title: Iron oxide filled magnetic carbon nanotube-enzyme conjugates for recycling of amyloglucosidase: toward useful applications in biofuel production process.
abstract: Biofuels are fast advancing as a new research area to provide alternative sources of sustainable and clean energy. Recent advances in nanotechnology have sought to improve the efficiency of biofuel production, enhancing energy security. In this study, we have incorporated iron oxide nanoparticles into single-walled carbon nanotubes (SWCNTs) to produce magnetic single-walled carbon nanotubes (mSWCNTs). Our objective is to bridge both nanotechnology and biofuel production by immobilizing the enzyme, Amyloglucosidase (AMG), onto mSWCNTs using physical adsorption and covalent immobilization, with the aim of recycling the immobilized enzyme, toward useful applications in biofuel production processes. We have demonstrated that the enzyme retains a certain percentage of its catalytic efficiency (up to 40%) in starch prototype biomass hydrolysis when used repeatedly (up to ten cycles) after immobilization on mSWCNTs, since the nanotubes can be easily separated from the reaction mixture using a simple magnet. The enzyme loading, activity, and structural changes after immobilization onto mSWCNTs were also studied. In addition, we have demonstrated that the immobilized enzyme retains its activity when stored at 4 °C for at least one month. These results, combined with the unique intrinsic properties of the nanotubes, pave the way for greater efficiency in carbon nanotube-enzyme bioreactors and reduced capital costs in industrial enzyme systems.
authors.affiliation: Department of Pharmacy, National University of Singapore, Science Drive 2, S15#05-PI-03, Singapore 117543.
authors.forename: Wei Jiang
authors.initials: WJ
authors.lastname: Goh
authors.forename: Venkata S
authors.initials: VS
authors.lastname: Makam
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
authors.forename: Lifeng
authors.initials: L
authors.lastname: Kang
authors.forename: Minrui
authors.initials: M
authors.lastname: Zheng
authors.forename: Sia Lee
authors.initials: SL
authors.lastname: Yoong
authors.forename: Chammika N B
authors.initials: CN
authors.lastname: Udalagama
authors.forename: Giorgia
authors.initials: G
authors.lastname: Pastorin
mesh_terms: D000327:Adsorption; D001234:Aspergillus niger / Q000737:chemistry / Q000201:enzymology; D056804:Biofuels; D018533:Biomass; D019149:Bioreactors; D002384:Catalysis; D002942:Circular Dichroism; D057075:Enzyme Assays; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry; D005656:Fungal Proteins / Q000737:chemistry*; D005087:Glucan 1,4-alpha-Glucosidase / Q000737:chemistry*; D006868:Hydrolysis; D007700:Kinetics; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D013213:Starch / Q000737:chemistry*
chemical_list: D056804:Biofuels; D004800:Enzymes, Immobilized; D005290:Ferric Compounds; D005656:Fungal Proteins; D058185:Magnetite Nanoparticles; D037742:Nanotubes, Carbon; C000499:ferric oxide; D013213:Starch; D005087:Glucan 1,4-alpha-Glucosidase