Fotiadou Renia, Chatzikonstantinou Alexandra V, Hammami Mohamed Amen, Chalmpes Nikolaos, Moschovas Dimitrios, Spyrou Konstantinos, Polydera Angeliki C, Avgeropoulos Apostolos, Gournis Dimitrios, Stamatis Haralambos
Biotechnology Laboratory, Department of Biological Applications and Technologies, University of Ioannina, 45110 Ioannina, Greece.
Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA.
Nanomaterials (Basel). 2021 Feb 11;11(2):458. doi: 10.3390/nano11020458.
In this work, hybrid zinc oxide-iron oxide (ZnOFe) magnetic nanoparticles were synthesized employing leaf aqueous extract as a reducing/chelating and capping medium. The resulting magnetic nanoparticles were characterized by basic spectroscopic and microscopic techniques, namely, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared (FTIR) and atomic force microscopy (AFM), exhibiting a spherical shape, average size of 15-17 nm, and a functionalized surface. Lipase from (TLL) was efficiently immobilized on the surface of ZnOFe nanoparticles through physical absorption. The activity of immobilized lipase was found to directly depend on the enzyme to support the mass ratio, and also demonstrated improved pH and temperature activity range compared to free lipase. Furthermore, the novel magnetic nanobiocatalyst (ZnOFe-TLL) was applied to the preparation of hydroxytyrosyl fatty acid esters, including derivatives with omega-3 fatty acids, in non-aqueous media. Conversion yields up to 90% were observed in non-polar solvents, including hydrophobic ionic liquids. Different factors affecting the biocatalyst performance were studied. ZnOFe-TLL was reutilized for eight subsequent cycles, exhibiting 90% remaining esterification activity (720 h of total operation at 50 °C). The green synthesized magnetic nanoparticles, reported here for the first time, are excellent candidates as nanosupports for the immobilization of enzymes with industrial interest, giving rise to nanobiocatalysts with elevated features.
在本研究中，以树叶水提取物作为还原/螯合及封端介质，合成了氧化锌-氧化铁（ZnOFe）复合磁性纳米颗粒。通过基本的光谱和显微镜技术，即X射线衍射（XRD）、X射线光电子能谱（XPS）、傅里叶变换红外光谱（FTIR）和原子力显微镜（AFM）对所得磁性纳米颗粒进行了表征，结果表明其呈球形，平均粒径为15 - 17 nm，且表面功能化。通过物理吸附将来自嗜热栖热放线菌（TLL）的脂肪酶有效地固定在ZnOFe纳米颗粒表面。发现固定化脂肪酶的活性直接取决于酶与载体的质量比，并且与游离脂肪酶相比，其在pH和温度活性范围方面也有所改善。此外，将新型磁性纳米生物催化剂（ZnOFe-TLL）应用于在非水介质中制备羟基酪醇脂肪酸酯，包括ω-3脂肪酸衍生物。在包括疏水性离子液体在内的非极性溶剂中观察到转化率高达90%。研究了影响生物催化剂性能的不同因素。ZnOFe-TLL可重复使用八个连续循环，在50℃下总运行720小时后仍表现出90%的酯化活性。本文首次报道的绿色合成磁性纳米颗粒是用于固定具有工业应用价值的酶的优良纳米载体候选物，可产生具有优异特性的纳米生物催化剂。
