A self-crosslinking nanogel scaffold for enhanced catalytic efficiency and stability

We report the preparation of a series of polypeptoid derivatives with different side-chain functionalities by sequential photocleavage and thiol–ene reactions with high efficiency. In particular, thermo-responsive N-isopropylacrylamide (NIPAM) motifs were grafted onto polypeptoids to achieve the lower critical solution temperature (LCST) property. The incorporation of allyl groups to a block copolymer poly(ethylene glycol)-b-poly(N-(S-(o-nitrobenzyl)-thioethyl)glycine)-co-poly(N-allyl glycine) (PEG-b-PNSN-co-PNAG) enables the preparation of UV-initiated self-crosslinking nanogels for further immobilization of lipase and gold nanoparticles in aqueous solution. The obtained hybrid nanogels exhibit significantly enhanced catalytic efficiency and adjustable bioactivity as compared to the free lipase and gold nanoparticles. The hybrid nanogel showed a significantly higher conversion value of >200% compared to native lipase. By incorporating the NIPAM motifs, thermoresponsive hybrid nanogels have been fabricated and 89.8% of the residual enzymatic activities are retained at 50 °C. This work provides a facile and efficient approach to prepare multifunctional bioinspired platforms under mild conditions that offer increased catalytic efficiency and stability.