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Preparation of Fe3O4@SiO2@Layered Double Hydroxide Core–Shell Microspheres for Magnetic Separation of Proteins
- Shao, Mingfei, Ning, Fanyu, Zhao, Jingwen, Wei, Min, Evans, David G., Duan, Xue
- Journal of the American Chemical Society 2012 v.134 no.2 pp. 1071-1077
- Escherichia coli, adsorption, binding capacity, biosensors, cations, drugs, green fluorescent protein, histidine, magnetic fields, magnetic separation, magnetite, nickel, recombinant proteins, surface area
- Three-component microspheres containing an SiO₂-coated Fe₃O₄ magnetite core and a layered double hydroxide (LDH) nanoplatelet shell have been synthesized via an in situ growth method. The resulting Fe₃O₄@SiO₂@NiAl-LDH microspheres display three-dimensional core–shell architecture with flowerlike morphology, large surface area (83 m²/g), and uniform mesochannels (4.3 nm). The Ni²⁺ cations in the NiAl-LDH shell provide docking sites for histidine and the materials exhibit excellent performance in the separation of a histidine (His)-tagged green fluorescent protein, with a binding capacity as high as 239 μg/mg. The microspheres show highly selective adsorption of the His-tagged protein from Escherichia coli lysate, demonstrating their practical applicability. Moreover, the microspheres possess superparamagnetism and high saturation magnetization (36.8 emu/g), which allows them to be easily separated from solution by means of an external magnetic field and subsequently reused. The high stability and selectivity of the Fe₃O₄@SiO₂@NiAl-LDH microspheres for the His-tagged protein were retained over several separation cycles. Therefore, this work provides a promising approach for the design and synthesis of multifunctional LDH microspheres, which can be used for the practical purification of recombinant proteins, as well as having other potential applications in a variety of biomedical fields including drug delivery and biosensors.