Surface modifications of nanocellulose for drug delivery applications: A critical review

With the development of novel drugs and the discovery of new targets, there is an increased need for novel drug carriers. Nanocellulose has great potential to become a novel drug carrier thanks to its biocompatibility, low toxicity, tunable chemical structure, and sustainability. There are many types of nanocelluloses based on their physical properties (particle size, shape, surface charge), chemical properties (surface functional groups), form (lyophilized, hydrogel, aerogel, membrane) and source (bacterial, animal, plant) and that also largely influences drug release patterns, but also toxicity profile. To our knowledge, so far, no nanocellulose materials have been accepted as ingredients for pharmaceutical formulations. Some types of nanocellulose have however been accepted for use in medical devices, which is also a tightly regulated area. This review focuses on the modification of nanocellulose to enhance its capability as a drug delivery agent and pinpoints the pitfalls for the registration of such novel sustainable material.