Site-Specific Labeling of Affimers for DNA-PAINT Microscopy.

Optical super-resolution techniques allow fluorescence imaging below the classical diffraction limit of light. From a technology standpoint, recent methods are approaching molecular-scale spatial resolution. However, this remarkable achievement is not easily translated to imaging of cellular components, since current labeling approaches are limited by either large label sizes (antibodies) or the sparse availability of small and efficient binders (nanobodies, aptamers, genetically-encoded tags). In this work, we combined recently developed Affimer reagents with site-specific DNA modification for high-efficiency labeling and imaging using DNA-PAINT. We assayed our approach using an actin Affimer. The small DNA-conjugated affinity binders could provide a solution for efficient multitarget super-resolution imaging in the future.