Graphene and graphene oxide (GO), have been used as an active biocompatible surface in various biomedical applications, such as biosensors or drug-delivery. It has been reported that surface oxidations can either enhance or deteriorate the bio-compatibility, functionality, and stability of biomolecules on the surfaces. However, fundamental understanding of how surface properties influences biomolecular structure and properties remains to be elucidated. We performed atomistic molecular dynamics simulations in order to find (1) the relationship between biomolecules’ structural stability and surface polarity and (2) key interactions that govern the physisorption process. In this study, two types of biomolecules, DNA and silk fibroin protein, were examined. For DNA, simulation results discovered three important regimes that depend on the surface oxidation rate: on pristine graphene or GO with low oxidation rate (GO 0% - 5 %), DNA lost its structural stability due to strong van der Waals (VDW)-driven interactions, such as <i>pi-pi </i>stacking; on GO with moderate oxidation rate (GO 10% - 25%), DNA maintained its folded structures due to balanced VDW and electrostatic contributions; however, on GO with high oxidation rate (GO 30% - 60%), strong electrostatic driven interactions, such as interfacial hydrogen bonds induced a loss of internal interactions of DNA. For silk protein, we found that the GO 20% surface with the balanced interfacial interactions between VDW and electrostatic can not only preserve secondary structures of the silk protein but also restore the ordered structures from disordered chains. In contrast, this structure can be disrupted on pristine graphene due to strong VDW-driven interactions. Overall, our computational results not only revealed the underlying process of physisorption between bio-molecules and graphene-based surfaces but also provided insights in designing many applications of biofunctionalized surfaces.

Role of graphene oxidation on physisorption of biomolecules using computational modeling

254th National Meeting (2017)

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