Comparative analysis of photocaged RGDS peptides for cell patterning.

Photocaged RGDS is a cell nonadhesive tetrapeptide that can be activated with light to become cell-adhesive. Such molecules can find useful applications in controlling cell adhesion for biological study, drug development, and in forming dynamic, adhesion-controlled biomaterials. Herein, we prepared RGDS peptide photocaged either on the Arg-Gly backbone amide nitrogen atom (R[-]GDS) or Asp side chain carboxyl (RG[D]S). A critical comparison of the peptides' chemical and physiological properties relevant for biological applications was carried out. It was observed that RG[D]S was synthesized more readily via automated solid-phase synthesis, underwent uncaging with a rate constant 3-fold higher than R[-]GDS, and was more stable in aqueous solution. Automated docking studies were performed to examine the interactions of various caged RGDS peptides with cell surface integrin receptor to identify suitable locations for the photosensitive 2-nitrobenzyl (NB) group for biological applications. A competitive binding ELISA method compared the ability of various peptides to bind to α(V)β(3) cell integrin receptors and the data were found to be consistent with the modeling predictions. Finally, the application of our caged RGDS peptides in controlling cell adhesion to form cell patterns on a hydrogel material was presented.