Charge Modulation at Nucleic Acid/MoS₂ Interfaces: Insights from Chronocoulometry for 2D Material-Based Biosensing.

Area of Science:

• Materials Science
• Biotechnology
• Electrochemistry

Background:

• Nucleic acid detection platforms are vital for diagnostics.
• Understanding interfacial charge dynamics is key to improving biosensor specificity.
• Molybdenum disulfide (MoS2) shows promise for biosensing applications.

Purpose of the Study:

• To investigate how interfacial charge (Qsur) at nucleic acid/MoS2 interfaces is modulated by metal ions and nucleic acid properties.
• To elucidate the role of these factors in adsorption-based nucleic acid detection.
• To establish a framework for enhancing the reliability of 2D material-based biosensors.

Main Methods:

• Chronocoulometry was used to measure interfacial charge (Qsur) at nucleic acid/MoS2 interfaces.
• Adsorption of locked nucleic acid and DNA oligomers on MoS2 was studied in the presence of Mg2+ and Na+.
• [Ru-(NH3)6]3+ was employed as an electrostatically adsorbed redox probe.

Main Results:

• Interfacial charge is sensitive to metal ion identity, nucleic acid backbone, strand conformation, and nonspecific adsorption.
• Mg2+ induced stronger electrostatic interactions and charge accumulation than Na+.
• Duplex formation reduced electropositivity, while nonspecific adsorption mimicked hybridization, highlighting the need for blocking layers.

Conclusions:

• Interfacial charge, not steric hindrance, governs redox probe diffusion at nucleic acid/MoS2 interfaces.
• Charge-dependent dynamics are critical for reducing artifacts in biosensors.
• This study provides a framework for developing more specific and reliable 2D material-based nucleic acid biosensors.