Reusable magnetic nanocluster coated with poly(acrylic acid) and its adsorption with an antibody and an antigen

ABSTRACTThe synthesis of negatively charged magnetite nanoclusters grafted with poly(acrylic acid) (PAA) and their application as reusable nanosupports for adsorption with antibodies and antigens are presented in this article. They were facilely prepared via the free‐radical polymerization of PAA in the presence of functionalized magnetite nanoparticles to obtain highly negative charged nanoclusters with a high magnetic responsiveness and good dispersibility and stability in water. According to transmission electron microscopy, the sizes of the nanoclusters ranged between 200 and 500 nm, without large aggregation visually observed in water. The hydrodynamic size of the nanocluster consistently increased with increasing pH of the dispersion; this indicated its pH‐responsive properties, which was due to the repulsion of the anionic carboxylate groups in the structure. This nanocluster was successfully used as an efficient and reusable support for adsorption with anti–horseradish peroxidase antibody. It preserved higher than a 97% adsorption ability of the antibody after eight reuse cycles; this signified the potential of this novel nanocluster as a reusable support in the magnetic separation applications of other bioentities. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2018,135, 46160.