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Professor Jun Fan, Dept Materials Science and Engineering, City University Hong Kong

Event Date: 
Friday, November 23, 2018 - 1:30am to 2:30pm

Modeling Interactions between Hydrophobic Nanosheets and Liposomes

Two-dimensional nanomaterials could cause structural disruption and cytotoxic effects to cells, which greatly challenges their promising biomedical applications including biosensing, bioimaging, and drug delivery. Here, interactions between lipid liposomes and hydrophobic nanosheets is studied utilizing coarse-grained (CG) molecular dynamics (MD) simulations. The simulations reveal a variety of interaction morphologies that depend on the size and the orientation of nanosheets. Dynamic and thermodynamic analyses on the morphology evolution clarify and provide insights into molecule motions such as “nanosheet rotation”, “lipid extraction”, “lipid flip-flop”, and “lipid spreading”. Driven by these molecule motions, hydrophobic nanosheets cause morphology changes of liposomes. The lipid bilayer structure can be corrugated, and the overall liposome sphere can be split or collapsed by large nanosheets. In addition, nanosheets embedded into lipid bilayers greatly weaken the fluidity of lipids, and this effect can be cumulatively enhanced as nanosheets continuously intrude. To further explore the membrane properties affected by the insertion of nanosheet, six different single component lipid membranes are examined. The insertion of nanosheet to the membrane affects the structural and mechanical properties of the bilayers. The bending moduli of the six bilayers all increase. The corresponding molecular mechanism is that the acyl chains of local lipid molecules re-orient and become more ordered after the insertion of the nanosheet. Particularly, the fluid-gel phase transition occurs in the DMPC bilayer. These results could facilitate molecular-level understanding of the cytotoxicity of nanomaterials, provide insight for the design of safer nano-carrier, antibiotics and other bio-nanotechnology applications, and help future nanotoxicology studies associating computational modeling with experiments.

Prof. Jun Fan is an Assistant Professor in the Department of Materials Science and Engineering at the City University of Hong Kong. She received the bachelor’s degree from Tsinghua University, Beijing in 2003, the Master’s degree from McMaster University (Canada) in 2005, and the Ph.D. degree from Princeton University (USA) in 2011. She worked with Prof. Mikko Haataja for her Ph.D. thesis and focused on the structure and dynamics of cell membranes using the phase field method. Afterwards, she moved to the University of Chicago (USA) for as a postdoctoral researcher in Prof. Gregory Voth’s group. She explored the structure, function and mechanical properties of protein complexes, using molecular dynamics simulations and coarse-grained approaches. Her current research interests is to explore molecular mechanisms in nano-bio systems using multi-scale modelling approach as well as fundamental physics for energy storage materials.


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