Advanced microscope technology now lets us view objects at the nanoscale, meaning, when it comes to biology, we can see details of living cells that were never possible before. But doing that comes with a few requirements that have been fairly limiting. For instance, you have to be able to pack a lot of fluorescent dye into the object you want to see and you need that dye to be really stable. Typically, those sorts of dyes grab onto proteins in the object, but proteins are often not distributed densely enough, limiting how much dye can be introduced. Also, these fluorescent dyes tend to bleach out really quickly, only giving researchers a few seconds of imaging time.