Collagen/cellulose nanofiber hydrogel scaffold: physical, mechanical and cell biocompatibility properties

Collagen hydrogel applications in tissue engineering are limited due to its weak physical and mechanical properties, e.g. loss of water, destruction in the biological medium, weak mechanical properties, and handling difficulty. To improve the physical and mechanical properties of collagen hydrogel, cellulose nanofibers (CNF) were introduced to the collagen hydrogel. Up to 8% CNF, by total dry weight, was added to cold collagen acidic solution and the solution underwent gel formation by increasing pH and temperature to 7.4 and 37 °C, respectively. The gelation time was decreased when CNF was added to the collagen solution. The scanning electron microscopy images of collagen/CNF nanocomposites illustrated porous morphology with larger pore and denser nanofibrous structure than pure collagen. More water retention ability of collagen/CNF hydrogels along with lower hydrolytic degradation rate indicated higher stability of CNF composite hydrogels than pure collagen hydrogel. Mechanical testing demonstrated enhancement in both compression strength and fracture strain when CNF was added to the collagen hydrogel. The presence of free CNF and possible interactions between collagen and CNF was demonstrated by thermogravimetric and Fourier-transform infrared analysis. While the stability and mechanical properties of collagen hydrogel was enhanced by adding CNF, the MTT assay revealed the same cell viability for collagen/CNF scaffold as collagen. Furthermore, the live-dead assay demonstrated excellent capability of CNF nanocomposite for cell 3D culturing.