Super-resolution microscopy allows scientists to view single molecules and study their complex interactions. However, because of the high cost and specialized knowledge required to operate super-resolution microscopes, the technology is currently inaccessible to many labs.
Now, researchers working at the Ludwig Maximilian University and the Max Planck Institute report that they have developed a new technique adapted to work in confocal microscopes, putting super-resolution in the reach of many more labs. Their findings were published yesterday in Nature Communications.
The group developed a method called DNA-PAINT, a molecular imaging technology that relies on DNA-DNA interactions to accurately localize fluorescent dyes with super-resolution. This approach attaches a DNA “anchor strand” to the molecule of interest. A complementary, dye labeled DNA “imager strand” attaches to the anchor and produces a fluorescent signal that can distinguish molecules only nanometers apart from each other.
While the first iteration of this method could visualize biomolecules, such as proteins, in fixed cells at fixed close distances, the researchers sought to adapt it to investigate molecules deep inside of cells.
In the current study, the team was able to adapt this technology to visualize a variety of molecules including proteins, RNAs and DNA throughout the entire depth of whole cells at super resolution using a Spinning Disk Confocal (SDC) microscope.
"This addition can be easily customized by manufacturers of SDC microscopes; so we basically implement super-resolution microscopy without complex hardware changes to microscopes that are generally available to cell biologists from all venues of biomedical research. The approach thus has the potential to democratize super-resolution imaging throughout whole cells and tissues," said Ralf Jungmann, Ph.D., a Professor at the Ludwig Maximilian University (LMU).
Image: The researchers used their SDC-PAINT method to visualize the network of cytoskeletal microtubule filaments (green) and their proximity with two additional proteins called TOM20 (red) and HSP60 (blue). Each image shows the proteins in a different plane of the cell starting from the top, and the magnified images on the bottom compare the resolution achieved with SDC-PAINT (left) to that possible with conventional confocal microscopy (right). Image courtesy of: Florian Schueder, MPI/LMU.