Cover Image, Volume 51, Issue 18



An ornithine-based poly(ester amide) (above left) degrades more rapidly than a lysine-based PEA (below right) because it is capable of intramolecular cyclization (yellow scissors) upon light-triggered deprotection, in addition to hydrolysis (blue scissors). Nanoparticles formulated from the ornithine-based PEA thus disassemble rapidly, releasing cargo. By quantifying the amount of cyclization and ester hydrolysis, Caroline de Gracia Lux, Jason Olejniczak, Nadezda Fomina, Mathieu L. Viger, and Adah Almutairi demonstrate on page 3783 that only the polymer capable of forming a 6-membered ring cyclizes. This work introduces intramolecular cyclization as an efficient mechanism that can be incorporated into other polymeric materials for on-demand degradation.