DNA Origami Barcodes for Immunostaining.

In histology, immunostaining of biological samples is a gold standard for studying cellular processes, such as the expression of cell surface markers or the cellular uptake of proteins and drug molecules. Immuno-gold labeling is a commonly used technique to achieve nanometer spatial resolution, but simultaneous visualization of multiple antigens in parallel is an unresolved challenge. Herein, we demonstrate a DNA nanotechnology-based approach to label antigens in transmission electron microscopy images of tissue sections with high contrast patterns. For this, we attached gold nanoparticles to designated binding positions on DNA origami structures that act as visual "barcodes." These barcodes are then hybridized to complementary strands of DNA-modified antibodies that are bound to their respective antigens on ultrathin tissue resin sections. As a proof of concept, we demonstrate several types of barcodes and two different antibody labeling techniques that will expand the multiplexing abilities of immunostaining in a highly modular way.