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

Light weight and mechanically strong α-chitin aerogels were fabricated using the sol-gel/self-assembly method from α-chitin in different aqueous alkali hydroxide (KOH, NaOH and LiOH)/urea solutions. All of the α-chitin solutions exhibited temperature-induced rapid gelation behavior. ¹³C nuclear magnetic resonance (NMR) spectra revealed that the aqueous alkali hydroxide/ urea solutions are non-derivatizing solvents for α-chitin. Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and cross-polarization magic angle spinning (CP/MAS) ¹³C NMR confirmed that α-chitin has a stable aggregate structure after undergoing dissolution and regeneration. Subsequently, nanostructured α-chitin aerogels were fabricated by regeneration from the chitin solutions in ethanol and then freeze-drying from t-BuOH. These α-chitin aerogels exhibited high porosity (87% to 94%), low density (0.09 to 0.19 g/cm³), high specific surface area (419 to 535 m²/g) and large pore volume (2.7 to 3.8 cm³/g). Moreover, the α-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 α-chitin aerogels may be useful for various applications, such as catalyst supports, carbon aerogel precursors and biomedical materials.