Fluorescent DNA Probing Nanoscale MnO₂: Adsorption, Dissolution by Thiol, and Nanozyme Activity

Area of Science:

• Materials Science
• Biomaterials Science
• Nanotechnology

Background:

• Manganese dioxide (MnO2) possesses beneficial biocompatibility and magnetic properties.
• Understanding DNA-MnO2 interactions is crucial for drug delivery and sensing.
• Limited fundamental knowledge exists regarding DNA adsorption on MnO2.

Purpose of the Study:

• To investigate the adsorption of DNA onto MnO2, considering factors like salt concentration, pH, DNA sequence, and length.
• To compare DNA adsorption on MnO2 with graphene oxide (GO).
• To explore the effect of thiol-containing compounds on MnO2 dissolution and DNA release.
• To develop a DNA-functionalized MnO2 system for glutathione (GSH) detection.
• To examine the influence of DNA on the peroxidase-like activity of MnO2.

Main Methods:

• Utilized carboxyfluorescein (FAM)-labeled DNA oligonucleotides.
• Performed adsorption and desorption studies varying salt concentration, pH, DNA sequence, and length.
• Conducted salt-shock assays to compare DNA affinity on MnO2 versus GO.
• Investigated MnO2 dissolution by thiol-containing compounds.
• Developed and tested a DNA-functionalized MnO2 sensor for GSH detection.
• Assessed the effect of DNA on MnO2's peroxidase-like activity.

Main Results:

• DNA primarily adsorbs to MnO2 via its phosphate backbone, exhibiting stronger affinity than to GO.
• DNA desorbs from MnO2 with inorganic phosphate, while desorption from GO involves adenosine and urea.
• Thiol-containing compounds dissolve MnO2, releasing adsorbed DNA, unlike less soluble metal oxides.
• A DNA-functionalized MnO2 system achieved a detection limit of 383 nM for GSH.
• DNA was observed to inhibit the peroxidase-like activity of MnO2.

Conclusions:

• Established fundamental insights into DNA interactions with MnO2, highlighting backbone adsorption and stronger affinity compared to GO.
• Demonstrated the potential of DNA-functionalized MnO2 for GSH detection.
• Revealed that DNA influences the peroxidase-like activity of MnO2.
• Provided a basis for understanding MnO2 interactions with DNA and thiol-containing biomolecules for potential applications.