Preparation and characterization of silk fibroin/chitosan composite sponges for tissue engineering

In this study, three-dimensional silk fibroin/chitosan (SF/CTS) composite sponges were successfully prepared with an interconnected porous structure and proper mechanical properties. Silk fibroin and chitosan have the potential to mimic a natural extra-cellular matrix (ECM). For the sponge preparation, silk fibroin from the Bombyx mori silkworm and chitosan were used, in different proportions, as composites. Sponges were prepared by means of freezing and lyophylization of corresponding composite solutions. The properties of composite sponges, such as the microstructure as well as the chemical and physical properties were studied. In the present investigation, silk fibroin, chitosan and their mixtures were characterized by attenuated total reflection Fourier transform infra-red spectroscopy (ATR-FTIR), swelling properties, thermogravimetric analysis and scanning electron microscopy (SEM). The ATR-FTIR analysis indicated a shift of band corresponding to CO, CN, COC. Moreover, NH groups of SF and CO and NH2 groups of chitosan might have participated in a specific intermolecular interaction among themselves. Thermogravimetric results suggested a higher temperature of decomposition for SF/CTS sponges than sponges made of pure silk fibroin or chitosan. Scanning electron microscopy observations showed the sponges of SF/CTS with pore size from 20 to 150 μm, which is appropriate for cell growth. Biocompatibility of sponges was confirmed by in vitro test. SF/CTS sponges have sufficient mechanical integrity to resist handling during implantation and in vivo loading. Both the compressive modulus and compressive strength for the sponge decrease with the increase of silk fibroin content in the sponge. Sponges made of silk fibroin/chitosan mixtures can be interesting materials for tissue engineering as scaffold for temporary supporting the formation of new tissue and organs.