Cellulose nanofibers and composites: An insight into basics and biomedical applications

Abstract

Cellulose nanofibers (CNFs) are a type of nanocomposites of the polysaccharide cellulose. CNFs are obtained by the mechanical treatment of the pre-treated cellulosic extract. The mechanical treatment processes include methods like high pressure homogenization, micro fluidization, cryocrushing, grinding, high intensity ultrasonication and electrospinning. CNFs exist in different forms like suspensions, powders, films, hydrogels and aerogels. CNFs are also subjected to various surface modifications like acetylation/esterification, silylation, TEMPO oxidation, etc. This led to an enhancement in properties of CNFs. Such modifications e.g. TEMPO oxidation of CNFs have imparted variety of excellent biomedical applications. CNFs in different forms (especially aerogels and hydrogels) and CNF composites have been studied for various biomedical applications including drug delivery, wound healing, tissue engineering, protein delivery, antibacterial activity and biosensor application. This review article discusses the sources, isolation, fabrication and recent developments in biomedical applications of CNFs.