Non-cytotoxic, highly functionalized cellulose nanocrystals with high crystallinity and thermal stability derived from a novel agromass of Elettaria cardamomum, using a soft and benign mild oxalic acid hydrolysis.

Non-cytotoxic, highly crystalline, and functionalized, thermally stable cellulose nanocrystals are extracted from the stems of Elettaria cardamom, a novel underutilised agromass, by employing a neat green, mild oxalic acid hydrolysis. The protocol involves a chemo-mechanical strategy of coupling hydrolysis with steam explosion and homogenization. The obtained CNC showed a crystallinity index of 81.51 %, an aspect ratio of 17.80 ± 1.03 and a high degradation temperature of about 339.07 °C. The extraction procedure imparted a high negative surface functionalization with a zeta potential value of -34.244 ± 0.496 mV and a polydispersity of 16.5 %. The CNC had no antibacterial activity, according to non-cytotoxic experiments conducted on four bacterial strains. This supports the notion of "One Health" in the context of AMR by demonstrating the safety of antibiotic resistance due to consistent exposure upon environmental disposal. The as-extracted nanocellulose crystals can be a potential candidate for commercial application in wide and diversified disciplines like food packaging, anti-infective surfaces for medical devices, biosensors, bioelectronics etc.

A review on the emerging applications of nano-cellulose as advanced coatings.

The unparalleled dependency on petroleum based sources urged the research community to focus on developing renewable products, among which nanocellulose based commodities stands at the zenith due to its abundance, biodegradability and biocompatibility. Nanocellulose in form of coatings, aerogels, hydrogels, films and membranes have its own space in the research platform. The different coating technologies like spray, bar, roller, dip and foam coating are currently employed for the fabrication. The profound surface hydroxyl groups on the cellulose helps to incorporate desired properties like antimicrobial or antioxidant activities, barrier properties, superhydrophobicity or superhydrophilicity as per the applications ranging from biomedical to material engineering. Yet, the chemistry of these coatings have to be precisely tuned for its commercialization since many factors play challenging roles while the fabrication process like adhesion, brittleness and barrier properties. The manuscript discusses these aspects of the nanocellulose based coatings along with its challenges and future perspectives.