Covalent Immobilization of Lipase on Functionalized Magnetic Fe3O4@SiO2 Nanoparticles through Thiol–Ene Click Chemistry for Biofuel Synthesis

Document Type : Research Article

Authors

1 Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran

2 Farzanegan High School, Isfahan Provincial Department of Education, Isfahan, Iran

3 Department of Chemistry, Faculty of Sciences, University of Qom, Qom, Islamic Republic of Iran

Abstract

The development of efficient and recyclable biocatalysts is essential for sustainable biodiesel production. In this work, a magnetically recoverable nanobiocatalyst was prepared through the immobilization of lipase onto vinyl functionalized magnetic silica nanoparticles (Fe3O4@SiO2 V) via a photoinduced thiol–ene click reaction. The immobilization was performed under mild aqueous conditions in phosphate buffer (50 mM, pH 7.5) using 100 mg of Fe3O4@SiO2 V and 25 mg of lipase under UV irradiation (365 nm, 10 W) for 30 min, producing the nanobiocatalyst Fe3O4@SiO2 L. The click based strategy enabled rapid and efficient covalent attachment of the enzyme while preserving catalytic activity. Kinetic analysis revealed that the immobilized enzyme exhibited a slight decrease in catalytic parameters compared with the free enzyme, with V_maxdecreasing from 0.24 to 0.21 mM min⁻¹ and K_mincreasing from 0.35 to 0.52 mM. The turnover number (k_cat) decreased from 168 to 142 min-1, resulting in a catalytic efficiency of 273 mM-1 min-1 for the immobilized system. Notably, the apparent activation energy decreased from 21.0 to 16.0 kJ mol⁻¹ after immobilization, indicating a reduced energetic barrier for catalysis. The catalytic performance of Fe₃O₄@SiO₂ L was evaluated in the esterification of palmitic acid with methanol for biodiesel production, where a maximum conversion of 90.3% was achieved at a palmitic acid:methanol molar ratio of 1:25. Furthermore, the magnetically separable biocatalyst maintained high activity over six consecutive reuse cycles. These results demonstrate that photo mediated thiol–ene click immobilization provides a simple and efficient route for constructing robust magnetic nanobiocatalysts for biodiesel synthesis.

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Advances in Energy and Materials Research

Articles in Press, Accepted Manuscript
Available Online from 28 September 2025

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