Tailoring a robust nanozyme formulation based on surfactant stabilized lipase immobilized onto newly fabricated magnetic silica anchored graphene nanocomposite: Aggrandized stability and application

Abstract

Candida rugosa lipase (CRL) was treated with surfactants and immobilized onto the novel formulated magnetic graphene anchored silica nanocomposite (Fe₃O₄/SiO₂/Gr NC). For this purpose, the surface of lipase was initially coated with Triton-X 100 and cetyltrimethylammonium bromide surfactants, to stabilize enzyme in its open form and was then adsorbed onto aminated Fe₃O₄/SiO₂/Gr NC. Glutaraldehyde (GA) was then utilized to cross-link the adsorbed lipase onto the NC. The fabricated NC and conjugated lipase was characterized by various techniques such as FT-IR, XRD, TGA, SEM, TEM, CLSM, CD and Fluorescence spectroscopy. The magnetic character of the as-synthesized NC was verified by AGM investigation. CD and fluorescence spectroscopic analysis demonstrated slight structural rearrangements in lipase upon conjugation. The surfactant stabilized immobilized lipase demonstrated significantly enhanced thermostability, tolerance to various metal ions and inhibitors. The immobilization yield obtained owing to lipase interfacial activation by Triton X 100 and CTAB was remarkably enhanced by 6-folds and 3-folds, respectively which were remarkably higher in comparison to free immobilized lipase. The fabricated nanobiocatalysts were employed to synthesise green apple flavour ester, ethyl valerate via esterification reaction. Triton X 100 stabilized immobilized lipase was a better performer in yielding green apple flavour ester, demonstrating about 90% ester yield as compared to 78% yield obtained by CTAB stabilized immobilized lipase preparation. The obtained outcomes suggested that enzyme structure was stabilized by the GA treatment if executed in the absence or in the presence of detergent, and that, in the company of detergent, a conformation of the lipase with the exposed active center to the medium provided an aggrandized catalytic performance.

Keywords: Enzymatic flavour synthesis; Lipase; Magnetic graphene anchored silica nanocomposite; Nanobiocatalysts; Surfactant stabilized immobilized lipase complex.