Effect of changing the nanoscale environment on activity and stability of nitrate reductase |
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| Institution: | 1. National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Japan;2. School of Materials and Engineering, Huazhong University of Science and Technology, Wuhan 430074, People''s Republic of China;3. Synchrotron X-ray Station at SPring-8, NIMS, Kouto, Sayo 679-5148, Hyogo, Japan;1. Czech University of Life Sciences Prague, Faculty of Environmental Sciences, Department of Environmental Geosciences, Kamýcká 1176, 165 21 Prague 6 Suchdol, Czech Republic;2. Kocaeli University, Faculty of Science and Arts, Department of Chemistry, 41380 Kocaeli, Turkey;1. Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, 159 Long Pan Road, Nanjing 210037, China;2. College of Chemical Engineering, Nanjing Forestry University, 159 Long Pan Road, Nanjing 210037, China;3. Jiangsu Key Lab for the Chemistry & Utilization of Agricultural and Forest Biomass, 159 Long Pan Road, Nanjing 210037, China;4. Jiangsu Kanion Pharmaceutical Co., Ltd., 58 Haichang South Road, Lianyungang 222001, Jiangsu Province, China |
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| Abstract: | Nitrate reductase (NR) is employed for fabrication of nitrate sensing devices in which the enzyme in immobilized form is used to catalyze the conversion of nitrate to nitrite in the presence of a suitable cofactor. So far, instability of immobilized NR due to the use of inappropriate immobilization matrices has limited the practical applications of these devices. Present study is an attempt to improve the kinetic properties and stability of NR using nanoscale iron oxide (nFe3O4) and zinc oxide (nZnO) particles. The desired nanoparticles were synthesized, surface functionalized, characterized and affixed onto the epoxy resin to yield two nanocomposite supports (epoxy/nFe3O4 and epoxy/nZnO) for immobilizing NR. Epoxy/nFe3O4 and epoxy/nZnO support could load as much as 35.8 ± 0.01 and 33.20 ± 0.01 μg/cm2 of NR with retention of about 93.72 ± 0.50 and 84.81 ± 0.80% of its initial activity respectively. Changes in surface morphology and chemical bonding structure of both the nanocomposite supports after addition of NR were confirmed by scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). Optimum working conditions of pH, temperature and substrate concentration were ascertained for free as well as immobilized NR preparations. Further, storage stability at 4 °C and thermal stability between 25–50 °C were determined for all the NR preparations. Analytical applications of immobilized NR for determination of soil and water nitrates along with reusability data has been included to make sure the usefulness of the procedure. |
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| Keywords: | Nitrate reductase Zinc oxide Iron oxide Nanoparticles Immobilization Nitrate determination |
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