New Techniques for Optimization of Surface Area and Porosity in Nanochitins and Nanochitosans

This chapter outlines the beneficial activities of chitosan and then describes the earliest observations of the expanded structure of isolated chitosans from filamentous fungi, most notably cultivated Absidia coerulea. Fungal chitin-glucan complexes are currently being evaluated in animal models of atherosclerosis and obesity. Impressive advances in the reactivity of chitins and chitosans of various origins have been made possible by the isolation of nanofibrils with surface area as high as 700 m(2)/g by mechanically disassembling the structures occurring in vivo. These procedures lend themselves to easy scaling-up, in contrast to electrospinning that moreover often involves the use of dangerous solvents. By drying chitosan preparations with the aid of supercritical CO2, aerogels with surface area of 50-750 m(2)/g are obtained, and can be easily crosslinked with genipin in order to optimize the average pore size for the preparation of scaffolds of interest in orthopedics.