Effect of isolation methods of chitin nanocrystals on the properties of chitin-silver hybrid nanoparticles.

Chitin nanocrystal (ChNC) was isolated using sulfuric acid hydrolysis (ChNCH2SO4), TEMPO-oxidation (ChNCTEMPO), and ammonium persulfate (ChNCAPS) methods, and used for the preparation of hybrid nanoparticles of ChNC/silver nanoparticles (AgNP). The ChNC exhibited a needle-shaped structure with a sulfate group content of 135 μmol/g for ChNCH2SO4 and carboxyl content of 0.71 and 1.42 mmol/g for ChNCTEMPO and ChNCAPS, respectively. ChNC worked as a reducing and stabilizing agent for the production of AgNP and reduced the size of AgNP from 23.9 nm to 6.3 nm in the ChNC/AgNP hybrid. The carboxyl content of ChNC played a significant role for the nucleation, size distribution, and antibacterial activity of ChNC/AgNP. ChNC/AgNP hybrid, especially ChNCAPS/AgNP, exhibited strong antibacterial activity against food-borne pathogenic Gram-negative (E. coli) and Gram-positive (L. monocytogenes) bacteria. The prepared ChNC/AgNP hybrid nanomaterials have a high potential for the application to be used as a nanofiller to improve the properties of food packaging materials to extend the shelf-life of packaged food.