Graphene-based metal-induced energy transfer for sub-nanometre optical localization

Single-molecule fluorescence imaging has become an indispensable tool for almost all fields of research, from fundamental physics to the life sciences. Among its most important applications is single-molecule localization super-resolution microscopy (SMLM) (for example, photoactivated localization microscopy (PALM)(1), stochastic optical reconstruction microscopy (STORM)(2), fluorescent PALM (fPALM)(3), direct STORM (dSTORM)(4) and point accumulation for imaging in nanoscale topography (PAINT)(5)), which uses the fact that the centre position of a single molecule's image can be determined with much higher accuracy than the size of that image itself. However, a big challenge of SMLM is to achieve super-resolution along the third dimension as well. Recently, metal-induced energy transfer (MIET) was introduced to axially localize fluorescent emitters(6-9). This exploits the energy transfer from an excited fluorophore to plasmons in a thin metal film. Here, we show that by using graphene as the 'metal' layer, one can increase the localization accuracy of MIET by nearly tenfold. We demonstrate this by axially localizing single emitters and by measuring the thickness of lipid bilayers with angstrom accuracy.