(569e) Lipid Membranes On Nanoporous Metal Films

Black lipid membranes(1), liposomes(2), and solid supported membrane (SSM) (3,4) are the common model lipid systems used to mimic cell membranes and to study the incorporation of transmembrane proteins. Of all the systems, SSMs exhibit enhanced stability and offer a solid platform to study transport mechanisms involved in transmembrane proteins (TMP), embedded within the bilayers.(5) However, the thin cushion of water (less than a nm) between the supported lipid membrane and the substrate precludes the incorporation of functional TMPs on solid supports and still remains the biggest challenge. (3) An ideal lipid membrane on the substrate should also retain its fluidity, and also offer extremely high impedance in order to study the incorporation of TMPs.
    Nanoporous metals have received significant attention over the last decade due to their unusually high surface area per unit volume, exceptional mechanical strength, and ease of synthesis (6-10). However, due to the fragile nature and non-uniform pore size distribution of the nanoporous Au films the goal to form lipids bilayers has been precluded till now. We have developed a new procedure to synthesize exceptionally uniform nanoporous gold (10-20 nm pore size) and platinum electrodes by dealloying a co-deposited Metal-Si thin film. Based on these exceptional properties of the nanoporous gold including porosity, conductivity and stability, we have developed a simple technique to form fluid, stable and resistive bilayers on nonporous metal/silicon substrates as well as nanoporous metal substrates.
 Fluorescence recovery after photo-bleaching (FRAP) measurements was performed to determine the fluidity of lipid membranes on these substrates. Impedance studies reveal the formation of a resistive lipid membrane on these substrates. The resultant lipid bilayers were modeled using a Zview software with R(RC)(RC) circuit diagram.

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