title: New detection modality for label-free quantification of DNA in biological samples via superparamagnetic bead aggregation.
abstract: Combining DNA and superparamagnetic beads in a rotating magnetic field produces multiparticle aggregates that are visually striking, enabling label-free optical detection and quantification of DNA at levels in the picogram per microliter range. DNA in biological samples can be quantified directly by simple analysis of optical images of microfluidic wells placed on a magnetic stirrer without prior DNA purification. Aggregation results from DNA/bead interactions driven either by the presence of a chaotrope (a nonspecific trigger for aggregation) or by hybridization with oligonucleotides on functionalized beads (sequence-specific). This paper demonstrates quantification of DNA with sensitivity comparable to that of the best currently available fluorometric assays. The robustness and sensitivity of the method enable a wide range of applications, illustrated here by counting eukaryotic cells. Using widely available and inexpensive benchtop hardware, the approach provides a highly accessible low-tech microscale alternative to more expensive DNA detection and cell counting techniques.
authors.affiliation: Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States.
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Leslie
authors.forename: Jingyi
authors.initials: J
authors.lastname: Li
authors.forename: Briony C
authors.initials: BC
authors.lastname: Strachan
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Begley
authors.forename: David
authors.initials: D
authors.lastname: Finkler
authors.forename: Lindsay A L
authors.initials: LA
authors.lastname: Bazydlo
authors.forename: N Scott
authors.initials: NS
authors.lastname: Barker
authors.forename: Doris M
authors.initials: DM
authors.lastname: Haverstick
authors.forename: Marcel
authors.initials: M
authors.lastname: Utz
authors.forename: James P
authors.initials: JP
authors.lastname: Landers
mesh_terms: D004247:DNA / Q000032:analysis / Q000097:blood*; D006801:Humans; D008280:Magnetics / Q000379:methods*; D059346:Magnets / Q000737:chemistry*; D009693:Nucleic Acid Hybridization / Q000379:methods*; D012680:Sensitivity and Specificity
chemical_list: D004247:DNA