Joint treatments of wet-grinding and high-pressure homogenization effectively disassembled chitosan particles into nanofibers by breaking the bond interactions between the chitosan crystalline fibrils using only strong mechanical force. We demonstrated the size reduction of chitosan fibers and characterized the properties and structure of the obtained nanofibrils. Results showed that the obtained nanofibers had a diameter of about 50 nm, which comprised small bundles of nanofibrils with a diameter of 1-5 nm. The zeta potential, viscosity, and stability of the nanofibrous suspension were studied and found to be dependent on the pH value of the aqueous media. Optical properties of the suspension were also characterized. After an isotropic-nematic phase transition, the chitosan nanofibrous colloids exhibited a nematic liquid crystal structure due to the layer-by-layer stacking of self-aligned nanofibers. The freeze-dried liquid crystalline colloids were shaped like a sponge with a wide-range of pore sizes and large surface areas, which could serve as an ideal tissue scaffold. (C) 2010 Elsevier Inc. All rights reserved.