Infrared Nanoscopy of Alive Biological Cell Surfaces

We report progress towards sealing alive cells in their native, wet environment by single-layer graphene, where graphene stabilizes the cell by tightly conforming with its surface and thus enables topographic AFM maps of the cell's surface. Furthermore, graphene's transparency to infrared near-fields enables local chemical recognition, at nominally 20-nm spatial resolution, by scattering scanning mid-infrared microscopy (s-SNOM) and spectroscopy (nano-FTIR). Here we demonstrate first infrared nanoscopy results of the surface of native E. Coli cells that show spatial and spectral contrasts. Our study opens a new door into characterizing subcellular structures and components of cells and of fresh tissue sections. Infrared nanoscopy is certainly free of any need for labelling as in super-resolution fluorescence microscopy, and free of fixation and metallization procedures as in electron microscopy that kill and distort cells.