Insights into the production and versatile agricultural applications of nanochitin for sustainable circularity: a review

Chitin exhibits remarkable biocompatibility and biodegradability; nonetheless, its potential remains largely unexplored due to its hydrophobic nature, which makes it insoluble in water. Industrial marine food wastes, including crustacean shells, are the most plentiful and the potential source of chitin. High-performance chitin nanoparticles have been developed by understanding their biological characteristics and advanced preparation methods. The creation of nano-chitin materials is a significant topic due to its distinct dimensional, optical, mechanical, and other properties i.e. high surface area, low density and high dispersibility. Chitin nanocrystals and nanofibers could be fabricated by depolymerizing and demineralizing crustacean shell waste following various top-down and bottom-up methods, viz. acid hydrolysis, deep eutectic hydrolysis, TEMPO-mediated oxidation, self-assembly, etc. Morphology of the nanochitin and applications pertaining to respective nano-fibrillation have been tabulated using the aforementioned methods. The present review summarizes the significant current developments in the synthesis of chitin nanoforms, i.e., nanochitin, nanofiber, or nanocrystal, along with their impact on enhancing plant growth and quality. Nanochitin could be utilized as fertilizers, biostimulant, plant elicitor, biocide as well as for seed treatment and appeared as an organic substitute for sustainable agricultural practices.