Chapter 8. New Trends in DNA Sensors for Environmental Applications: Nanomaterials, Miniaturization, and Lab-on-a-Chip Technology

DNA as Sensors and Imaging Agents for Metal Ions

“…In this way, DNAzymes that are dependent on Mg 2+ , , Zn 2+ , , Pb 2+ , , Cu 2+ , , UO 2 2+ , Hg 2+ , Co 2+ , and Mn 2+ for various chemical and biological reactions have been successfully discovered. Among them, DNAzymes that can cleave or ligate nucleic acids have been widely applied in the development of selective and sensitive sensors for different metal ions, after they are conjugated with suitable signal reporters (Figure ). ,,− …”

“…In contrast, because it is relatively easy to modify DNA with a reporter group, the reporter can be placed further away from the binding site and signal transduction can be realized based on the melting temperature differences before and after metal binding. Therefore, the third advantage of DNA-based sensors is the straightforward nature of transforming metal-ion recognition into different signal outputs and achieving efficient signal amplification for more sensitive detection without sacrificing metal-ion selectivity. ,− ,− ,,,− As shown in Figure , through the introduction of fluorophores, chromophores, nanomaterials, electrochemical tags, and Raman tags into the same design strategy, DNA-based sensors for metal ions based on fluorescence, colorimetry, electrochemistry, and surface Raman enhancement have been developed. In addition, many DNA-related enzymatic reactions and DNA-functionalized nanomaterials have been successfully incorporated into DNA-based sensors for signal amplification to achieve more sensitive detection of metal ions.…”

“…To meet the challenge, two approaches have been established to identify metal-ion-selective DNA sequences. The first is through a combinatorial technique called in vitro selection, where random DNA libraries containing diverse DNA sequences are used to obtain desired sequences that can bind specific metal ions or use them as cofactors for catalysis. − The second approach utilizes DNA sequences discovered to be able to bind specific metal ions based on the study of the DNA structures or rational design. − By incorporation of signal reporters such as chromophores, fluorophores, electrochemical tags, and Raman tags, these metal-ion-specific DNA sequences found by these two approaches have been transformed into colorimetric, fluorescent, electrochemical, and Raman sensors and imaging agents for a broad range of metal ions with high sensitivity and selectivity. ,,− This review covers the recent advances in this area (Table ), with more focus on DNAzymes as sensors for metal ions.…”