A preliminary study on DNA detection based on relative magnetic permeability measurements and histone HI conjugated superparamagnetic nanoparticles as magnetic tracers

Histone H I conjugated superparamagnetic nanoparticles were assessed for their ability to work as magnetic tracers in conjunction with the relative magnetic permeability metre (MPM-100) for the detection and quantification of DNA (deoxyribonucleic acid). The method employed was based on the electrostatic adsorption of DNA (analyte) to amino group derivatised silica (carrier) and subsequent binding of histone HI conjugated superparamagnetic nanoparticles (magnetic tracer). The sandwich complexes formed were separated from the medium by sedimentation and the relative magnetic permeability of the sediments were measured with the MPM-100. Investigations were made with both calf thymus DNA and plasmid DNA in aqueous buffered solution as well as in a lysed cell culture with high protein content. For the quantification of calf thymus DNA, a linear relationship between the DNA concentration in the sample and the relative magnetic permeability of the pellet was found for DNA concentrations up to 67 mug/ml in buffered solutions as well as in a lysed cell culture. The limits of detection were determined to 12 and 31 mug/ml, respectively. For the quantification of plasmid DNA in buffered solution a linear range was established for concentrations in up to 150 VLg/ml and the limit of detection was determined to 52 mug/lnl. (C) 2003 Elsevier B.V. All rights reserved.