The authors present a method for spreading large (> 100 mm2) cell membrane fragments across nanoapertures in planar supports. Electron-beam and focused-ion-beam lithog. were used to fabricate arrays of 50-600 nm diam. holes in free-standing silicon nitride (SiN) solid films 100-500 nm thick. By pressing adhering live cells onto the nanostructured SiN surface and then removing them, planar cell membrane sheets (CMSs) were transferred in a well-defined orientation onto the SiN support. The authors demonstrate the accessibility to both extracellular and intracellular surfaces of CMSs by targeting membrane constituents side-specifically with fluorescent markers. The authors' approach is of interest for studying ligand-receptor interactions using optical, elec., and scanning probe techniques at the single-mol. level. [on SciFinder (R)]