Immobilization of catalases on amidoxime polyacrylonitrile nanofibrous membranes

Abstract

Amidoxime polyacrylonitrile (AOPAN) nanofibrous membranes were generated by the reaction between electrospun polyacrylonitrile nanofibrous membranes and hydroxylamine hydrochloride. AOPAN nanofibrous membranes were further modified by Fe(III) chelation for immobilizing catalases with coordination bonds. The surface morphologies of the nanofibrous membranes and immobilized catalases were observed by field emission scanning electron microscopy. Chelation of Fe(III) onto AOPAN nanofibrous membranes was studied by the Langmuir isothermal adsorption model. It was found that the maximum amount of coordinated Fe(III) (qm) was 4.5045 mmol g−1 (dry nanofibrous membranes) and the binding constant (Kl) was 0.0698 L mmol−1. The amounts of immobilized enzymes were determined by the method of Bradford. Kinetic parameters were analyzed for both immobilized and free catalases. The value of Vmax (7122.6 µmol mg−1 min−1) for the immobilized catalases was smaller than that for the free catalases (9203.2 µmol mg−1 min−1), and the Km for the immobilized catalases was larger. The immobilized catalases showed better resistance to pH and temperature change than the free catalases, and the storage stability of immobilized catalases was higher than that of free catalases. As for reusability, the immobilized catalases retained 71% of their activity after eight repeated uses. © 2012 Society of Chemical Industry

Laccase Immobilization by Chelated Metal Ion Coordination Chemistry

“…The laccase immobilized on Fe-AOPAN, Cu-AOPAN and Ni-AOPAN composite nanofibers showed relatively higher storage stability than that of Cd-AOPAN. After being stored for 20 days, the Cu-AOPAN-Lac retained more than 65% of its initial activity, which was higher than the results we previously reported [19].…”

“…Amidoxime polyacrylonitrile (AOPAN) prepared by the chemical modification of the nitrile group was known as good adsorbent for metal ions [18]. Feng [19] has proved that after immobilized onto the surface of Fe(III) chelated AOPAN nanofibrous membrane, catalase showed better stabilities. However, as far as we are concerned, metal ion chelated AOPAN nanofibers have not been used for laccase immobilization yet.…”

Coordination Kinetics of Different Metal Ions with the Amidoximated Polyacrylonitrile Nanofibrous Membranes and Catalytic Behaviors of their Complexes

“…According to the references, PAN solution (16 wt %) was prepared by dissolving appropriate weight of PAN yarns, and then was electrospun under an electrical field with optimized voltage (15 kV), PAN solution feeding rate (1.5 mL/h), and the distance between the needle tip and the collector (10 cm) to obtain PAN nanofibrous membranes (denoted as n ‐PAN). Afterward, the resulting n ‐PAN was amidoximated with the mixture solution of NH 2 OH·HCl (0.4 mol/L) and NaOH (pH regulator) at pH 6 and 70°C for 2 h. The amidoximated n ‐PAN (denoted as AO‐ n ‐PAN) was repeatedly washed with distilled water until washings were neutral and dried under vacuum at 60°C.…”

Surface modification of PAN hollow fiber membrane by chemical reaction

“…It is noteworthy that according to previous reports, the best conditions for the reaction is pH=7 [21]. For this purpose, sodium carbonate was used to adjust the pH of the solution.…”

“…Moreover, this group has shown potential for recovery of heavy metals from wastewater [18,19]. In other words, most of the transition *Corresponding author: m-sadeghi@cc.iut.ac.ir metal ions can form stable complexes with electron-rich compounds and coordinate molecules containing O, N and S, e.g., hydroxyl groups (-OH), amine groups (-NH 2 ) and thiol groups (-SH) [21].…”