Nonlinear mechanical response of finite-length soft composites with random dislocations

Area of Science:

• Biophysics
• Materials Science
• Computational Biology

Background:

• Vibrational properties of nucleic acids are crucial for their function.
• Understanding the impact of structural defects like dislocations is essential.
• Existing models often simplify the inherent randomness in RNA and DNA structures.

Purpose of the Study:

• To investigate the effects of random dislocations on the vibrational properties of finite-length RNA and DNA.
• To model nucleic acid structures with realistic randomness using Hooke's law and varying spring stiffness.
• To analyze the mechanical response of these structures to dislocations.

Main Methods:

• Utilized a harmonic Hamiltonian and Green's function method.
• Modeled RNA with a half ladder model and DNA with fishbone and strand models.
• Simulated random dislocations by displacing mass-spring ensembles.

Main Results:

• Increased model length suppresses dislocation influence on vibration spectra for both RNA and DNA.
• Dislocation effects are more pronounced at low frequencies.
• Dislocations introduce new vibrational states in density of states (DOS) curves and cause nonlinear responses.

Conclusions:

• The methodology provides insights into the mechanical response of damaged RNA and DNA.
• Structural randomness and dislocations significantly alter vibrational spectra.
• The findings highlight the complex, nonlinear mechanical behavior of nucleic acids under duress.