Preferential Adsorption of Single-Stranded DNA on Graphene Oxide with Hydroxyl and Epoxy Groups

The interaction between DNA and two-dimensional materials, such as graphene oxide (GO), has aroused significant research interest due to its potential applications, including biosensors, drug delivery, and gene therapy. However, the difference in interaction between DNA and oxygen functional groups on GO remains unclear, and direct observation at the experimental level is still challenging. In this work, we investigated the adsorption process of a single-stranded DNA (ssDNA) onto GO exhibiting a series of oxidation degrees by molecular dynamics simulations. We found that the ssDNA preferentially binds to hydroxyl groups (-OH) over epoxy groups (-O-) on the GO surface. This preferential adsorption feature may be attributed to the stronger tendency of ssDNA to form hydrogen bonds (HBs) with hydroxyl groups compared to epoxy groups in aqueous solutions. Further analysis indicates that the affinity interaction between ssDNA and hydroxyl groups presumably increases the oxidation degree of GO, thus suggesting a better binding between ssDNA and GO. This work is not only expected to provide the underlying mechanism of ssDNA onto graphene-based interfaces but also offers a deeper understanding of the structures of DNA-two-dimensional complexes, which may potentially contribute to designing new molecular structures for bio-sensing-related nano-devices and nanostructures.