Formation of Chitin Nanofibers by Supercritical Antisolvent

Chitin is emerging as a biopolymer of choice because of its potential uses in the numerous biomedical and pharmaceutical applications (e.g., wound dressing, tissue engineering, drug delivery, and antiallergic agent). Nanofibers can provide enhanced properties in many of these applications. Unfortunately, because of the highly crystalline nature, chitin is not soluble in conventional solvents, and it is very difficult to convert it into the fine particulate or fibrous forms. In this work, chitin is dissolved in hexafluoroisopropanol solvent. This solution is then sprayed into supercritical carbon dioxide, which rapidly removes the solvent thus precipitating chitin as nanofibers. On the basis of scanning electron microscopy, precipitated chitin is a web of nanofibers of about 84 nm in diameter. According to the Fourier-transform infrared spectroscopy, chitin molecular structure is preserved during the processing.