Biomembranes are complex, heterogeneous, dynamic systems playing essential roles in numerous processes such as cell signaling and membrane trafficking. Model membranes provide simpler platforms for studying biomembrane dynamics under well-controlled environments. Here we present a modified polymer lift-off approach to introduce chemical complexity into biomimetic membranes by constructing domains of one lipid composition (here, didodecylphosphatidylcholine) that are surrounded by a different lipid composition (e.g., dipentadecylphosphatidylcholine), which we refer to as patterned backfilled samples. Fluorescence microscopy and correlation spectroscopy were used to characterize this patterning approach. We observe two types of domain populations: one with diffuse boundaries and a minor fraction with sharp edges. Lipids within the diffuse domains in patterned backfilled samples undergo anomalous diffusion, which results from nonideally mixed clusters of gel phase lipid within the fluid domains. No lateral diffusion was observed within the minor population of domains with well-defined borders. These results suggest that, while membrane patterning by a variety of approaches is useful for biophysical and biosensor applications, a thorough and systematic characterization of the resulting biomimetic membrane, and its unpatterned counterpart, is essential.
Bibliographical noteFunding Information:
We thank Prof. Ahmed A. Heikal (Penn State Bioengineering) and Angel M. Davey (Penn State Chemistry) for helpful comments on this manuscript. This work was supported, in part, by The Pennsylvania State University, the Penn State Materials Research Institute, the Penn State MRSEC under NSF grant DMR 0213623, and the Center for Optical Technologies, which is supported by the Commonwealth of Pennsylvania. This publication was also supported by the Pennsylvania State University Materials Research Institute Nano Fabrication Network and the National Science Foundation Cooperative Agreement No. 0335765, National Nanotechnology Infrastructure Network, with Cornell University. Additional acknowledgement is made to the Donors of the American Chemical Society Petroleum Research Fund, National Institutes of Health grant AG030949, National Science Foundation grant MCB 0718741, and Avanti Polar Lipids, Inc. for partial support of this research.
- Fluorescence correlation spectroscopy
- Lateral diffusion
- Lipid bilayer