Caged Monomethyl Auristatin F (MMAF) for Cell-Specific Activation Using a 488-nm-Optimized Photolabile Group

Photolabile protecting groups (PPGs) are central tools for achieving precise spatial and temporal control of bioactive molecules in living systems. Their practical utility is critically dependent on efficient uncaging under biologically compatible conditions. Here, we report a coumarin-based PPG specifically optimized for 488 nm excitation, a ubiquitous laser line in fluorescence microscopy, enabling uncaging under irradiation conditions comparable to those used for GFP imaging. We applied the optimized PPG to cage the C-terminal carboxylate of monomethyl auristatin F (cMMAF), converting a membrane-impermeant antimitotic agent into a cell-permeant prodrug that regenerates an impermeant MMAF upon photoactivation. We showcase its utility through the light-triggered release of MMAF using irradiance typically used for imaging. We demonstrate the ability to confine the pharmacological activity of MMAF to a single cell, sparing adjacent cells (neighboring effect).