Data from: Nanoaperture fabrication via colloidal lithography for single molecule fluorescence analysis

In single molecule fluorescence studies, background emission from labeled
substrates often restricts their concentrations to non-physiological
nanomolar values. One approach to address this challenge is the use of
zero-mode waveguides (ZMWs), nanoscale holes in a thin metal film that
physically and optically confine the observation volume allowing much
higher concentrations of fluorescent substrates. Standard fabrication of
ZMWs utilizes slow and costly E-beam nano-lithography. Herein, ZMWs are
made using a self-assembled mask of polystyrene microspheres, enabling
fabrication of thousands of ZMWs in parallel without sophisticated
equipment. Polystyrene 1 μm dia. microbeads self-assemble on a glass slide
into a hexagonal array, forming a mask for the deposition of metallic
posts in the inter-bead interstices. The width of those interstices (and
subsequent posts) is adjusted within 100–300 nm by partially fusing the
beads at the polystyrene glass transition temperature. The beads are
dissolved in toluene, aluminum or gold cladding is deposited around the
posts, and those are dissolved, leaving behind an array ZMWs. Parameter
optimization and the performance of the ZMWs are presented. By using
colloidal self-assembly, typical laboratories can make use of
sub-wavelength ZMW technology avoiding the availability and expense of
sophisticated clean-room environments and equipment.