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DNAzyme-nanoparticle sensor could be basis of home lead-paint detector.
A sensitive and selective colorimetric sensor for lead may at last provide a simple test for lead in paint. The new type of sensor may also be useful for detecting and measuring other metals, nonmetals, and compounds for applications such as household and environmental monitoring, developmental biology, and clinical toxicology.
Lead in paint is a hazardous neurotoxin, but no simple, inexpensive, and reliable means has been available to test for it. The colorimetric lead-paint test kits available have been found to give "high rates of false-positive and false-negative results." Author believes the sensor can overcome these shortcomings and could lead to "a simple leaded-paint test kit, similar to pH papers." Key to the new sensor are gold nanoparticles and a DNAzyme that catalyzes cleavage of a substrate DNA only when activated by lead. The DNAzyme, DNA substrate, and DNA-functionalized gold nanoparticles combine to form a blue aggregate. In the presence of lead, the substrate is cleaved, aggregate formation is inhibited, and the more highly separated nanoparticles appear red. The intensity of the red color indicates the amount of lead present. Detection ranges can be tuned by adding different amounts of an inactive DNAzyme. And sensors for other analytes can be made with DNAzymes activated by other substances


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