(A) Molecular graphics representation of an IKVAV PA nanofiber indicating the chemical structure and location of DPH used as a probe in fluorescence depolarization measurements (top); bar graph of fluorescence anisotropy of IKVAV PA solutions (error bars correspond to 3 independent experiments; n.s. no significant, ***P<0.0001, one-way ANOVA with Bonferroni). (B) Chemical structure of the IKVAV peptide sequence highlighting the K residue probed by NMR (top); bar graphs of the K relaxation time for the different IKVAV PAs investigated (error bars correspond to 3 runs per condition; ***P<0.0001 vs IKVAV PA1, #P<0.05, ###P<0.0001 vs IKVAV PA2 and +P<0.05, +++P<0.0001 vs IKVAV PA5, one-way ANOVA with Bonferroni). (C) Differentiation conditions used for hNPCs. (D) Representative micrographs of hNPCs treated with IKVAV PA1, PA2, PA4 and PA5; NESTIN-stem cells (red), ITGB1-receptor (green), and DAPI-nuclei (blue). (E) WB results of ITGB1, p-FAK, FAK, ILK, and TUJ-1 in hNPCs treated with laminin and the various IKVAV PAs. (F) Representative confocal micrographs of hNPCs treated with IKVAV PA1, PA2, PA4 and PA5; NESTIN-stem cells (red), SOX-2-stem cells (green), TUJ-1-neurons (white), and DAPI-nuclei (blue). (G, H) Bar graphs of the percentage of SOX-2+ and NESTIN+-stem cells (G) and TUJ-1+ cells (H) treated with the various IKVAV PAs (error bars correspond to 3 independent differentiations; **P<0.01, ***P<0.001 vs IKVAV PA2 and ##P<0.01, ###P<0.001 vs IKVAV PA5, one-way ANOVA with Bonferroni). (I) Fluorescence anisotropy (left) and K residue relaxation times (right) obtained for IKVAV PA2 nanofibers in the absence (No Ca2+) or presence (Ca2+) of calcium ions (***P<0.001, student’s t-test). (J) WB results of ITGB1, p-FAK, FAK, ILK, TUJ-1 in hNPCs treated with IKVAV PA2 in the absence (−) or presence (+) of Ca2+. Scale bars: (D) 10 μm, (F) 100 μm.