Integrated Fluorescence and Scanning Microwave Microscopy: Nano-Imaging with “Proof of Life”

We demonstrate imaging using scanning microwave microscopy (SMM) of vital single cells in salt buffer. HeLa cells are cultured on 130 μm glass cover slips and left overnight in the incubator for optimal attachment. We verify that the cells are “alive” by measuring the membrane potential of mitochondrial using a voltage sensitive fluorescent dye (TMRE). The cells are measured capacitively at 7 GHz. We further track SMM map changes by adding digitonin-a detergent solution- to cells that would empty out cell content by creating holes on the plasma membrane. This paper represents a dramatic improvement of the technique of scanning microwave microscopy by integrating it with simultaneous fluorescence images of living cells to obtain “proof of life” via fluorescence imaging of HeLa cells which are simultaneously imaged via SMM. This integration and combination of the two techniques (fluorescence microscopy and scanning microwave microscopy) should enable the entire fluorescence bioimaging technology to be combined with SMM for simultaneous optical and SMM images of biological processes.