Visible Light Activation of Nucleophilic Thiol-X Addition via Thioether Bimane Photocleavage for Polymer Cross-Linking.

On-demand photo-uncaging of reactive thiols have been employed in engineering biomaterial scaffolds for regulation of cellular activities. A drawback of the current photo-uncaging chemistry is the utilization of high energy UV light or 2-photon laser light, which may be harmful to cells and cause undesired side reactions within the biological environment. We introduce an effective approach for the caging of thiol using monobromobimane, which can be removed under irradiation of light at λ = 420 nm and in the presence of electrophiles, such as acrylate, propiolate and maleimide, for trapping of the newly release thiol. This chemical approach can be used in visible light-induced polymer coupling and cross-linking for the preparation of cell-laden hydrogels.