Operational Stability, Regenerability, and Thermodynamics Studies on Biogenic Silica/Magnetite/Graphene Oxide Nanocomposite-Activated Candida rugosa Lipase

• Published in: Polymers Vol. 13; no. 21; p. 3854
• Main Authors: Jacob, Adikwu Gowon, Wahab, Roswanira Abdul, Misson, Mailin
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 08.11.2021; MDPI
• Subjects: Biocatalysts; Biopolymers; Catalytic activity; Chemicals; Enzymes; esterification synthesis; Ethyl valerate; Flame ionization; Fourier transforms; Gas chromatography; Graphene; graphene oxide; Hydrogen atoms; Infrared spectra; Iron oxides; Lipase; Magnetic measurement; Magnetite; nanocomposite; Nanocomposites; Nanoparticles; NMR; Nuclear magnetic resonance; operational stability; Oxidation; Photoelectrons; Potassium; Silicon dioxide; Stability; Thermodynamics; X ray photoelectron spectroscopy; X-ray diffraction; Germany
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym13213854

Inorganic biopolymer-based nanocomposites are useful for stabilizing lipases for enhanced catalytic performance and easy separation. Herein, we report the operational stability, regenerability, and thermodynamics studies of the ternary biogenic silica/magnetite/graphene oxide nanocomposite (SiO2/Fe3O4/GO) as a support for Candida rugosa lipase (CRL). The X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field-electron scanning electron microscopy (FESEM), vibrating sample magnetometry (VSM), and nitrogen adsorption/desorption data on the support and biocatalyst corroborated their successful fabrication. XPS revealed the Fe3O4 adopted Fe2+ and Fe3+ oxidation states, while XRD data of GO yielded a peak at 2θ = 11.67°, with the SiO2/Fe3O4/GO revealing a high surface area (≈261 m2/g). The fourier transform infrared (FTIR) spectra affirmed the successful fabricated supports and catalyst. The half-life and thermodynamic parameters of the superparamagnetic immobilized CRL (CRL/SiO2/Fe3O4/GO) improved over the free CRL. The microwave-regenerated CRL/SiO2/Fe3O4/GO (≈82%) exhibited higher catalytic activity than ultrasonic-regenerated (≈71%) ones. Lower activation (Ea) and higher deactivation energies (Ed) were also noted for the CRL/SiO2/Fe3O4/GO (13.87 kJ/mol, 32.32 kJ/mol) than free CRL (15.26 kJ/mol, 27.60 kJ/mol). A peak at 4.28 min in the gas chromatograph-flame ionization detection (GC-FID) chromatogram of the purified ethyl valerate supported the unique six types of 14 hydrogen atoms of the ester (CAS: 539-82-2) in the proton nuclear magnetic resonance (1H-NMR) data. The results collectively demonstrated the suitability of SiO2/Fe3O4/GO in stabilizing CRL for improved operational stability and thermodynamics and permitted biocatalyst regenerability.