Drug-Delivery Applications of Cellulose Nanofibrils

Cellulose is the most abundant biopolymer with a wide range of applicability in pharmaceutical industry. Cellulose nanofibrils (CNF) could be prepared from native cellulose fibers by extensive hydrolysis of the amorphous form of cellulose. The diameter and width of CNFs range from 2 to 20 nm and 100 to 600 nm respectively. CNFs have also been reported in literature as cellulose nanowhiskers, nanorods, nanofibers, microfibrillated cellulose, or nanofibrillated cellulose. The advantages of CNFs include its nanaoscale dimension, high surface area, unique morphology, low density, and mechanical strength. Moreover, its low cost, easy chemical modification, and availability add to the advantages of CNFs. CNFs have been used as stabilizing agents and pharmaceutical excipients for the development of various drug-delivery systems. These can also be used for controlled release of bioactives. Applications of CNFs as a potential excipient for tableting CNF-based microparticles, films, aerogels/hydrogels, and immobilization of proteins and enzymes on CNF substrates are discussed in this chapter. Toxicological issues are also discussed and summarized.