Figure 1.
FluidFM-based single-cell force spectroscopy.
Schematic view of the experimental principle. (A) Cell targeting and immobilization to the cantilever through the application of under pressure. (B) Single-cell force spectroscopy and subsequent release of the measured cell.
Figure 2.
Representative example of the force-distance (F–D) curves that were obtained with a C. albicans cell on DDP (A) and a HeLa cell on fibronectin (B).
The data show a force range between 20 and 800 nN (red: approach, blue: retraction curve). The maximal adhesion force was computed as the minimum force value (FAdh). The work performed by the Z-piezo during the detachment process (WAdh) was calculated as the area below the baseline (shaded area). The distance (d) is the distance required for the complete separation of the yeast cell from the substrate.
Figure 3.
The adhesion forces depend on the retraction speed and the contact time.
(A) Dependence of the adhesion force on the retraction speed with a constant contact time of 30 s. The data were obtained with a C. albicans cell on DDP (red) and glass (blue). (B) Dependence of the adhesion force on the contact time. The data were obtained using a C. albicans cell on DDP at three different retraction speeds: 300 nm/s (black), 500 nm/s (red) and 2000 nm/s (blue). Between 5 and 10 F–D curves were randomly recorded per condition. The data shown represent the mean ± standard error. The results in A and B demonstrate that repeated measurements with the same cell do not exhibit a high variance in the adhesion forces.
Figure 4.
Adhesion of C. albicans to moderately hydrophobic substrates.
(A) Time-dependent comparison of the maximal adhesion forces at 23 and 37°C. (B) Correlation of FAdh and WAdh at 23°C throughout the 9 hours of adhesion; R2 = 0.96. The analysis in (A) involved the recording of at least 7 F–D curves per condition and time frame. The data represent the mean ± standard error.
Figure 5.
Maximal adhesion forces of yeast and mammalian cells to abiotic substrates.
(A) Comparison of the maximal adhesion forces of C. albicans and S. cerevisiae to hydrophobic DDP and hydrophilic DDP-OH surfaces at 30°C after an adhesion time of 15 min. The data represent the mean ± standard error of 5–14 measurements per yeast and substrate. (B) Comparison of the maximal adhesion forces of HeLa and HEK cells to glass and fibronectin-coated substrates at 37°C after overnight contact with the cell substrate. A total of 12 and 11 HeLa cells were measured on the glass and fibronectin substrates, respectively, whereas 8 and 9 HEK cells were measured on the glass and on fibronectin substrates, respectively. The data represent the mean ± standard error. The force spectroscopy data, which were obtained when the cell was detached from the cantilever, were not included in the mean and error calculations.
Table 1.
Comparison of the maximal adhesion forces of all cell types on different substrates.
Figure 6.
Comparison of adhesion forces of C. albicans wild type and Δhgc1 cells at 37°C.
(A) Distribution of adhesion forces of C. albicans wild type and (B) Δhgc1 cells on moderate hydrophobic substrate. Yeasts were grown at the same temperature the experiment was performed.