Research Article
Semerdzhieva V, Raykova R, Mar
Abstract
Multilayered films of cellulose nanoparticles (NFC’s) and modified multi-walled carbon nanotubes (MWCNT’s) were assembled by means of alternate electrostatic adsorption with positively charged poly(ethyleneimine) (PEI) onto cellulose support. The free carboxylic groups of NFC’s and MWCNT’s were coupled with ethylenediamine. Glucose oxidase and laccase were immobilized by means of Schiff base reaction between aldehyde groups of glutaraldehyde and the free amino sites of the proteins. The immobilized enzymes on the surface of nanoparticles have higher value for the specific activity compared to the enzymes immobilized directly on the cellulose surface indicating the stabilization of the proteins by the nanoparticles. The kinetics of the enzymes, catalyzed reactions and reusability of the enzymes were investigated and were showing better properties for enzymes cross-linked with glutaraldehyde. After 5 days the initial enzyme activity of glucose oxidase was around 85%, but the initial enzyme activity of laccase was 60%. The kinetic investigations of the immobilized enzymes showed no significant difference in Michaelis constant but the maximum reaction rate is decreased.