Manipulation of cell adhesion using photo-responsive substrates. (A) Photocleavage to induce the release of non-adhesive BSA protein to enable subsequent immobilization of cell-adhesive FN. (B) Photoisomerization of azobenzene-containing SAMs for masking/demasking of cell adhesion RGD ligand within the PEG layer. (C) Photoreversible assembly/disassembly of β-CD-azobenzene host-guest complex, where the guest azobenzene is modified with cell adhesive peptide. (D) Photo-mediated isomerization of spiropyran, and thus switching the surface wettability to reversibly attach and release fibroblast L929 cells. A: [234], Copyright 2004. Reproduced with permission from American Chemical Society. B: [235], Copyright 2017. Reproduced with permission from John Wiley and Sons Inc. C: [236], Copyright 2011. Reproduced with permission from American Chemical Society. D: [174], Copyright 2014. Reproduced with permission from American Chemical Society.