"On-Off" RGD Signaling Using Azobenzene Photoswitch-Modified Surfaces

Photoresponsive surfaces were developed by modifying glass slides with switchable Gly-Arg-Gly-Asp-Ser (GRGDS) peptides to investigate light-controlled cell adhesion. The GRGDS peptide sequence was attached to an azobenzene moiety and then "clicked" to silanized glass substrates. The photoresponsive behavior of such cell-instructive materials (CIMs) was first checked by contact angle technique and by recording local changes in wettability owing to the isomerization of the azobenzene domain upon light stimulus. "On-off" switching was observed for at least five cycles when illuminated consecutively with UV and visible-light sources. Finally, cell-adhesion studies with human umbilical vein endothelial cells (HUVECs) validated our system as an effective light-responsive CIM platform and the possibility of dynamically controlled cell adhesion in situ was envisioned.