Clinoptilolite particles as a carrier for biocatalysts immobilization: invertase immobilization and characterization

Abstract

Clinoptilolite, a natural zeolite, was proposed as a carrier for immobilized biocatalyst systems by polyethyleneimine and glutaraldehyde activation. Invertase (EC 3.2.1.26, beta-fructofuranosidase) as a model biocatalyst was covalently attached onto the particles by direct chemical reaction between aldehyde groups on the particles and amine groups of the enzyme. The effects of polyethyleneimine concentration, activation agent (glutaraldehyde) concentration, pH and invertase concentration on immobilization process were determined. Approximately 7 mg invertase was immobilized on a gram of clinoptilolite particles with 78% retained activity under optimum immobilization conditions. Immobilization did not affect optimum pH of the enzyme, but it brought out a wider pH-activity curve that was accepted as the indication of better pH stability. Immobilization resulted in an increase at the optimum temperature from 55 to 60 C. The K M value of immobilized invertase biosystem was found as approximately 1.5 times higher than that of the free enzyme. Immobilization provided improvement on the thermal stability of invertase, and activity half-life of the immobilized invertase was found as approximately four times longer than that of the free invertase.

Poly(acrylamide/vinylsulfonic acid) hydrogel for invertase immobilization

“…As a result, the optimum pH value changed (Toppare, Erginer, Alkan, & Bakir, 2000). Similar results were found in invertase immobilization studies (Andjelković et al, 2015; Bahar, 2014; Olcer, Ozmen, Sahin, Yilmaz, & Tanriseven, 2013) as well as in our studies (the optimum pH values as 5.5, 4.5, 6.0, 6.0, and 5.5 for composite hydrogels; poly(acrylamide)–sepiolite–invertase, poly(acrylamide/acrylic acid)–sepiolite–invertase, poly(acrylamide/itaconic acid)–sepiolite–invertase, poly(acrylamide/maleic acid)–sepiolite–invertase and for copolymeric hydrogels poly(methacrylamide/maleic acid)–invertase, respectively (Öztop et al, 2009; Öztop et al, 2010; Öztop et al, 2018).…”

Immobilized glucose oxidase biofuel cell anode by MWCNTs, ferrocene, and polyethylenimine: Electrochemical performance

“…Glutaraldehyde solution (0.5 ml, 25% wt/wt) was added on to the prepared electrode, and the cross‐linking reaction was conducted at 25 °C for 30 min. This procedure not only enabled the suitable planting of MWCNTs but also provided active sites for enzyme immobilization . Finally, the electrode was washed with deionized water to remove unreacted cross‐linker and all other unreacted leftover chemicals from previous stages.…”

“…Their comparably small sizes theoretically allow CNTs to be positioned within proximity of the cofactor of the enzymes and reduce the electron tunneling distance . Polyethylenimine (PEI) is one of the useful functional polymers for immobilization and electrochemical applications utilizing different enzymes and GOx . Ferrocene derivatives can easily be incorporated into the PEI structure by using the active amine groups .…”

Stability improvement by crosslinking of previously immobilized glucose oxidaseon carbon nanotube-based bioanode

“…A glutaraldehyde solution (25%, w/w) was employed to crosslink the adsorbed Fc-BPEI for 30 min at 25°C. This procedure enabled not only strong fixing of the MWCNTs on the carbon cloth, but also reactive free aldehyde moieties for the enzyme immobilization [15,18]. The produced electrode was splashed extensively with DI water to eliminate unreacted glutaraldehyde and leftover chemicals from the preceding stages.…”