STED controlled photobleaching for sub-diffractional optical nanopatterning

Laser-assisted protein adsorption by photobleaching (LAPAP) is a versatile tool to nanopattern proteins on the micrometer scale. Sub-micron patterning is, however, difficult due to diffraction. We show that, similar to stimulated emission depletion (STED) microscopy, a depleting beam can effectively suppress LAPAP and hence is apt to locally control LAPAP in order to write sub-diffractional lines of proteins. Specifically, we attach biotinylated Atto 390 to glass substrates and incubate with Alexa 555 labeled streptavidin. The Alexa 555 is subsequently imaged with STED nanoscopy. The method is currently limited by diffusion of the biotinylated Atto 390 molecules.