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Preparation of Well-Dispersed Gold/Magnetite Nanoparticles Embedded on Cellulose Nanocrystals for Efficient Immobilization of Papain Enzyme

2013; American Chemical Society; Volume: 5; Issue: 11 Linguagem: Inglês

10.1021/am4007534

1944-8252

Khaled A. Mahmoud, Edmond Lam, Sabahudin Hrapovic, John H. T. Luong,

Pineapple and bromelain studies

A nanocomposite consisting of magnetite nanoparticles (Fe3O4NPs) and Au nanoparticles (AuNPs) embedded on cellulose nanocrystals (CNCs) was used as a magnetic support for the covalent conjugation of papain and facilitated recovery of this immobilized enzyme. Fe3O4NPs (10–20 nm in diameter) and AuNPs (3–7 nm in diameter) were stable and well-dispersed on the CNC surface. Energy-dispersive spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used to evaluate the surface composition and structure of CNC/Fe3O4NPs/AuNPs. The nanocomposite was successfully used for the immobilization and separation of papain from the reaction mixture. The optimal enzyme loading was 186 mg protein/g CNC/Fe3O4NPs/AuNPs, significantly higher than the value reported in the literature. The activity of immobilized papain was studied by electrochemical detection of its specific binding to the Thc-Fca-Gly-Gly-Tyr-Arg inhibitory sequence bound to an Au electrode. The immobilized enzyme retained 95% of its initial activity after 35 days of storage at 4 °C, compared to 41% for its free form counterpart.