ja300839n_si_001.pdf (9.58 MB)
New Detection Modality for Label-Free Quantification of DNA in Biological Samples via Superparamagnetic Bead Aggregation
journal contribution
posted on 2015-12-16, 21:12 authored by Daniel
C. Leslie, Jingyi Li, Briony C. Strachan, Matthew R. Begley, David Finkler, Lindsay
A. L. Bazydlo, N. Scott Barker, Doris
M. Haverstick, Marcel Utz, James P. LandersCombining 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.