(681c) Nanoparticle-Based, PCR-Less Detection and Isolation of Molecular Biomarkers

The molecular detection of biomarkers that are physiologically present at very low concentration is important not only for diagnostics, but also for monitoring disease progression and efficacy of therapy. The ability of small capture probes to interact with individual molecules has lead to ultrasensitive nanotechnology-based detection assays; however, these assays are unable to also isolate the molecules of interest for further analysis. Here we present an ultrasensitive, small volume, PCR-less assay for the detection and simultaneous isolation of soluble biomolecules (proteins, ssDNA/RNA) or surface expressed proteins. This assay consists of magnetic-fluorescent nanoparticles (i.e., MagDots) conjugated to molecules of interest, which are then manipulated by mobile magnetic traps on a magnetic microarray using external electromagnets. Using this assay, we have isolated leukocytes based on CD45 receptor expression, with in situ receptor quantification using quantum dot fluorescence. We have also detected and isolated avidin and short p53 ssDNA from 10^-10 M solutions in a 5 µl sample volume. A maximum sensitivity of the system of 10^-16 M has been demonstrated. Additionally simultaneous detection of protein and DNA targets has also been demonstrated. This technology will eventually be combined with a lab-on-chip platform incorporating mixing, detection, quantification and isolation of biomarkers. This technology has potential applications in diagnostics, nanoscale synthesis, and chromatography.