New Catalytic DNA Fluorescent and Colorimetric Sensors for On�site and Real�time Monitoring of Industrial and Drinking Water

We have developed new fluorescent and colorimetric sensor technologies for on-site, real-time detection and quantification of toxic metal ions such as lead, mercury and uranium in industrial and drinking waters. We used a combinatorial biology method called in vitro selection to obtain catalytic DNA with high specificity and selectivity for the metal ions. By labeling the DNA with either fluorophore/quencher pairs or gold nanoparticles, we have transformed the catalytic DNA into a highly sensitive and selective fluorescent or colorimetric biosensor, respectively. The presence of metal ions causes the catalytic DNA to cleave, resulting in either a dramatic increase of fluorescent signals or a distinctive change of colors. The sensors are highly sensitive (with detection limit as low as 11 ppt), and selective (with selectivity of over millions fold). The catalytic DNA fluorescent biosensors make it possible to analyze metal ions using simple portable fluorometers, and the catalytic DNA colorimetric biosensors can eliminate equipment altogether. This is possible because the toxic metal ions can be detected through simple color changes, just like pH paper.