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

10.22091/jaem.2026.16102.1046

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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