Oxidative transformation of dibenzothiophene by chloroperoxidase enzyme immobilized on (1D)-γ-Al2O3 nanorods

• Textural properties of γ-Al2O3 nanorods linked networks were successfully tuned.
• The Al-nR-700 °C resulted highly suitable to perform the chloroperoxidase immobilization.
• A great affinity between the CPO and the nanorods was observed.
• High DBT oxidative biotransformation was revealed.

(1D)-γ-Al2O3 nanorods (Al-nR) were synthesized, thermally treated and characterized by a variety of techniques. This material was used for chloroperoxidase (CPO) enzyme immobilization by physical adsorption and then assayed for the biocatalytic oxidation of dibenzothiophene (DBT). The textural properties of Al-nR nanostructured materials were successfully tuned to perform the CPO immobilization. The nanostructures exhibited a good stability throughout the thermal treatments since its crystallinity remained unchanged and the nanorods arrays were detected in all materials by XRD and HRTEM. A great affinity between the CPO and the nanorods was observed, due to favorable electrostatic interactions during the immobilization process. A remarkable increase on the dibenzothiophene oxidative biotransformation activity of immobilized CPO was obtained when compared with the free CPO. The morphological and textural properties of Al-nR-T material enhanced the enzymatic transformation of dibenzothiophene to form the sulfoxide derivative, especially when the Al-nR-700 °C material was used. The CPO + Al-nR-700 °C preparation exhibited almost twice the activity of the free CPO enzyme. The main product under our experimental conditions was DBT-sulfoxide. The potential application of biocatalytic nanorods for a fuel desulfurization process is discussed.

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