Fluorescent DNA Probing Nanoscale MnOsub2/sub: Adsorption, Dissolution by Thiol, and Nanozyme Activity

摘要

Manganese dioxide (MnO_(2)) is an interesting material due to its excellent biocompatibility and magnetic properties. Adsorption of DNA to MnO_(2) is potentially of interest for drug delivery and sensing applications. However, little fundamental understanding is known about their interactions. In this work, carboxyfluorescein (FAM)-labeled DNA oligonucleotides were used to explore the effect of salt concentration, pH, and DNA sequence and length for adsorption by MnO_(2), and comparisons were made with graphene oxide (GO). The DNA desorbs from MnO_(2) by free inorganic phosphate, while it desorbs from GO by adenosine and urea. Therefore, DNA is mainly adsorbed on MnO_(2) through its phosphate backbone, and DNA has a stronger affinity on MnO_(2) than on GO based on a salt-shock assay. At the same time, DNA was used to study the effect of thiol containing compounds on the dissolution of MnO_(2). Adsorbed DNA was released from MnO_(2) after its dissolution by thiol, but not from other metal oxides with lower solubility such as CeO_(2), TiO_(2), and Fe_(3)O_(4). DNA-functionalized MnO_(2) was then used for detecting glutathione (GSH) with a detection limit of 383 nM. Finally, DNA was found to inhibit the peroxidase-like activity of MnO_(2). This study has offered many fundamental insights into the interaction between MnO_(2) and two important biomolecules: DNA and thiol-containing compounds.