Authors: J. Choi, A. Roychowdhury, S. Park
Affilation: Louisiana State University, United States
Pages: 529 - 532
Keywords: UV imprint, free-standing polymer membrane, lipid adsorption, conductivity
We will show a technology utilizing all parallel processes to produce free-standing polymer membranes with perforated pores down to ~ 100 nm diameter and use of the membrane structure to study adsorption of a lipid, 1,2-Diacyl-sn-Glycero-3-Phosphocholine. For the fabrication, either thermal- or UV-imprint process was combined with a sacrificial layer technique to get a clean and fully released mechanically stable membrane. We found that UV imprint was more suitable than using thermal imprint because it was able to embody high aspect ratio nanopores at a low imprint temperature and pressure, alleviating thermal stress. In addition, cross-linking of the SU-8 during UV-curing provided enough mechanical strength for the membrane to remain free-standing. Upon exposure to the lipid solution, lipid vesicles preferentially adsorb at the pore sites in the membrane. However, when the surface was treated with poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) prior to the lipid adsorption, a weaker fluorescence signal was observed. This indicates that the PLL-g-PEG tends to prevent the vesicle formation of the lipids, which can give insight to the bilayer formation at the pore sites. We will also demonstrate in-situ conductivity measurements during the lipid adsorption by assembling the free-standing membrane into microchannels with electrodes.
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