Successfully interfacing enzymes with polymers can afford new plastics with programmable depolymerization at the material’s end-of-life; however, achieving depolymerization down to the polymer’s small molecule building blocks, and maintaining enzymatic latency during material usage, requires controlled solid-state biocatalysis. Embedding enzyme microparticles is known to speed up polyester degradation, but compromises host properties during usage and unintentionally accelerates the formation of microplastics with partial polymer degradation due to uncontrollable random chain scission. Here we show that by nanoscopically embedding enzymes with deep active sites, semi-crystalline polyesters can be degraded on-demand primarily via chain end-mediated processive depolymerization while maintaining programmable latency and material integrity during usage, akin to polyadenylation-induced messenger RNA decay. Processive depolymerization can also be achieved by manipulating shallow active sites via transient interactions with polymeric enzyme protectants without engineering the enzyme sequence. Furthermore, understanding the role of crystalline lamellae thickness and geometric properties, which are modified by the polymeric protectant, enables near complete depolymerization of recalcitrant polyesters by exploiting synergistic enzyme mechanisms. Our work provides molecular guidance towards enzyme–polymer pairing and the selection of enzyme protectants to modulate substrate selectivity and optimize biocatalytic pathways.

Near complete depolymerization of polyesters with nano-dispersed enzymes

ACS Fall 2021

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