Rapid, cost-effective DNA quantification via a visually-detectable aggregation of superparamagnetic silica-magnetite nanoparticles

The mechanism of the DNA quantitation assay, nanoscale SiO2-coated Fe3O4 (Fe3O4@SiO2) particles, are synthesized via a solvothermal method.

Nano Research May 2014, Volume 7, Issue 5, pp 755-764     Qian Liu(1)(4); Jingyi Li(1)(4); Hongxue Liu(5); Ibrahim Tora(1); Matthew S. Ide(6); Jiwei Lu(5); Robert J. Davis(6); David L. Green(6); James P. Landers (1)(2)(3)(4)  

1. Department of Chemistry, University of Virginia, McCormick Road, P. O. Box 400319, Charlottesville, Virginia, 22904, USA

 2. Department of Pathology, University of Virginia Health Science Center, Charlottesville, Virginia, 22908, USA

3. Department of Mechanical Engineering, University of Virginia, Charlottesville, Virginia, 22904, USA 4. Center for Microsystems for the Life Sciences, University of Virginia, Charlottesville, Virginia, 22904, USA

5. Department of Materials Science & Engineering, University of Virginia, P. O. Box 400745, 395 McCormick Road, Charlottesville, Virginia, 22904-4745, USA 6. Department of Chemical Engineering, University of Virginia, 123 Engineers’ Way, Charlottesville, Virginia, 22904, USA    


 DNA and silica-coated magnetic particles entangle and form visible aggregates under chaotropic conditions with a rotating magnetic field, in a manner that enables quantification of DNA by image analysis. As a means of exploring the mechanism of this DNA quantitation assay, nanoscale SiO2-coated Fe3O4 (Fe3O4@SiO2) particles are synthesized via a solvothermal method. Characterization of the particles defines them to be ∼200 nm in diameter with a large surface area (141.89 m2/g), possessing superparamagnetic properties and exhibiting high saturation magnetization (38 emu/g). The synthesized Fe3O4@SiO2 nanoparticles are exploited in the DNA quantification assay and, as predicted, the nanoparticles provide better sensitivity than commercial microscale Dynabeads® for quantifying DNA, with a detection limit of 4 kilobase-pair fragments of human DNA. Their utility is proven using nanoparticle DNA quantification to guide efficient polymerase chain reaction (PCR) amplification of short tandem repeat loci for human identification.