COE/Structural Mechanics Seminar
Title: |
Learning From the Bad: Virus-Inspired Design of Nanoparticles for Cell-Type Specific Drug Delivery |
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Speaker: |
Dr. Sulin Zhang |
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Affiliation: |
Department of Engineering Science & Mechanics,Pennsylvania State University |
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When: |
Thursday, April 15, 2010 at 3:00:00 PM |
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Where: |
MRDC Building, Room 4211 |
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Host: |
Ting Zhu | |
Abstract Animal viruses invade their hosts in a rather controlled fashion, a process known as endocytosis. This fascinating adhesion-driven process makes one wonder: what are the parameter space that governs the size selectivity, shape sensitivity, and targeting specificity of endocytosis? In this talk, we use synthetic viruses, i.e., nanoparticles (NPs), to elucidate the governing factors of endocytosis. Through thermodynamic analyses, we reveal that, unlike the adhesion between two inanimate objects where the adhesion strength is commonly regarded as a materials constant, the adhesion strength between an NP and a living cell is a non-local, variable quantity that depends on not only the particle size and the ligand density, but also receptor density that is actively regulated by the cell. The variable adhesion strength leads to a two-dimensional uptake phase diagram in the particle size and ligand density space. We identify from the phase diagram a lower and an upper phase boundary within which the cellular uptake is markedly high and beyond which the cellular uptake vanishes. The lower and upper phase transition boundaries are set, respectively, by the enthalpic and entropic components of the adhesion strength. The design principles of the NPs suggested by the uptake phase diagram are validated by comparisons to the characteristics of viruses and experiments in vitro. Our findings are not only important for understanding the biological behaviors and evolutionary design of cells, but also for engineering NP-based therapeutic and diagnostic agents. As the second part of my talk, I will present a novel and efficient coarse-grained fluid membrane model and its powerful applications. The model features an anisotropic inter-particle pair potential with the interaction strength weighed by the relative particle orientations. Despite its simple mathematical form, the model is highly tunable and faithfully reproduces biologically relevant membrane properties. Both the temporal and spatial scales accessible to our model are at least one order of magnitude higher than those of other existing coarse-grained models. We demonstrate that this new model accurately predict fluid vesicle shape transformation and naturally simulate diffusion-driven domain separation and budding with great ease.. The simple mathematical form along with its comprehensive capabilities endows this model as a model system for 2D fluids. |
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Biography Dr. Sulin Zhang received his PhD from the University of Illinois, Urbana-Champaign in 2002. He then worked as a postdoctoral associate in Northwestern University from 2002-2005 and an Assistant Professor at the University of Arkansas from 2005-2007. He was appointed to the current position as an Assistant Professor of Engineering Science and Mechanics at Penn State University since August, 2007. Dr. Zhang’s research interests generally lie in multiscale modeling of nanostructured and bio-inspired materials, and of processes that occur at nano-bio interfaces. He is particularly interested in the role of Mechanics in Biology. Dr. Zhang is the recipient of The Oak Ridge Ralph E. Powe Junior Faculty Enhancement Award in 2006, and the NSF Career Award in 2007. |
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Notes |
Refreshments will be served. |
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