Sensing Parts-per-Trillion Cd2+, Hg2+ and Pb2+ Collectively and Individually Using Phosphorothioate DNAzymes
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Cadmium, mercury, and lead are collectively banned by many countries and regions in electronic devices due to their extremely high toxicity. To date, no sensing method can detect them as a group and also individually with sufficient sensitivity and selectivity. An RNA-cleaving DNAzyme (Ce13d) was recently reported to be active with trivalent lanthanides, which are hard Lewis acids. In this work, phosphorothioate (PS) modifications were systematically made on Ce13d. A single PS modification at the substrate cleavage site shifts the activity from being dependent on lanthanides to soft thiophilic metals. By incorporating the PS modification to another DNAzyme, a sensor array was prepared to detect each metal. Individual sensors have excellent sensitivity (limit of detection = 4.8 nM Cd2+, 2.0 nM Hg2+, and 0.1 nM Pb2+). This study provides a new route to obtain metal-specific DNAzymes by atomic replacement and also offers important mechanistic insights into metal binding and DNAzyme catalysis.
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Po-Jung Jimmy Huang, Juewen Liu (2014). Sensing Parts-per-Trillion Cd2+, Hg2+ and Pb2+ Collectively and Individually Using Phosphorothioate DNAzymes. UWSpace. http://hdl.handle.net/10012/11367