Figure 1. Mitochondrial nanobiopsy.

Nanobiopsy is carried out using a nanopipette, filled with organic solvent, that is incorporated into a Scanning Ion Conductance Microscope (SICM) system which consists of an amplifier, that modulates and detects extremely small changes in current, as well as piezo motors that allow for highly precise movement of the nanopipette to and within the area of interest. This can be used with cultured cells ( a– c) or in tissue ( d– f). ( a, d) To function, the SICM requires the nanopipette to be immersed in an aqueous solution. Whilst being lowered, the SICM system constantly measures the current through the nanopipette tip. If the current magnitudes drops below a predetermined threshold, this will result in negative feedback causing the nanopipette to stop typically within 1µm of the cell of interest. At this point the nanopipette be lowered at high speed to penetrate the cell membrane, whilst a small positive voltage (200mV) is applied to prevent premature aspiration of the cytosolic components. ( b, e) Once within the cell and at the area of interest, application of a small voltage (-200mV) allows for the aspiration of mitochondria within the cytosol as a result of the phenomenon of electrowetting. ( c, f) After successful aspiration of mitochondria, reapplication of a positive voltage (100mV) prevents further aspiration but allows retention of the collected sample. The sample can then be transferred to a collection vessel where the sample can be expelled at a higher voltage (1V).