DNAzyme-based microarray for highly sensitive determination of metal ions

A novel microarray for the multiplex determination of heavy metal ions in aqueous solution based on DNAzymes has been developed with good sensitivity and selectivity. In the present work, metal ion dependent DNAzymes of copper (Cu-Enz) and lead (Pb-Enz) were first associated with their corresponding DNA substrates (Cu-Sub and Pb-Sub) immobilized on the surface of aldehyde-coated slides. After introducing the corresponding metal ions, the DNA cleavage of the substrates caused by the DNAzymes took place, resulting in a dramatic change in fluorescent signal intensity. The proposed microarray method, which can be used as a multi-component assay with high efficiency, combines the high sensitivity and selectivity of DNAzymes with the high throughput and parallel analysis of microarray technology. The method reveals a sensitivity corresponding to 0.6 ppb and 2 ppb for Cu2+ and Pb2+, respectively, which is sufficient to detect them in drinking water. This approach may find potential applications in environmental monitoring, food safety monitoring, clinical toxicology, waste treatment, the cosmetic industry and industrial process monitoring.