title: Preparation of well-dispersed gold/magnetite nanoparticles embedded on cellulose nanocrystals for efficient immobilization of papain enzyme.
abstract: 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.
authors.affiliation: Qatar Environment and Energy Research Institute (QEERI), Qatar Foundation, Doha, Qatar. kmahmoud@qf.org.qa
authors.forename: Khaled A
authors.initials: KA
authors.lastname: Mahmoud
authors.forename: Edmond
authors.initials: E
authors.lastname: Lam
authors.forename: Sabahudin
authors.initials: S
authors.lastname: Hrapovic
authors.forename: John H T
authors.initials: JH
authors.lastname: Luong
mesh_terms: D001709:Biotechnology / Q000379:methods*; D002482:Cellulose / Q000737:chemistry*; D004563:Electrochemistry; D004789:Enzyme Activation; D004800:Enzymes, Immobilized / Q000737:chemistry* / Q000378:metabolism; D017743:Equipment Reuse; D006046:Gold / Q000737:chemistry; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D010206:Papain / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D013499:Surface Properties; D013696:Temperature
chemical_list: D004800:Enzymes, Immobilized; D058185:Magnetite Nanoparticles; D006046:Gold; D002482:Cellulose; D010206:Papain