Obtenção de nanofibrilas de celulose a partir de macroalgas para imobilização enzimática

Abstract

The aim of this study was to produce cellulose nanofibrils from macroalgae for use in enzyme immobilization. The effect of the pre-treatment step on the cellulose isolation was investigated, as well as the relationship between macroalgae mechanical defibrillation and nanofibril size. Furthermore, the relationship between bleaching treatment and crystallinity index of the nanofibrils was investigated, as well as the effect on thermal stability and stability in colloidal suspension. The results showed that the bleaching step promoted the removal of lignocellulosic matrix components, increasing the crystallinity index from 29.5% to 78.3%. In addition, mechanical defibrillation led to the formation of thin nanofibrils (D = 4 nm). Thermal stability of cellulose decreased after bleaching (from 259.2°C to 239.7°C), but the stability of the colloidal suspension increased, as shown by the measurement of the zeta potential, which reduced from -22.4 to -59 mV. The nanofibrils produced were subsequently used in the immobilization phytase, where the effect of pH and ionic strength were evaluated. The biocatalysts produced by immobilization in sodium phosphate buffer at a concentration of 20 mM and pH 6 obtained higher values of immobilization yield (98.9%) and recovered activity (94.8%). The methodology developed herein was efficient in producing cellulose nanofibrils with potential application as particles for enzymatic immobilization.