Fabrication of a thermoresponsive biohybrid double hydrophilic block copolymer by a cofactor reconstitution approach.

The fabrication of a thermoresponsive biohybrid double hydrophilic block copolymer (DHBC) by a cofactor reconstitution approach is reported. Poly(N-isopropylacrylamide) (PNIPAM) bearing a porphyrin moiety at the chain terminal, PPIXZn-PNIPAM, is synthesized by the combination of ATRP and a click reaction. The subsequent cofactor reconstitution process between apomyoglobin and PPIXZn-PNIPAM affords well-defined myoglobin-b-PNIPAM protein-polymer bioconjugates. Behaving as typical responsive DHBCs, the obtained myoglobin-b-PNIPAM biohybrid diblock copolymer exhibits thermo-induced aggregation behavior in aqueous solution as a result of the presence of the thermoresponsive PNIPAM block, as revealed by temperature-dependent transmittance, dynamic laser light scattering measurements, transmission electron microscopy, and scanning electron microscopy. This work represents the first report of the preparation of responsive biohybrid DHBCs by the cofactor reconstitution process.