Unexpected sequence adsorption features of polynucleotide ssDNA on graphene oxide†
The sequence features of single-stranded DNA (ssDNA) adsorbed on a graphene oxide (GO) surface are important for applications of the DNA/GO functional structure in biosensors, biomedicine, and materials science. In this study, molecular dynamics (MD) simulations were used to examine the adsorption of polynucleotide ssDNAs (A12, C12, G12, and T12) and single nucleotides (A, C, G, and T) on the GO surface. For the latter case, the nucleotide–GO interaction energy followed the trend G > A > C > T, even though it was influenced by specific adsorption sites. In the case of polynucleotides, unexpectedly polythymidine (T12) had the strongest interaction with the GO surface. The angle distributions of the adsorbed nucleobases indicated that T12 was more likely to form a quasi-parallel structure with GO compared to A12, C12, or G12. This was attributed to the weakest π-stacking interactions of thymine. Weaker intra-molecular base-stacking interactions made it easier to break the structures of pyrimidine bases relative to those of purine bases. Weaker inter-molecular base-stacking interactions between T12 and the GO surface enabled T12 to adjust its structure easily to a more stable one by slipping on the surface. This result provides a new understanding of polynucleotide ssDNA adsorption on GO surfaces, which will help in the design of functional DNA/GO structure-based platforms.