Photoremovable Protecting Groups

Abstract

Photoremovable protecting groups (PPGs) (also often called photocages in the literature) are used for temporary inactivation of biologically active substrates. By photoirradiation the PPG could be cleaved off and the biological activity could be restored on-demand, with a high spatiotemporal precision. The on-site liberation of the biologically active substrate could be exploited for studying dynamic biological processes or for designing targeted pharmacological interventions in vitro or in vivo. Several chemical scaffolds have been described and tested as PPGs, operating at different wavelengths. The scope of potential substrates is very broad, spanning from small molecules to proteins. In a wider context, PPGs could be used for the design of various light-responsive materials as well, for diverse applications.

Excitation Wavelength-Dependent Photochemistry

“…The molecules combining a protecting group (such as coumarin (34)) covalently linked to bioactive compounds (i.e., the caged species, morphine (35)), are totally inactive biologically. Irradiation with poly-or monochromatic light removes the protecting group and uncages the bioactive molecule [116].…”