Site-Specific Polymer-Protein-Polymer Conjugates for the Preparation of Dual Responsive Multilayer Nanoparticles

Abstract

Protein-polymer-based materials demonstrate high potential in advanced applications. However, controlled combinations of multiple proteins and polymers to obtain multimaterial systems is limited due to the complexity of retaining protein structure and function and achieving high structural control for the polymers simultaneously. Here, the first combination of a rebridging agent and thiol-induced, light-activated controlled radical polymerization (TIRP) is introduced to directly enable site-specific conjugation of two different polymers to native proteins. Specifically, poly(N-isopropyacrylamide) (pNIPAM) is attached to bovine serum albumin (BSA), followed by incorporation of a new rebridging agent, and initiating a second TIRP to introduce a glycopolymer, giving highly defined pNIPAM-BSA-glycopolymer conjugates. Above the lower critical solution temperature (LCST), nanoparticles with a glycopolymer corona are formed. The addition of a glycan-specific lectin leads to the formation of a second protein corona and so-called multilayer nanoparticles. Depending on the sequence of stimuli, the particles can either undergo a step-wise or one-step disassembly. Furthermore, by controlling the ratio of binding/non-binding glycopolymers in the multilayer nanoparticles, either distinct nanoparticles or large clusters can be formed. Thus, dual-responsive multilayered polymer-protein nanoparticles are now accessible with controlled and programmable material properties such as assembly and disassembly while maintaining the protein's native structure and thus function.