Fast and highly selective separation of His-tagged proteins by Ni2+-carrying magnetic core–shell nanoparticles

In this study, core–shell Fe3O4@Au nanoparticles with good chemical stability and tunable particle size were synthesized via Au–S bonding, which overcomes the challenges encountered for the reported preparation of Fe3O4@Au. The surface of nanoparticles was investigated by TEM, XRD, XPS, FT-IR, VSM and DLS which characterized the size, morphology, chemical lattice, elemental analysis, functional groups, magnetic strength, and size distribution. The results showed that Fe3O4@Au/NTA-Ni2+ magnetic nanocomposites were spherical with an average diameter of 469.5 nm, and superparamagnetic with saturation magnetization of 7 emu/g. The magnetic nanocomposites were directly utilized for one-step purification of His-tagged proteins from Description Escherichia coli lysate. The as-separated proteins were qualitatively validated by gel analysis and quantitatively measured by UV–visible spectroscopy. The binding capacity of Fe3O4@Au/NTA-Ni2+ towards His-tagged proteins was 48.3 mg/g. The target proteins were separated with high purity and separation efficiency up to 96.6%. Their specificity and enrichment ability were maintained during six cycles of adsorption–elution operations. The advantages of this novel nanoparticle can open a window for the multifunction of nanomaterials and their biological application.