Novel non-cytotoxic alginate–lignin hybrid aerogels as scaffolds for tissue engineering

Abstract

This paper presents a novel approach towards the production of hybrid alginate-lignin aerogels. The key idea of the approach is to employ pressurized carbon dioxide for gelation. Exposure of alginate and lignin solution containing calcium carbonate to CO2 at 4.5 MPa resulted in a hydrogel formation. Various lignin and CaCO3 concentrations were studied. Stable hydrogels can be formed up to 2:1 (w/w) alginate-to-lignin ratio. Upon substitution of water with ethanol, gels were dried in supercritical CO2 to produce aerogels. Aerogels were characterized in terms of bulk density, specific surface area and pore volume. To introduce macroporosity, the CO2 induced gelation was supplemented with rapid depressurization (foaming process). Porosity, mean pore size and interconnectivity in the macroporous range were assessed by micro-CT. Youngâ s modulus of alginate-lignin aerogels was measured in both dry and wet state. Cell studies revealed that alginate-lignin aerogels are non-cytotoxic and demonstrate good cell adhesion properties making them attractive candidates for a wide range of applications including tissue engineering and regenerative medicine.