Sequence dependency of the thermodynamic properties of long DNA double-strands

Abstract

Using the Green's function technique and tight-binding (TB) Hamiltonian method for π-electrons within a ladder model of long DNA double-strands acting as semiconducting nanowires, the temperature and sequence dependency of the Pauli paramagnetic susceptibility (PMS) and electronic heat capacity (EHC) of some selected configurations are investigated. The results show the explicit reliance of the two quantities on the arrangement of the DNA base-pairs (BPs). The notable result of this study is the appearance of three temperature points for which the EHC (PMS) curves of the ordered systems converge (diverge) at the lowest and highest points, while they diverge (converge) at the middle point. Disordered systems exhibit a deviation from the trend of the ordered ones and this is more significant around the higher temperature points. Over a wide range of temperatures, the responses of the poly(GC) and poly(AT) double-helices limit the behavior of the random DNA chains. Our finding could inspire the design of experiments to assess the order of randomness in BP sequencing and also to better set the TB parameters of the model.