Victoria Sun

Contact:

Victoria Sun

Mork Family Department of Chemical Engineering and Materials
Science

3651 Watt Way
VHE 710
Los Angeles, CA 90089-1211
Email: victoria.sun@usc.edu

Biomimetic Membranes

Passive transport through the cell membrane is a process by which drugs and environmental toxins can enter biological systems. A model often used to describe this process is Overton’s rule, which broadly states that the efficacy of a drug is proportional to its lipid solubility.1 Recent studies however, have shown transport of some polar molecules across the bilayer to be in direct violation of Overton’s rule.2 An improved understanding of the mechanism by which this process occurs, and the potential to address such inconsistencies, is a direct motivation for the present work.

My research aims to develop a novel optical detection instrument, which enables simultaneous imaging of the x-y-z position of a single molecule within a lipid bilayer. Previous work in the Armani group (2010) have demonstrated the feasibility of forming lipid bilayers on the surface of optical microcavities, exciting fluorophores within the lipid bilayer, and simultaneously monitoring the resonant frequency while imaging the cavity surface.3 The non-linear decay of the optical field from the cavity surface allows us to track the motion of molecules through the membrane at high resolution, providing an improved understanding of diffusing molecules.

Polymeric Thin Film Coatings

Polymeric thin film coatings are used in numerous industrial applications, such as sealants and strengthening agents. As the applications for polymer and nanocomposite coatings increase, the ability to characterize the mechanical and optical properties of polymer thin films at the nanoscale level is critical. By developing a predictive model for such properties as changes in temperature occur, scientists will have a better understanding of a material’s behavior, and thus be able to optimize its properties for various applications.

A new optical sensor was recently (2012) developed in the Armani Group which demonstrates a method to detect temperature-induced changes in the refractive index of polymer thin films. Because the temporal resolution of this method is sub-millisecond, investigations into how films are reacting to environmental changes can be made in real-time.


References

1. Grime JMA, Edwards MA, Rudd NC, Unwin PR (2008) Quantitative visualization of passive transport across bilayer lipid membranes. Proc Natl A6ad Sci USA 105:14277–14282. 2. Barry PH, Diamond JM (1984) Effects of unstirred layers on membrane phenomena. Physiol Rev 64:763–872. 3. Freeman LM, Li S, Dayani Y, Choi H, Malmstadt N, Armani AM (2011) Excitation of Cy5 in self-assembled lipid bilayers using optical microresonators. Applied Physics Letters 98:143703.