Preparation of chitosan nanofibers and nanoparticlesChitosan nanofibers and nanoparticles were prepared usingdirect ultrasonication of d-chitin NFs dispersion. Before sonica-tion, concentration of the dispersion was adjusted to 0.1% (w/v)in a 100 ml glass beaker. Ultrasonication was carried out usingultrasound tip operating at 24 kHz frequency and 360 W power(UP400S, Hielscher Ultrasound Technology, Germany) for 15 min.Centrifugation technique was utilized for separation of chitosannanoparticles (chitosan NPs) and chitosan nanofibers (chitosanNFs) from water soluble chitosan oligomers. Before centrifugation,the solution was diluted in 9 fold in distilled water. Then the solu-tion was centrifuged at 9000 rpm to separate water soluble chitosanoligomers. Separation of chitosan NPs and chitosan NFs was difficultwith centrifugation technique as resulting dispersion is not sta-ble. However, chitosan NPs could be separated using simple gravityfiltration using ash-less cellulose filter papers (Whatman 42). Fil-trate contained chitosan NPs which are almost free of chitosan NFs.Residue consisted of mostly chitosan NFs and some chitosan NPs