A portable DNAzyme-based optical biosensor for highly sensitive and selective detection of lead (II) in water sample.

A portable, rapid and cost-effective DNAzyme based sensor for lead ions detection in water samples has been developed using an optical fiber sensor platform. The presence of Pb(2+) cleaves the DNAzymes and releases the fluorescent labeled fragments, which further hybridize with the complementary strands immobilized on the optic fiber sensor surface. Subsequent fluorescent signals of the hybridized fluorescent labeled fragment provides quantitative information on the concentrations of Pb(2+) with a dynamic range from 2-75 nM with a detection limit of 1.03 nM (0.21 ng mL(-1)). The proposed sensor also shows good selectivity against other mono and divalent metal ions and thus holds great potential for the construction of general DNAzyme-based sensing platform for the monitoring of other heavy metal ions. The sensor can be regenerated with a 1% SDS solution (pH 1.9) over 100 times without significant deterioration of the sensor performance. This portable sensor system can be potentially applied for on-site real-time inexpensive and easy-to-use monitoring of Pb(2+) in environmental samples such as wastewater effluents or water bodies.