Abstract
First observed optically 33 years ago, single molecules have opened a new field of chemical science for observing the nanoscale. One key application is super-resolution fluorescence microscopy, which uses single-molecule imaging and on/off control of emitters to enable visualization of biological structures and behavior in fixed and live cells with resolutions down to 10-20 nm and below. One recent application addresses coronavirus infection of mammalian cells by finding where the viral RNA structures are located in the cellular context of key viral proteins and oligonucleotides. Another new thrust uses low temperature single-molecule imaging to answer this question: “In my high-resolution cyro-electron tomography (CET) cell images, where is my protein actually located?” Annotation of CET by single-molecule imaging provides an answer.