Investigating Membrane Domain Dynamics using Multimodal Optical Microscopy

Abstract

Nano-membrane domains are hypothesized to play an integral role in many cell signaling pathways. Their transient nature provides for a challenging mode of analysis, therefore innovative techniques must be developed to provide insight into their underlying dynamics. By integrating dynamic holographic optical trapping (HOT) and fluorescence imaging with fluorescence correlation spectroscopy (FCS), we are characterizing membrane domain nucleation in biomimetic planar supported bilayers. The dynamic HOT system allows for the creation of multiple traps from a single light source, each of which can be controlled individually in real time. Silica microspheres were trapped and moved into arbitrary patterns for system optimization. Receptor-bound microspheres associated with nano-domains in planar supported bilayers act as handles for dynamic HOT manipulation. We hypothesize that by trapping multiple microsphere-bound receptors, the associated lipid domains will nucleate a larger domain upon interaction. Fluorescence imaging is used to visualize domain formation, and subsequent lateral diffusion of lipid species will be measured with FCS. These results should lead to new insights into domain formation in membranes.