Electrochemical Detection of Parts-Per-Billion Lead via an Electrode-Bound DNAzyme Assembly

The development of specific ion sensors is linked to pressing needs for the rapid detection of toxic metals.1-4 Of particular interest has been the detection of lead (Pb2+), an important pollutant with major routes of human exposure arising from lead-based paints and contaminated soils and foodstuffs.5 Because of the often severe effects of lead toxicity, which include renal malfunction and the inhibition of brain development,6 allowable juvenile serum lead levels are just 100 parts-per-billion (ppb).7 Current protocols for the detection of lead require inductively coupled plasma mass spectroscopy (ICP/MS) (see Supporting Information (SI)), a rather complex laboratory technique. Motivated by the desire for rapid, portable means of quantifying low-level lead contamination, recent years have seen the development of fluorescent8 and colorimetric9 sensors achieving parts-per-billion detection limits. These optical methods, however, suffer from