Cellulose has been considered the most abundant biopolymer in nature (Figure It is a linear polysaccharide biopolymer consisting of β-1,4-linked D-glucose units. It can be extracted from several sources, such as trees and cotton. The chemical structure of cellulose shows a large number of hydroxyl (-OH) groups . Cellulose can proceed into the nanoscale, such as nanofibers (CNFs) and nanocrystals (CNCs).