Bioinspired single bacterial cell force spectroscopy.

We developed a method for preparing live bacterial cell probes for atomic force microscopy (AFM) using a bioinspired polydopamine wet adhesive. Microscopic examinations with bacterial and yeast cells indicated that cells were successfully glued to the end of the AFM cantilevers and remained viable for the duration of the force measurements. Interaction forces measured with live single-cell microorganism probes differed markedly from those obtained with glutaraldehyde-fixed microorganism probes. Interaction forces between live cell probes and quartz surfaces involved both repulsive steric forces and multimodal weak adhesion forces, which were attributed to the soft exocellular polymeric layers and the heterogeneity of the cell membrane surfaces.