Contents lists available at ScienceDirect Materials Science & Engineering C journal homepage: www.elsevier.com/locate/msec Ultrasound assisted reverse micelle efficient synthesis of new Ta-MOF@ Fe 3 O 4 core/shell nanostructures as a novel candidate for lipase immobilization Ghasem Sargazi a , Daryoush Afzali b, ⁎ , Ahmad Khajeh Ebrahimi c , Arastoo Badoei-dalfard d , Saeid Malekabadi d , Zahra Karami d a Department of Nanotechnology Engineering, Mineral Industries Research Center, Shahid Bahonar University of Kerman, Kerman, Iran b Department of Nanotechnology, Graduate University of Advanced Technology, Kerman, Iran c School of chemistry, College of science, University of Tehran, Tehran, Iran d Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran ARTICLE INFO Keywords: Ta-MOF@ Fe 3 O 4 Core/shell nanostructure UARM method Enzyme immobilization Bacillus licheniformis Km12 lipase ABSTRACT In the present study, Ta-MOF@Fe 3 O 4 core/shell nanostructures were synthesized in optimal conditions using the rapid, efficient, and novel ultrasound assisted reverse micelle method. FTIR, TGA/DTG, XRD, TEM, EDS and N 2 adsorption/desorption isotherms were conducted in order to obtain samples with desirable properties. Results showed that the synthesized products had the thermal stability of 200 °C, particle-size distribution of 38 nm and surface area of 740 m 2 /g. Also, the VSM test showed that these compounds have desirable magnetic properties which provide the opportunity for recovery. Based on these obtained properties, final products were used as a novel candidate for enzyme immobilization. Results of SEM images revealed that the Bacillus licheniformis Km12 lipase is efficiently loaded on the Ta-MOF@Fe 3 O 4 core/shell substrate. The stability test indicated the high stability of the enzyme loaded into these nanostructures. The synthesis method and the results obtained from enzyme immobilization developed in this study can be a new strategy for various applications of these novel compounds in diverse biological fields. 1. Introduction Lipase (triacylglycerol ester hydrolase, EC 3.1.1.3) has many in- dustrial applications, because its catalyzes hydrolysis of triacylglycerol into glycerol and fatty acids [1]. In organic systems, the enzyme cata- lyzes the reverse synthesis reaction to produce esters [2,3]. Recently, the use of lipase as a catalyst to produce biodiesel by transforming triglycerides into fatty acid alkyl esters has been reported [4]. However, the free lipase is not favored in industrial developments because it is difficult to recover for reuse, and it has low stability. These drawbacks can be overcome by immobilization on various supports. Several methods have been reported for the immobilization of lipases on dif- ferent supports [5] either by covalent binding [6], entrapment [7], or adsorption [8]. Magnetic microparticles/nanoparticles are also used to immobilize lipase by our group and other groups in the world [6,9]. The properties of supporting materials and the method of immobiliza- tion affect activity of immobilized lipase [10–12]. In recent years, nanostructured materials have been used as supports for enzyme immobilization, since nanoparticles due to the high surface area: volume ratios can effectively improve the enzyme loading and the catalytic efficiency of the immobilized enzyme [13]. One of these nanostructures is nanocrystalline metal-organic frame- work (NMOF) referring to a class of coordination polymers consisted of various metals and linkers [14,15], which are applicable for a variety of fields, including separation [16], gas sorption [17], drug delivery [18,19], and as well as biological applications such as enzyme stabili- zation [20] due to their structural flexibility in addition to desirable physicochemical properties [21]. In our previous study, the Ta-MOF nanostructures were successfully synthesized [22], and distinctive properties in adsorption fields compared to other samples were de- monstrated [23–25]. Compared to pure MOFs, the use of MOF@core/shell nanostructures has been increased regarded due to its improved physicochemical properties resulting from integration with single component [18,26,27]. Such advantages have made these compounds as a novel candidate with practical potential in various fields of engineering [28] https://doi.org/10.1016/j.msec.2018.08.041 Received 22 March 2018; Received in revised form 15 July 2018; Accepted 19 August 2018 ⁎ Corresponding author. E-mail address: darush_afzali@yahoo.com (D. Afzali). Materials Science & Engineering C 93 (2018) 768–775 Available online 20 August 2018 0928-4931/ © 2018 Elsevier B.V. All rights reserved. T