Light weight, mechanically strong and biocompatible α-chitin aerogels from different aqueous alkali hydroxide/urea solutions

Light weight and mechanically strong alpha-chitin aerogels were fabricated using the sol-gel/self-assembly method from alpha-chitin in different aqueous alkali hydroxide (KOH, NaOH and LiOH)/urea solutions. All of the alpha-chitin solutions exhibited temperature-induced rapid gelation behavior. C-13 nuclear magnetic resonance (NMR) spectra revealed that the aqueous alkali hydroxide/ urea solutions are non-derivatizing solvents for alpha-chitin. Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and cross-polarization magic angle spinning (CP/MAS) C-13 NMR confirmed that alpha-chitin has a stable aggregate structure after undergoing dissolution and regeneration. Subsequently, nanostructured alpha-chitin aerogels were fabricated by regeneration from the chitin solutions in ethanol and then freeze-drying from t-BuOH. These alpha-chitin aerogels exhibited high porosity (87% to 94%), low density (0.09 to 0.19 g/cm(3)), high specific surface area (419 to 535 m(2)/g) and large pore volume (2.7 to 3.8 cm(3)/g). Moreover, the alpha-chitin aerogels exhibited good mechanical properties under compression and tension models. In vitro studies showed that mBMSCs cultured on chitin hydrogels have good biocompatibility. These nanostructured alpha-chitin aerogels may be useful for various applications, such as catalyst supports, carbon aerogel precursors and biomedical materials.