Metal ion detection using functional nucleic acids and nanomaterials

- The development of biosensors for metal ion detections that employ both functional nucleic acids (FNAs) and nanomaterials is intensively reviewed.
- FNAs mainly include DNAzymes, G-quadruplexes, and mismatched base pairs and advanced nanomaterials cover gold nanoparticles, quantum dots, carbon nanotubes, and graphene oxide.
- The recognition principles and signal conversion mechanisms of FNAs and nanomaterials are introduced.
- The challenges and future directions of metal ion sensors are also discussed.

Metal ion detection is critical in a variety of areas. The past decade has witnessed great progress in the development of metal ion sensors using functional nucleic acids (FNAs) and nanomaterials. The former has good recognition selectivity toward metal ions and the latter possesses unique properties for enhancing the performance of metal ion sensors. This review offers a summary of FNA- and nanomaterial-based metal ion detection methods. FNAs mainly include DNAzymes, G-quadruplexes, and mismatched base pairs and nanomaterials cover gold nanoparticles (GNPs), quantum dots (QDs), carbon nanotubes (CNTs), and graphene oxide (GO). The roles of FNAs and nanomaterials are introduced first. Then, various methods based on the combination of different FNAs and nanomaterials are discussed. Finally, the challenges and future directions of metal ion sensors are presented.