Preparation and self-assembly of Au nanoparticles coordinated Fe₃O₄ graft block copolymer multifunctional nanohybrids with pH, electrochemical and magnetic stimuli responsiveness

Multi-component block copolymer nanohybrids consisting of Fe₃O₄ nanoparticles and poly(acryloyloxyethyloxyl 1-mercaptohemisuccinate) and poly(methacrylic acid) (PMAA) blocks were synthesized via the surface-initiated atom transfer radical polymerization, followed by the esterification with d,l-mercaptosuccinic acid. The block copolymer nanohybrids were coordinated with Au nanoparticles (Au NPs) through pendent thiol groups to form Au NPs coordinated Fe₃O₄ graft block copolymer nanohybrids. Fluorescent spectrometry, TEM and SEM findings indicated that these block copolymer nanohybrids could self-assembled and form globular core–shell nanomicelles, and their critical micelle concentrations decreased with the decrease in the length of PMAA chains and the incorporation of Au NPs. Zeta potential measurements signified that the copolymer nanohybrids possessed significantly high stability. DLS results indicated that hydrodynamic diameters of the copolymer nanohybrids distributed within the scope of 85–155 nm, hinging on the length of the graft chains and the complexation of Au NPs. The hybrid block copolymer nanomicelles exhibited pH, electrochemical and magnetic responsiveness, with pH transition points at 5.3–5.9. The incorporation and the loading percentage of Au NPs improved the reversibility of the electrochemical response and plasmon resonance. The block copolymer nanohybrids were superparamagnetic and were expected to broaden their applications by virtue of the multi-component combination and the resulting multifunctionality.