Carbon Nanotubes as Supports for Inulinase Immobilization

Abstract

Abstract:The commercial inulinase obtained from Aspergillus niger was non-covalently immobilized on multiwalled carbon nanotubes (MWNT-COOH). The immobilization conditions for the carbon nanotubes were defined by the central composite rotational design (CCRD). The effects of enzyme concentration (0.8%-1.7% v/v) and adsorbent:adsorbate ratio (1:460-1:175) on the enzyme immobilization were studied. The adsorbent:adsorbate ratio variable has positive effect and the enzyme concentration has a negative effect on the inulinase immobilization (U/g) response at the 90% significance level. These results show that the lower the enzyme concentration and the higher the adsorbent:adsorbate ratio, better is the immobilization. According to the results, it is possible to observe that the carbon nanotubes present an effective inulinase adsorption. Fast adsorption in about six minutes and a loading capacity of 51,047 U/g support using a 1.3% (v/v) inulinase concentration and a 1:460 adsorbent:adsorbate ratio was observed. The effects of temperature on the immobilized enzyme activity were evaluated, showing better activity at 50 °C. The immobilized enzyme maintained 100% of its activity during five weeks at room temperature. The immobilization strategy with MWNT-COOH was defined by the experimental design, showing that inulinase immobilization is a promising biotechnological application of carbon nanotubes.

Immobilisation of endoinulinase on polyhydroxybutyrate microfibers

“…and immobilised on different carrier materials, when inulobiose (F2) was the main product of inulin hydrolysis, followed by oligosaccharides with the degree of polymerisation = 3. The enzyme loading capacity was comparable with the results of Missau et al (2014), and significantly higher in comparison with the results obtained by other authors (Garlet et al 2014;Karimi et al 2014a, b). …”

“…Several carrier materials have already been examined for endoinulinase immobilisation, such as polystyrene, chitin and chitosan granules, activated alumina, anion-exchange resin (Yun et al 2000), poly-d-lysine coated CaCO 3 micro-particles (Karimi et al 2014b), functionalised silica nanoparticles (Karimi et al 2014a), carbon nanotubes (Garlet et al 2014), or alginate-chitosan beads (Missau et al 2014).…”

Preparation of Nickel Ferrite/Carbon Nanotubes Composite by Microwave Irradiation Technique for Use as Catalyst in Photo-Fenton Reaction

“…It is well known that the use of microwave route for the preparation of powdered catalysts presents as great advantages short synthesis time and production of high surface area particles, being this last characteristic of great importance for catalytic purposes 24,25 . NiFe 2 O 4 is a cubic oxide with a typical inverse spinel structure and has attracted much interest because of its fascinating magnetic and electromagnetic properties 26 , while the MWCNTs have attracted increasing research interest as dye adsorbent 27 , support for enzyme immobilization 28 and catalyst support 29 .…”

Preparation of Zinc Tungstate (ZnWO4) Particles by Solvo-hydrothermal Technique and their Application as Support for Inulinase Immobilization

“…Enzymes are supported in solid matrix for the immobilization by a variety of methods such as physical and chemical mechanisms 12 . The physical adsorption of enzyme 12,14 is entrapment on porous matrix, and in the chemical immobilization enzyme is attachment by covalent bonds 15 and cross-linking between enzyme and matrix 16 . The immobilization by adsorption usually preserves the catalytic activity of the enzyme 17 , therefore, sometimes during its use the immobilized enzyme can be lost when the interactions between adsorbent and enzyme are relatively weak 17,18 , and in this case, the support can be reused.…”