Charge Transport Properties of Biomolecules*

Double-stranded DNA (dsDNA) and dsRNA hold great promises in molecular electronics. We characterize the charge transport properties of dsRNA for different sequences and compare them with similar sequences of dsDNA in two extreme charge transport regimes – incoherent charge hopping regime and coherent electron transport regime. We find that the relative conductance of A-form dsRNA and B-form dsDNA depends on the mechanism of charge transport. This is attributed to various structural differences in dsDNA and dsRNA. We also study the effect of stretching and propose a method to detect conformational changes using electrical measurements. Despite the twist-stretch coupling of dsRNA and dsDNA being different under external force, dsRNA shows similar structural polymorphism to dsDNA under different pulling protocols. Our atomistic MD simulations show that overstretching dsRNA along the 3’ ends (OS3) leads to the emergence of S-RNA whereas overstretching along the 5’ ends (OS5) leads to melting of dsRNA. Using the dsRNA morphology from pulling MD simulations, we use a multiscale method involving ab initio DFT calculations and Kinetic Monte Carlo (KMC) simulations to estimate the conductance of dsRNA and find that the conformational changes drastically affect its conductance.