DNAzyme-Based Sensing for Metal Ions in Ocean Platform

The ocean contains a number of metal ions that are either beneficial or detrimental to marine lives or ecology. Developing sensors for on-site and real-time detection of these metal ions plays an important role in our understanding the ocean as well as its protection. DNAzymes, DNA molecules with enzymatic functions, have emerged as a new class of sensing molecules for metal ions, because DNAzymes with high affinity and specificity for almost any metal ions at a specific oxidation state can be obtained through in vitro selection. By integrating the DNAzyme with different signal transduction molecules, such as fluorophores or nanoparticles, DNAzyme-based sensors for a broad range of metal ions with high sensitivity (with limit of detection down to ppt) and selectivity (with over a million fold) have been reported. In this chapter, we summarize recent progress in DNAzyme-based sensors for metal ions and describe detailed protocols in designing fluorescent and colorimetric sensors for uranium and mercury. The diverse range of metal ions it can detect as well as its excellent sensing properties makes DNAzyme an excellent choice for ocean sensing.