Light-Controlled Selective Disruption, Multilevel Patterning, and Sequential Release with Polyelectrolyte Multilayer Films Incorporating Four Photocleavable Chromophores

We report photolabile polyelectrolyte multilayers (PEMs), produced by the layer-by-layer (LbL) approach, which comprise commercially available photoinert polyanions and photolabile polycations. Photochemical degradation of synthetic photolabile polycations renders these PEMs soluble in near neutral aqueous solutions. Taking advantage of the vast array of available photocleavable chromophores that absorb different wavelengths of light with different quantum yields of photolysis, we designed four photolabile polycations (P1-P4), each containing different photocleavable groups: dialkylaminocoumarin group (P1), different nitrobenzyl groups (P2 and P3), and methoxyphenacyl group (P4). PEMs containing different chromophores dissolved selectively under different irradiation conditions. Sequential photocontrolled dissolution of multilayers from a hybrid, quadruple-compartment LBL film was demonstrated using this approach, as was photolithographic patterning of films at multiple heights using different irradiation conditions and photomasks. We also demonstrated irradiation-selective, light-triggered release of guest fluorophores from microspheres coated with such PEMs.