Fig. 8 Single-cell force spectroscopy[122]
The AFM can measure the adhesion force of individual intact living cells with high spatial and energy resolution, pico-cow-scale force sensitivity, and nanometre-scale localization accuracy. AFM has unique features: (1) it can operate in solution and observe biological structures under in situ conditions [129]. (2) it can observe individual proteins at a resolution greater than 1 nm, allowing direct observation of structural changes in individual biomolecules [128].
AFM also has limitations, such as the time-consuming and expensive measurement of bacterial adhesion using single-cell force spectroscopy. Only one cell can be characterized at a time; each cell requires a separate cantilever and must be calibrated and functionalized[122,125,127], falling short of high throughput measurements [128]. Using lectins to put fixed cells on cantilever beams is time-consuming and tends to alter the original physiological properties of the cells[126]. To obtain reliable data, a large number of force-distance curves need to be measured.