Fig. 4. Receptor-ligand interactions enhance nanoparticle uptake from the ventral cell side.
a Schematic of a cell tearing off a biotin-neutravidin bound nanoparticle (AuNP) either only passivated with PEG (1) or additionally functionalized with cRGD (2) or integrin α5β1 selective ligands (3). b Confocal images of a HeLa cell (transmission) spreading and tearing off StarRed-fluorescently labeled AuNPs (magenta) from the surface at t = t0 + 70 min with ROIs 1 h post seeding. Scale bars, 10 µm. c Relative number of particles in the ROI under the cells or in a control region outside the cells over time. Data are represented as mean ± s.e.m. and fitted with two-phase decay functions. (n = 3 control regions or 19, 24, 27 cells on AuNPs (1), (2) and (3), respectively, three technical replicates, data are represented as mean ± s.e.m. and fitted with an exponential decay function). d Projected cell area normalized to t0 of cells spreading on the matrix-mimetic surfaces decorated with AuNPs 1–3 over time with exponential fits. e For the particles being actively removed by the HeLa cells, the fraction a and the off rate koff are shown as obtained by fitting from the two-phase-decay of particles in the ROI as presented in (c). (Box-plots represent median ± 95% CI with whiskers to the min and max values, **P < 0.001, ****P < 0.0001; one-way ANOVA with post hoc Tukey). Source data are provided as a source data file.