Figure 1.

(a) Timeline of discovery, analysis, extraction, use, and future direction of chitin and nanochitin. Red and purple dashed frames indicate chitin nanocrystal and nanofiber, respectively. Adapted with permission from ref (19). Copyright 2018 Elsevier. Summary of publications relating to (b) chitin, nanochitin, and nanocellulose and (c) comparison of chitin nanofibers and nanocrystals. The number of publications was collected from the Science and Engineering Indicators of the National Science Foundation between 2000 and 2020 using Scopus. The research was limited to titles, abstracts, and keywords as follows: chitin/cellulose (*) nanocrystal and nanofiber, including * nanowhisker, * whisker, * nanorod, * crystallite, nanocrystalline *, * nanofiber, * nanofibril, nanofibrillar *, and nanofibrillated *.