Preparation of magnetic porous terpolymer and its application in cellulase immobilization

Abstract

In this work, a series of porous terpolymers with degrees of crosslinking at 30–65% were synthesized by suspension polymerization. Fe3O4 nanoparticles were used to modify the porous terpolymer with degree of crosslinking at 30%. The resulting terpolymers with mean pore size of 10–30 nm were used as supports for immobilization of cellulases through covalent bondings. The Fourier transform infrared spectroscopy and thermal gravity analysis measurements demonstrated that cellulases were immobilized onto the porous terpolymers. The effects of pH and temperature on enzyme activity were investigated in acetate buffer medium by hydrolysis of sodium carboxymethyl celluloses. The reusability of immobilized cellulases was also investigated. The result showed that immobilized cellulases exhibited higher residual activities and enzyme activities than free cellulases in wide ranges of pH and temperature. We also found that the reusability of cellulases immobilized on terpolymers with magnetism was better than that of cellulases immobilized on terpolymers without magnetism. POLYM. ENG. SCI., 55:1039–1045, 2015. © 2014 Society of Plastics Engineers

Immobilization of cellulase on a silica gel substrate modified using a 3-APTES self-assembled monolayer

“…The relative activity of the immobilized cellulase retained 100–82 % initial activity from 1st to 7th cycle, 60–48 % from 8th to 13th cycle, and 36–23 % from 14th to 26th, respectively. In comparison, the immobilized cellulase was applied to hydrolyze CMC solution 3 h for each cycle, which is longer than previously reported (Mubarak et al 2014 ; Mishra and Sardar 2015 ; Wang et al 2015 ; Qi et al 2015 ; Anuradha Jabasingh and Valli Nachiyar 2011 ; Abraham et al 2014 ; Gokhale et al 2013 ; Verma et al 2013 ). The immobilized cellulase exhibits remarkable reusability up to 13 recycles.…”

“…Because free cellulase is more active than immobilized cellulase, a small amount of cellulase leaked (desorbed) would result in a high enzyme activity. Linear enzyme activity loss of immobilized cellulase was observed according to number of recycles in many prior studies, which suggests leaked (desorbed) cellulase strongly contributed to the activity and the lack of reusability of immobilized cellulase (Mubarak et al 2014 ; Wang et al 2015 ; Qi et al 2015 ; Ungurean et al 2013 ). In order to test the enzyme leak (desorption) of immobilized cellulase during hydrolysis of CMC, the immobilized cellulase was centrifuged from the CMC solution after 6 h and then the reactor was kept running.…”

“…The initial concentration of cellulase solution for immobilization of silica gel was 17.5 mg/ml (5× diluted). The highest activities of free and immobilized cellulase were considered as control groups for each series of experiments, respectively, and defined 100 % relative activity (Qi et al 2015 ).…”

“…The typical specific activity of immobilized cellulase by covalent binding is below 52 % (Li et al 2007 , 2013 ; Wang et al 2015 ). However, the stable covalent binding also leads to very high reusability of immobilized cellulase (Wang et al 2015 ; Li et al 2013 ; Qi et al 2015 ; Zang et al 2014 ). This major advantage make covalent binding very promising in industrial applications.…”

“…Researchers applied many kinds of materials as carriers for immobilization of cellulase, such as nano-silver and gold particle (Mishra and Sardar 2015 ), functionalized multiwall carbon nanotubes (Mubarak et al 2014 ), copolymers (Tata et al 2015 ), silicate clay minerals (Safari Sinegani et al 2005 ), modified Chitosan Beads (Dinçer and Telefoncu 2007 ), modified activated carbon (Anuradha Jabasingh and Valli Nachiyar 2011 ). Recently, Fe 3 O 4 magnetic nanoparticle have been paid much attention by researchers for immobilization of cellulase, due to its easy separation from the hydrolysis solution when applying magnetic field (Xu et al 2011 ; Zhang et al 2015 ; Li et al 2013 ; Qi et al 2015 ; Zang et al 2014 ). Unfortunately, the preferred pH condition for immobilized cellulase is slightly acidic (5) dissolving the Fe 3 O 4 back to Fe 2+ and Fe 3+ .…”