Physisorption of biomolecules to surfaces plays a role in many applications including sensors, bio-adhesion, drug delivery, composites, and coatings. For example, it is known that structural changes of interfacial biomolecules are crucial for properties of sensing surfaces and thus device performance. However, the desired surface properties for optimal change in bio-molecular structure are difficult to predict. Computer simulations can provide detailed information on the interfacial dynamics and aggregation behavior between biomolecules and various surfaces. Using all-atoms MD simulations we investigated the interactions between DNA and silk and various surfaces with different polarity (graphene, graphene oxide 5 % to 60 % oxygen content and SiO<sub>2</sub> surfaces). For DNA, our simulation results showed that graphene denaturates DNA, whereas polar surfaces can retain base pairs and overall structure of DNA. We found that pi-pi stacking is the key interactions for unfolding DNA on graphene but functional groups on polar surface could prevent DNA from forming these interactions. For silk, its secondary structure was lost on both polar and non-polar surfaces but it was observed that graphene oxide with 20 % oxygen content can retain and recover ordered secondary structure better than more polar structure such as SiO<sub>2</sub> surface. Our results also found that combinations of electrostatic interactions, water bridging interactions and hydrogen bonds between silk and surface play a pivotal role in conformational changes and recovery motions of secondary structure of silk on surfaces. Overall, graphene has strong binding with biomolecules due to its propensity to form strong van der Waals interactions such as pi-pi stacking, while polar surface is better for secondary structure retention due to strong electrostatic interactions with biomolecules.

Effect of surface polarity on physisorption of biomolecules: Molecular modeling

251st National Meeting (2016)

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