Zero-mode waveguides (ZMW) are nanoapertures milled in opaque metal films with subwavelength diameters. Thanks to their strong light confinement, ZMWs have been reported to enable single molecule detection in concentrated solutions of several micromolars with enhanced fluorescence brightness. In this talk, I will describe recent applications of the ZMW concept:
The local temperature inside the ZMW can be accurately controlled by an infrared laser beam. The easy control of the temperature inside ZMWs opens their use for thermoplasmonics in confined sub-femtoliter volumes for nucleation, polymerization or crystal growth applications.
ZMWs can extend the spatial range of FRET to distances where dipole-dipole interactions would otherwise be too weak to produce detectable FRET signals. Using optimized structures a 3x FRET efficiency increase is observed at a large donor-acceptor distance of 13.6 nm, well beyond the classical Förster radius.
In the ultraviolet, ZMWs are used to monitor the autofluorescence of single label-free proteins with increased brightness, microsecond transit times and operation at micromolar concentrations. Working in the UV range is appealing to take advantage of the tryptophan fluorescence naturally present in proteins and rule out all the issues related external fluorescence labelling.