The synthesis and self-assembly of bioconjugates composed of thermally-responsive polymer chains and pendant lysozyme molecules

Recently, the synthesis of bioconjugates combining tunable properties of polymers with the functionalities of proteins has aroused great interest in the biomaterials community. In this research, thermally-responsive polymer chains with pendant lysozyme molecules were prepared via a “grafting to” approach. The enzyme molecules were anchored to the polymer backbones through covalent bonds. The influences of the number of pendant enzyme molecules and the salt concentration on the thermal-responsive properties of the bioconjugates were investigated. With an increase in the number of pendant lysozyme molecules, the cloud point (TCP) shifts to a higher temperature. The TCPs of the bioconjugates decrease with an increase in the salt concentration. In aqueous solutions, the bioconjugate molecules make core–shell structures at a temperature below TCP due to the unfavorable interaction between the polymer chains and the enzyme molecules. The bioconjugates are able to self-assemble into mesoglobules at temperatures above TCP. The secondary structure and bioactivity of the enzyme on the assembled structures were basically maintained.