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A method for top down preparation of chitosan nanoparticles and nanofibers

Wijesena, Ruchira N., Tissera, Nadeeka, Kannangara, Yasun Y., Lin, Yuan, Amaratunga, Gehan A.J., de Silva, K.M. Nalin
Carbohydrate polymers 2015 v.117 pp. 731-738
atomic force microscopy, chitin, chitosan, crabs, crystal structure, image analysis, nanofibers, nanoparticles, transmission electron microscopy, ultrasonics
A method of top down preparation of chitosan nanoparticles and nanofibers is proposed. Chitin nanofibrils (chitin NFs) were prepared using ultrasonic assisted method from crab shells with an average diameter of 5nm and the length less than 3μm as analyzed by atomic force microscopy and transmission electron microscopy. These chitin nanofibers were used as the precursor material for the preparation of chitosan nanoparticles and nanofibers. The degree of deacetylation of these prepared chitosan nanostructures were found to be approximately 98%. In addition these chitosan nanostructures showed amorphous crystallinity. Transmission electron microscopic studies revealed that chitosan nanoparticles were roughly spherical in nature and had diameters less than 300nm. These larger particles formed through self-assembly of much smaller 25nm particles as evidenced by the TEM imaging. The diameter and the length of the chitosan nanofibers were found to be less than 100nm and 3μm respectively. It is envisaged that due to the cavitation effect, the deacetylated chitin nanofibers were broken down to small pieces to form seed particles. These seed particles can then be self-assembled to form larger chitosan nanoparticles.