title: A facile and effective immobilization of glucose oxidase on tannic acid modified CoFe2O4 magnetic nanoparticles.
abstract: This article presents a study of glucose oxidase (GOx) immobilization by employing tannic acid (TA) modified-CoFe2O4 (CFO) magnetic nanoparticles which demonstrates novel aspect for enzyme immobilization. By using the strong protein and tannic acid binding, GOx immobilization was carried out via physical adsorption in a simpler way compared with the other immobilization methods which require various chemicals and complicated procedures which is difficult, expensive, time-consuming, and destructive to the enzyme structure. CFO was synthesized by hydrothermal synthesis and modified with TA to immobilize GOx. The immobilized GOx demonstrated maximum catalytic activity at pH 6.5 and 45 °C. The samples were characterized by vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), zeta potential, and fourier transform infrared spectroscopy (FTIR), all of which confirm the surface modification of CFO and GOx immobilization. Also, field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) were performed to demonstrate the surface morphology and chemical structure of samples. According to the Lineweaver-Burk plot, GOx possessed lower affinity to glucose after immobilization, and the Michelis-Menten constant (KM) of immobilized and free GOx were found to be 50.05 mM and 28.00 mM, respectively. The immobilized GOx showed excellent reusability, and even after 8 consecutive activity assay runs, the immobilized GOx maintained ca. 60% of its initial activity.
authors.affiliation: Department of Chemistry, Science & Arts Faculty, Sakarya University, Sakarya 54187, Turkey.
authors.forename: Seher
authors.initials: S
authors.lastname: Altun
authors.affiliation: Biomedical, Magnetic and Semiconductor Materials Research Center (BIMAS-RC), Sakarya University, Sakarya 54187, Turkey.
authors.forename: Bekir
authors.initials: B
authors.lastname: Çakıroğlu
authors.affiliation: School of Pharmacy, Marmara University, Tıbbiye St, 49Haydarpaşa, İstanbul 34688, Turkey.
authors.forename: Münteha
authors.initials: M
authors.lastname: Özacar
authors.affiliation: Department of Chemistry, Science & Arts Faculty, Sakarya University, Sakarya 54187, Turkey; Biomedical, Magnetic and Semiconductor Materials Research Center (BIMAS-RC), Sakarya University, Sakarya 54187, Turkey. Electronic address: mozacar@hotmail.com.
authors.forename: Mahmut
authors.initials: M
authors.lastname: Özacar
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D004800:Enzymes, Immobilized / Q000378:metabolism*; D005290:Ferric Compounds / Q000737:chemistry*; D005949:Glucose Oxidase / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008280:Magnetics; D053758:Nanoparticles; D010087:Oxides / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013634:Tannins / Q000737:chemistry*; D013696:Temperature; D013818:Thermogravimetry; D014961:X-Ray Diffraction
chemical_list: D004800:Enzymes, Immobilized; D005290:Ferric Compounds; D010087:Oxides; D013634:Tannins; C569492:cobalt ferrite; D003035:Cobalt; D005949:Glucose Oxidase
keywords: Cobalt ferrite; Glucose oxidase; Hydrothermal synthesis; Immobilization; Magnetic nanoparticles; Tannic acid