Synthesis of polyethylenimine modified Fe₃O₄ nanoparticles with immobilized Cu²⁺ for highly efficient proteins adsorption

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• 作者：Tingting Xia ; Yueping Guan ; Mingzhu Yang ; Wubin Xiong ; Ning Wang ; Shen Zhao ; Chen Guo
• 关键词：Fe3O4&ndash ; PEI NPs ; Protein adsorption ; BHb ; BSA ; Adsorption capacity ; Selectivity
• 刊名：Colloids and Surfaces A: Physicochemical and Engineering Aspects
• 出版年：20 February, 2014
• 年：2014
• 卷：443
• 期：Complete
• 页码：552-559
• 全文大小：1505 K

文摘

We report the modification of amine-functioned Fe₃O₄ nanoparticles (provided by the Laboratory of Bio-Medical Materials of University of Science and Technology Beijing) with polyethylenimine (PEI) using glutaraldehyde (GA) as a linker to increase the concentration of primary amine groups on the surface. The resultant Fe₃O₄-PEI NPs with immobilized iminodiacetic acid (IDA)-Cu²⁺ groups were applied to investigate the adsorption capacity and selectivity of model proteins: bovine hemoglobin (BHb) and bovine serum albumin (BSA). The Fe₃O₄-PEI NPs were characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), particle analyzer, attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), ninhydrin colorimetry and thermogravimetric analysis (TGA). The results showed that the well dispersed Fe₃O₄-PEI NPs had an average size of 172.6 nm and were super-paramagnetic with saturation magnetization of 71.11 emu/g. The characteristic peaks of PEI appeared in the ATR-FTIR spectra of Fe₃O₄-PEI NPs. The study of zeta potential measurement presented that the isoelectric points of the Fe₃O₄-PEI NPs increased to 10.5. Ninhydrin colorimetry analysis of primary amine groups showed that the concentration of primary amine groups on the surface of Fe₃O₄-PEI NPs increased to 0.45 mmol/g and that of TGA is 0.53 mmol/g. These results showed that PEI had been successfully modified on the surface of amine-functioned Fe₃O₄ NPs and the concentration of primary amine groups was significantly increased. The analysis of protein adsorption indicated that the adsorption capacity of BHb was up to about 6000 mg/g and that of BSA was only about 2000 mg/g, which was about one third of that of BHb. The research on the selectivity of protein adsorption was conducted by HPLC. The result showed that the adsorption capacity of BHb was 2.5 times as high as that of BSA, which further proved Fe₃O₄-PEI-Cu²⁺ NPs shows specific adsorption for proteins. These properties suggested the potential of the Fe₃O₄-PEI-Cu²⁺ NPs as protein adsorbent.