Tunable spin-selective transport through DNA with mismatched base pairs

Area of Science:

• Condensed Matter Physics
• Molecular Biophysics
• Nanotechnology

Background:

• Spin-selective transport in DNA is crucial for molecular electronics.
• Homogeneous poly(G)-poly(C) DNA serves as a model system for theoretical studies.
• Understanding the impact of defects, like base pair mismatches, is essential for device reliability.

Purpose of the Study:

• To theoretically investigate the influence of a single mismatched base pair on spin-selective transport in poly(G)-poly(C) DNA.
• To quantify the effect of G-A mispairs on the spin polarization of electrical current.
• To determine the dependence of mispair-induced spin effects on the mismatch location.

Main Methods:

• Theoretical analysis of spin-selective charge transport.
• Modeling of homogeneous poly(G)-poly(C) DNA chains with a single G-A base pair mismatch.
• Calculation of spin polarization of the electrical current as a function of DNA length and mispair position.

Main Results:

• Spin polarization is highly sensitive to the presence of a mispair in DNA shorter than 20 base pairs.
• Replacing a G-C pair with a G-A mispair can decrease, increase (by an order of magnitude), or reverse the spin polarization.
• The location of the G-A mispair within the DNA chain significantly influences the resulting spin-selective current.

Conclusions:

• Single base pair mismatches act as critical modulators of spin-selective transport in short DNA.
• G-A mispairs offer a mechanism to tune spin polarization in DNA-based electronic components.
• Precise control over DNA sequence and defect location is vital for designing spintronic devices.