Surface functionalization of silica-coated magnetic nanoparticles for covalent attachment of cholesterol oxidase
Surface functionalization of silica-coated magnetic nanoparticles for covalent attachment of cholesterol oxidase
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DOI：
10.1016/j.jmmm.2009.07.075
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发表时间：
2010
影响因子：
2.7
通讯作者：
Franja Šulek;M. Drofenik;M. Habulin;Ž. Knez
中科院分区：
文献类型：
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作者：
Franja Šulek;M. Drofenik;M. Habulin;Ž. Knez
本文系统地介绍了目前用于酶固定化的高功能化硅壳磁性纳米颗粒的制备方法。在苛刻的反应条件下，分别在氨碱性溶液中用热共沉淀法合成了裸磁铁矿(γ-Fe_2O_3)纳米粒子。在严格控制的反应条件下，通过在纳米颗粒表面沉积适当的二氧化硅，成功地实现了磁铁矿纳米颗粒的一次表面工程。其次，通过在颗粒表面包覆有机硅烷，再对颗粒进行戊二醛活化，实现颗粒的二次表面功能化，以增强蛋白质的固定化。随后尝试共价固定化胆固醇氧化酶。利用透射电子显微镜和振动样品磁强计对磁性二氧化硅纳米复合材料的结构和磁性能进行了表征。X-射线衍射测量证实了未包覆的磁铁矿纳米颗粒的尖晶石结构和平均尺寸约为20 nm。扫描电子显微镜-能谱分析表明，硅有一个很强的信号，这意味着二氧化硅在颗粒表面的包覆过程已经成功完成。傅立叶变换红外光谱(FT-IR)分析证实了氨基硅烷分子结合在磁铁矿纳米颗粒表面，形成了Si-O-Si化学键。与游离酶相比，共价结合的胆固醇氧化酶保持了50%的活性。通过戊二醛活化将酶结合到化学修饰的磁性纳米粒子上，是开发生物医学生物传感组件的一种很有前途的方法。
A systematic approach towards the fabrication of highly functionalized silica shell magnetic nanoparticles, presently used for enzyme immobilization, is herein fully presented. The synthesis of bare maghemite (γ-Fe2O3) nanoparticles was accomplished by thermal co-precipitation of iron ions in ammonia alkaline solution at harsh reaction conditions, respectively. Primary surface engineering of maghemite nanoparticles was successfully performed by the proper deposition of silica onto nanoparticles surface under strictly regulated reaction conditions. Next, the secondary surface functionalization of the particles was achieved by coating the particles with organosilane followed by glutaraldehyde activation in order to enhance protein immobilization. Covalent immobilization of cholesterol oxidase was attempted afterwards. The structural and magnetic properties of magnetic silica nanocomposites were characterized by TEM and vibrating sample magnetometer (VSM) instruments. X-ray diffraction measurements confirmed the spinel structure and average size of uncoated maghemite nanoparticles to be around 20nm in diameter. SEM–EDS spectra indicated a strong signal for Si, implying the coating procedure of silica onto the particles surface to be successfully accomplished. Fourier transform infrared (FT-IR) spectra analysis confirmed the binding of amino silane molecules onto the surface of the maghemite nanoparticles mediated Si–O–Si chemical bonds. Compared to the free enzyme, the covalently bound cholesterol oxidase retained 50% of its activity. Binding of enzyme onto chemically modified magnetic nanoparticles via glutaraldehyde activation is a promising method for developing biosensing components in biomedicine.