Particle/fluid interface replication as a means of producing topographically patterned polydimethylsiloxane (PDMS) surfaces for deposition of lipid bilayers

Microstructured surfaces are common in many materials applications such as microcontact printing,[1,2] biomimetic arrays, [3]controlled-wetting surfaces,[4] superhydrophobic surfaces, [5] and self-cleaning surfaces[6]among others. The majority of strategies for surface fabrication utilize some form of photolithography to achieve patterning. Photolithographic patterning is essentially two-dimensional;[1–4]it does not allow control over geometric parameters in the third dimension such as the surface profile and curvature (the topography) of fabricated features. To overcome the inherent limitations of photolithography, the fabrication of topographically patterned substrates for applications of supported lipid bilayers[7, 8]requires a combination of microfabrication techniques: photolithography followed by anisotropic plasma dry etching and wet oxide etching,[7] or chemical vapor deposition followed by photolithography and chemical etching.[8] These pioneering methods, while successful in producing topographically patterned surfaces capable of imposing gradients of curvature on supported bilayers, are technically complex and require costly clean room or microfabrication facilities. An alternative method is thus desirable, particularly since there is intense interest in the role of curvature in the thermodynamics and dynamics of lipid bilayers[7–11]and membrane proteins[12–14]in the wider fields of biology and physics.