Improved route to PAHA polyesters

Abstract

Poly(α-hydroxy acid) (PAHA) polyesters form products such as cell-penetrating nanoparticles for drug and gene delivery and biodegradable sutures and implants, but they’ve been hard to synthesize. Rong Tong and Quanyou Feng at Virginia Tech now report a polymerization that could make them more accessible (J. Am. Chem. Soc. 2017, DOI: 10.1021/jacs.7b01462). PAHAs can be customized by varying the side chains of the lactide and glycolide monomers used to make them. But adding those monomer side chains is difficult, and synthesizing PAHAs from lactides and glycolides requires multistep, low-yield reactions. In 2006, Didier Bourissou of Paul Sabatier University and coworkers showed that PAHAs could also be made from O-carboxyanhydride (OCA) monomers, which are much easier to prepare and modify. But OCA polymerizations were slow and had undesired side reactions, uncontrolled stereochemistry, and broad and unpredictable molecular weight distributions. In Tong and Feng’s new approach to OCA polymerization, a photo...