Ultrasensitive Detection of Metal Ions with DNA Nanostructure

In spite of its greatly scientific and technological importance, developing rapid, low cost and sensitive microarray sensors for onsite monitoring heavy metal contamination remains challenging. Here we develop a DNA nanostructured microarray (DNM) with a tubular three-dimensional sensing surface and an ordered nanotopography for rapid and sensitive multiplex detection of heavy metal ions. In our design, DNA tetrahedral-structured probes (TSPs) are used to engineer the sensing interface with spatially resolved and density-tunable sensing spots, improving the micro-confined molecular recognition. Meanwhile, a bubble-mediated shuttle reaction inside the DNM-functionalized microchannel improves the target-capturing efficiency. Thus, the sensitive and selective detection of multiple heavy metal ions (i.e., Hg²⁺, Ag⁺, and Pb²⁺) with this novel DNM biosensor can be achieved within 5 min. Moreover, the detection limit is down to 10, 10, and 20 nM for Hg²⁺, Ag⁺, and Pb²⁺, respectively. Therefore, the DNM biosensor capable of simultaneously detecting multiple heavy metal ions with sensitivity and selectivity shows great potential to be point-of-test devices.