequencing in medical applications.
authors.affiliation: Caerus Molecular Diagnostics, Mountain View, CA 94043, USA.
authors.forename: Roger
authors.initials: R
authors.lastname: Dettloff
authors.affiliation: Caerus Molecular Diagnostics, Mountain View, CA 94043, USA.
authors.forename: Danielle
authors.initials: D
authors.lastname: Leiske
authors.affiliation: Promega BioSystems, Sunnyvale, CA 94085, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Chow
authors.affiliation: Caerus Molecular Diagnostics, Mountain View, CA 94043, USA. Electronic address: javier_farinas@caerusmdx.com.
authors.forename: Javier
authors.initials: J
authors.lastname: Farinas
mesh_terms: D059014:High-Throughput Nucleotide Sequencing; D046210:Microfluidic Analytical Techniques; D009821:Oils / Q000737:chemistry*; D010316:Particle Size; D017422:Sequence Analysis, DNA / Q000379:methods*; D013499:Surface Properties
chemical_list: D009821:Oils
keywords: DNA sequencing; Tethered beads