Single-cell force spectroscopy of the interaction between P. aeruginosa and hydrophobic substrates. (a, Inset) To quantify single-cell adhesion forces, living P. aeruginosa bacteria (blue) were attached on polydopamine-coated colloidal probes (pink). (a,c) Adhesion force histograms, (b,d) rupture length histograms, and representative retraction force profiles obtained by recording multiple force–distance curves between three different WT cells (red, green, and blue) and hydrophobic substrates at 100 ms contact time (a,b; n = 495, 957, and 442 curves for each cell) and 1.1 s contact time (c,d; n = 396, 177, and 863 curves). The inset in (b) shows an enlarged view of the force plateau signatures. The curves were obtained using a maximum applied force of 250 pN and approach and retraction speeds of 1.0 μm s–1.