Hyun Jung Chung, et al., A magneto-DNA nanoparticle system for rapid detection and phenotyping of bacteria, Nature Nanotechnology vol. 8, 2013
A nanoparticle hybridization assay, involving ubiquitous and specific probes that target bacterial 16S rRNAs, was designed to detect amplified target DNAs using a miniaturized NMR device. Ultimately, the magneto-DNA platform will allow both universal and specific detection of various clinically relevant bacterial species, with sensitivity down to single bacteria. Furthermore, the assay is robust and rapid, simultaneously diagnosing a panel of 13 bacterial species in clinical specimens within 2 h.
For bacterial detection, we selected 16S rRNA as the target marker, because a single bacterium contains many 16S rRNA strands (1 x 10³ to 1 x 10⁵ strands). Furthermore, the strands have a high degree of sequence consensus across species (important for general bacterial detection) as well as species-specific variable regions (important for species typing).
There are three steps of signal amplification: (i) PCR amplification of the target nucleic acids; (ii) bead capture and enrichment of target nucleic acids; (ii) magnetic amplification (because a single MNP can affect billions of surrounding water molecules).