Exploiting nanofibrous chitin microspheres as heterogeneous photocatalysts for high throughput PET-RAFT polymerization and bioconjugation

Abstract High throughput approaches have become increasingly prevalent in the interdisciplinary space of polymer chemistry and biomedical engineering for the screening of polymer structure and biological activity. However, the syntheses of bioconjugates at high monomer dilutions and in a high throughput format are still challenging as there are typically limited quantities of the biological substrates available and cumbersome procedures for catalyst removal. Chitin is one of the most abundant natural polymers derived from seafood waste. This has inspired us to modify chitin for fabricating catalyst support. In this contribution, nanofibrous chitin (NC) microspheres as the matrix were employed for surface conjugation of eosin Y-bound copolymers via activated ester-amine reaction to prepare NCPNIEY microspheres. These microspheres hold great prospects for enabling high throughput polymerizations that possess advantages of photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization such as low-energy input, ultralow catalyst dosages and spatiotemporal control over chain propagation. The robustness of the NCPNIEY microspheres mediated protocol was demonstrated in the well-structured polymer syntheses and protein-polymer bioconjugation alongside catalyst-recycling experiments in multi-well plates. Raising the temperature of the reaction mixture to 37 °C caused segregation of the NCPNIEY microspheres in a hydrophilic-to-hydrophobic transition, allowing for the rapid purification of the protein-polymer bioconjugates without compromising protein activity. This work provides a versatile approach and useful insights for bioconjugate manufacturing in a high throughput format owing to simplified purification and improved sustainability.