Figure 4

Surface tension of 1-decanol in different aqueous phases. Surface tension (mN/m) for 1-decanol was determined by the inverted pendant drop method in: water, decanoate 5 mM pH 11.5, decanoate 5 mM pH 11.5 mixed 1:1 with 3 M NaCl, DMEM with 10 * 7 lung cancer cells (A549, H1299 and H460) in capsules, this same supernatant mixed 1:1 with 3 M NaCl, DMEM with 10 * 7 lung cancer cells (A549, H1299 and H460 without capsules), DMEM with 10 * 7 HEK293T cells, DMEM with 10 * 7 HEK293T cells in capsules, DMEM with 10 * 7 lung cancer cells bleach treated (lung cancer cells BT: A549, H1299 and H460), DMEM, DMEM mixed 1:1 with 3 M NaCl and DMEM incubated with empty alginate capsules. All the DMEM aqueous phases were incubated for 2 days at \(3{7}^{\circ }\)C with or without cells or capsules. Decanol droplet volume was typically 10–11 \(\mu \)l. The blue bars represent for our previous transport system using decanoate as the salt-sensitive surfactant²⁰. The green bars represent the best performance of chemotaxis found in this study. The bars in orange are controls for reference. Error bars correspond to standard deviation of 10 droplets for conditions without cells, 10 droplets with three experimental replicates for HEK293T, for each lung cancer cell type and for each lung cancer cell type bleach treated (the mean from the three lung cancer cell lines is reported). Specific values for each lung cancer cell line are plotted in Fig. 5 and Supplementary Fig. S3.