Sequence-Specific DNA Detection at 10 fM by ElectromechanicalSignal Transduction

摘要

Target DNA fragments at 10 fM concentration (approximately 6 × 10⁵ molecules) were detected against a DNA background simulating the noncomplementary genomic DNA present in real samples using a simple, PCR-free, optics-free approach based on electromechanical signal transduction. The development of a rapid, sensitive, and cost-effective nucleic acid detection platform is highly desired for a range of diverse applications. We previously described a potentially low-cost device for sequence-specific nucleic acid detection based on conductance change measurement of a pore blocked by electrophoretically mobilized bead-(peptide nucleic acid probe) conjugates upon hybridization with target nucleic acid. Here, we demonstrate the operation of our device with longer DNA targets, and we describe the resulting improvement in the limit of detection (LOD). We investigated the detection of DNA oligomers of 110, 235, 419, and 1613 nucleotides at 1 pM to 1 fM and found that the LOD decreased as DNA length increased, with 419 and 1613 nucleotide oligomers detectable down to 10 fM. In addition, no false positive responses were obtainedwith noncomplementary, control DNA fragments of similar length. The1613-base DNA oligomer is similar in size to 16S rRNA, which suggeststhat our device may be useful for detection of pathogenic bacteriaat clinically relevant concentrations based on recognition of species-specific16S rRNA sequences.