Polymer brush-modified magnetic nanoparticles for His-tagged protein purification.

Growth of poly(2-hydroxyethyl methacrylate) brushes on magnetic nanoparticles and subsequent brush functionalization with nitrilotriacetate-Ni(2+) yield magnetic beads that selectively capture polyhistidine-tagged (His-tagged) protein directly from cell extracts. Transmission electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis, and magnetization measurements confirm and quantify the formation of the brushes on magnetic particles, and multilayer protein adsorption to these brushes results in binding capacities (220 mg BSA/g of beads and 245 mg His-tagged ubiquitin/g of beads) that are an order of magnitude greater than those of commercial magnetic beads. Moreover, the functionalized beads selectively capture His-tagged protein within 5 min. The high binding capacity and protein purity along with efficient protein capture in a short incubation time make brush-modified particles attractive for purification of recombinant proteins.