Single-Molecule Electrical Conductance in Z-form DNA:RNA.

Area of Science:

• Molecular electronics
• Nanotechnology
• Biomolecular science

Background:

• Nucleic acids are promising materials for nanotechnology and biosensing.
• Their electronic properties at the single-molecule level remain largely unexplored.
• The Z-form is an unusual left-handed DNA:RNA conformation potentially involved in gene regulation.

Purpose of the Study:

• To measure and compare the electrical conductance of individual DNA:RNA molecules in A-form and Z-form conformations.
• To understand how molecular structure influences electrical properties.
• To correlate conductance with structural and electronic characteristics.

Main Methods:

• Single-molecule conductance measurements using Scanning Tunneling Microscopy (STM)-assisted break-junction.
• Utilizing the 'blinking' approach for spontaneous junction formation and statistical analysis.
• Circular Dichroism (CD) spectroscopy and ab initio calculations for structural and electronic rationalization.

Main Results:

• Electrical conductivity of the Z-form is one order of magnitude lower than the A-form.
• The Z-form exhibits lower conductivity due to its longer molecular length.
• Higher Highest Occupied Molecular Orbital (HOMO) energy in the Z-form contributes to reduced conductance.

Conclusions:

• The study reveals significant differences in electrical conductivity between A-form and Z-form DNA:RNA molecules.
• Molecular length and HOMO energy are key factors determining single-molecule conductance.
• Findings provide insights into the electronic behavior of exotic nucleic acid structures.