Charge transport in individual short base stacked single-stranded RNA molecules

Area of Science:

• Biophysics
• Molecular Biology
• Nanotechnology

Background:

• Charge transport in biomolecules is vital for biological functions and technological applications like biosensors.
• Understanding the charge transport properties of RNA is crucial due to its biomedical significance, but remains poorly understood.

Purpose of the Study:

• To measure and understand the electrical conductance of single-stranded RNA (ssRNA) sequences.
• To investigate the structural and electronic factors influencing charge transport (CT) in RNA compared to DNA.

Main Methods:

• Utilized Scanning Tunneling Microscopy-assisted molecular break junction method to determine single-molecule conductance.
• Employed Circular Dichroism (CD) spectroscopy and Molecular Dynamics (MD) simulations to analyze molecular conformations.
• Applied computational molecular modeling and Machine Learning for data interpretation.

Main Results:

• ssRNA sequences with base-stacking capability showed measurable single-molecule conductance (around 10^-6 S).
• Equivalent length single-stranded DNA (ssDNA) sequences exhibited featureless conductance histograms.
• Extended ssRNA conformations with base-stacking were identified, contrasting with folded ssDNA conformations.

Conclusions:

• Measurable charge transport in RNA is linked to extended, base-stacking stabilized conformations with delocalized HOMO energy levels.
• Efficient charge transport in RNA is facilitated by base-stacking pathways, unlike DNA's tendency to form closed structures.