(593i) Molecular Dynamics Simulations of Nanostructures Formed By Hydrophobins and Oil in Seawater | AIChE

(593i) Molecular Dynamics Simulations of Nanostructures Formed By Hydrophobins and Oil in Seawater

Authors 

Hung, F. - Presenter, Northeastern University
Vodopivec, A., Northeastern University
Chen, Y., Louisiana State University
Russo, P., Georgia Institute of Technology
Classical molecular dynamics simulations using the Martini coarse-grained force field were performed to study oil nanodroplets surrounded by fungal hydrophobin (HP) proteins in seawater. The class I EAS and the class II HFBII HPs were studied along with two model oils, benzene and n-decane. Both HPs exhibit free energy minima at the oil-seawater interface, which are much deeper in benzene systems than in interfaces with n-decane. Smaller surface tensions are observed at benzene-seawater interfaces coated with HPs compared to their n-decane counterparts, in which the surface tension remains unchanged upon increases in the surface concentration of HPs, which in contrast lead to surface tension reductions at the benzene-seawater interface. EAS has a larger tendency to cluster together in the interface compared to HFBII, with both HPs having larger coordination numbers when surrounding benzene droplets compared to when they are around n-decane nanoblobs. The HP/oil nanostructures in seawater examined have radii of gyration ranging between 2-12 nm, where the n-decane structures are larger and have more irregular shapes (as quantified through different shape measures) compared to the benzene blobs. The n-decane molecules within the nanostructures form a compact spherical core, with the HPs partially covering its surface and clustering together, conferring irregular shapes to the nanostructures. The EAS/n-decane structures are larger and have more irregular shapes compared to their HFBII/n-decane counterparts. In contrast, in the HP/benzene structures both HPs tend to penetrate into the benzene part of the droplet. The HFBII/benzene structures having the larger benzene/HP ratios examined tend to be more compact and spherical compared to their EAS/benzene counterparts; however, some of the HFBII/benzene systems that have smaller benzene/HP ratios have a more elongated structure compared to their EAS counterparts. This simulation study provides insights into HP/oil nanostructures that are smaller than the oil droplets and gas bubbles recently studied in experiments, and thus might be challenging to examine with experimental techniques.