Effect of enzymes characteristics on cellulose nanocrystals yield and properties

Abstract

Cellulose nanocrystal (CNC) is a nanomaterial derived from lignocellulosic mass, with high added value and with a wide range of applications. It is traditionally produced by hydrolysis with concentrated sulfuric acid. However, such severe reaction conditions have environmental and economic consequences for the process. In addition, CNC yield with this method is typically low. Enzymatic hydrolysis , on the other hand, is environmentally friendly and its milder conditions may facilitate control of the CNC characteristics, expanding the possibilities of applying this nanomaterial. This process makes use of a group of hydrolytic enzymes called cellulases, which include three main types: endoglucanases (EGs), witch act in the less organized cellulose regions; exoglucanases, witch act in crystalline cellulose regions; and beta-glucosidases, witch act mainly on the produced cellobiose . Most studies about CNC production by enzymatic hydrolysis use complete cellulases preparations, resulting in the release of CNC with the same or less crystallinity than the original material. In this way, EGs are the enzymes with great potential for CNC production, as they can remove the less organized domains while maintaining the crystalline regions, which are responsible for the unique properties of the nanocrystals. In addition, EGs are classified into various families and have many different properties (like cross-enzyme activities and presence of non-catalytic modules). However, there are no studies that comprehensively studied the effects of these enzyme characteristics on CNC production. Thus, this project aims to understand which EGs characteristics are essential for production of CNC with improved properties, considering that this would open space for the creation of enzymes and enzymatic cocktails specific for this purpose, just like it already does for other applications.