Abstract
We present measurements of the in situ, microscopic architecture of a self-assembled bilayer at the interface between a regularly nanopatterned surface and an aqueous sub-phase using neutron reflectometry. The substrate is patterned with a rectangular array of nanoscale holes. Because of the high quality of the pattern, using neutron reflectometry, we are able to map the surface-normal density distribution of the patterned silicon, the penetration of water into the pattern, and the distribution of a deposited film inside and outside of the etched holes. In this study, 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) single bilayers were deposited on the hydrophilic patterned surface. For bilayers deposited either by vesicle fusion (VF) or by the Langmuir-Schaefer (L-S) technique, the most consistent model found to fit the data shows that the lipids form bilayer coatings on top of the substrate as well as the bottoms of the holes in an essentially conformal fashion. However, while there is a single bilayer on the unetched silicon surface, the lipids coating the bottoms of the holes form a complex bimodal structure consistent with a rough surface produced by the etching process. This study provides insight into film transfer both outside and inside regular nanopatterned features.
Original language | English |
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Pages (from-to) | 784-794 |
Number of pages | 11 |
Journal | Nano Research |
Volume | 6 |
Issue number | 11 |
DOIs | |
State | Published - Oct 2013 |
Funding
The authors would like to thank C. Halbert for her assistance with the Liquids Reflectometer and J. Ankner for useful discussions on the NR measurements. MA was supported by the NanoPower Africa Project funded by the United States Agency for International Development (USAID) through the Higher Education for Development (HED) office. The research at Oak Ridge National Laboratory’s Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. A portion of this research was also conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.
Keywords
- lipid
- nanopattern
- neutron reflectivity
- self-assembly
- thin film