Thermoresponsive giant biohybrid amphiphiles

A series of random copolymers of various lengths was prepared by atom transfer radical polymerisation (ATRP) using two acrylate monomers with short pendant ethylene glycol side chains (ethylene glycol methyl ether acrylate, EGMEA, and methoxy ethoxy ethyl acrylate, MEEA). The end group was converted to an azide to enable bioconjugation through copper-catalysed azide-alkyne cycloaddition (CuAAC). All polymers were found to be thermoresponsive, with a cloud point between 25 and 35 degrees C depending on their molecular weight. They were conjugated to enhanced green fluorescent protein (EGFP) functionalised with a single alkyne moiety, as seen by fast performance liquid chromatography (FPLC) and gel electrophoresis (SDS-PAGE). The resulting biohybrid amphiphiles were thermoresponsive. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to study their self-assembly at elevated temperatures, and they were found to form spherical structures with a diameter of approximately 60 nm upon slow heating.