Synthesis of lipase-polymer conjugates by Cu(0)-mediated reversible deactivation radical polymerization: polymerization vs. degradation

Polymerization-induced self-assembly (PISA) has evolved as a facile pathway for the in situ formation of polymeric nanomaterials with unique morphologies. However, aqueous PISA by atom transfer radical polymerization (ATRP) for the generation of protein-based nanoassemblies is still challenging. In this research, Candida antarctica lipase B (CALB) is modified as the macroinitiator for Cu(0)-mediated reversible deactivation radical polymerization (Cu(0)-RDRP) of both hydrophilic and hydrophobic monomers in water or water/methanol mixtures. Different acrylamides and acrylates are successfully polymerized in the presence of lipase-based macroinitiators under mild reaction conditions and it is found that the lipase-catalyzed hydrolysis of ester bonds from poly(acrylates) is very significant. The PISA of lipase-hydrophobic polymer conjugates could directly generate spherical nanoparticles in aqueous solution without further processing. Activity tests further demonstrate preservation or even a significant increase of the enzymatic activity for the conjugates, indicating the potential application of aqueous PISA in protein delivery and enzyme immobilization.