Ultrafast Mapping of Subcellular Domains via Nanopipette-Based Electroosmotically Modulated Delivery into a Single Living Cell.

Recently, a variety of strategies have been developed for single-cell detection. However, the precise probing of the given area at single-cell level is still a challenge. Here, we put forward a rapid and targeted imaging approach for the mapping of subcelluar domains, which realizes the precise injection of multifluorescence into a single living cell via an ultrasmall quartz capillary nanopipette (∼100 nm) and can successfully transport different fluorescent probe molecules to the pointing subcellullar area around the tip in the cytoplasm within 20 s. This method is also applied for monitoring the loss of intracellular mitochondrial membrane potential under the treatment of metformin in a single MCF-7 breast cancer cell. The major driven force in the nanopipette, electroosmotic flow, is evaluated by a theory calculation method and finite element simulations, and the solution indicates a confined solute distribution profile around the tip within the working range. Overall, the nanopipette approach realizes the precise and simultaneous delivery of multiple probe molecules into the single living cell through the electroosmotically modulated, nondestructive, and one-step injection, which is especially powerful and convenient for multichannel single-cell imaging and monitoring, indicating favorable potential for understanding, monitoring, and controlling the biological processes from the single cell to subcellular organelles.