Gauging the Nanotoxicity of h2D-C2N toward Single-Stranded DNA: An in Silico Molecular Simulation Approach.

Recent toxicological assessments of graphene, graphene oxides, and some other two-dimensional (2D) materials have shown them to be substantially toxic at the nanoscale, where they inhibit and eventually disrupt biological processes. These shortfalls of graphene and analogs have resulted in a quest for novel biocompatible 2D materials with minimum cytotoxicity. In this article, we demonstrate C2N (h2D-C2N), a newly synthesized 2D porous graphene analog, to be non-nanotoxic toward genetic materials from an "in-silico" point of view through sequence-dependent binding of different polynucleotide single-stranded DNA (ssDNA) onto it. The calculated binding energy of nucleobases and the free energy of binding of polynucleotides follow the common trait, cytosine > guanine > adenine > thymine, and are well within the limits of physisorption. Ab-initio simulations completely exclude the possibility of any chemical reaction, demonstrating purely noncovalent binding of nucleobases with C2N through a crucial interplay between hydrogen bonding and π-stacking interactions with the surface. Further, we show that the extent of distortion inflicted upon ssDNA by C2N is negligible. Analysis of the density of states of the nucleobase-C2N hybrids confirms minimum electronic perturbation of the bases after adsorption. Most importantly, we demonstrate the potency of C2N in nucleic acid transportation via reversible binding of ssDNA. The plausible use of C2N as a template for DNA repair is illustrated through an example of C2N-assisted complementary ssDNA winding.