Sodium alginate/collagen composite multiscale porous scaffolds containing poly(ε-caprolactone) microspheres fabricated based on additive manufacturing technology

Biocompatible porous scaffolds with adjustable pore structures, appropriate mechanical properties and drug loading properties are important components of bone tissue engineering. In this work, biocompatible sodium alginate (SA)/collagen (Col) multiscale porous scaffolds containing poly(epsilon-caprolactone) microspheres (Ms-PCL) have been facilely fabricated based on 3D extrusion printing of the pre-crosslinked composite hydrogels. The prepared composite hydrogels can be 3D extrusion printed into porous scaffolds with different designed shapes and adjustable pore structures. The hydroxyapatite (HAP) nanoparticles have been added into the SA/Col hydrogels to achieve stress dispersion and form double crosslinking networks. SA-Ca2+ crosslinking networks and Col-genipin (GP) crosslinking networks have been constructed to improve the mechanical properties of the scaffolds (about 2557 kPa of compressive stress at 70% strain), and reduce the swelling rate and degradation rate of SA/Col scaffolds. Moreover, the SA/Col hydrogels contain hydrophobic antibacterial drug enrofloxacin loaded Ms-PCL, and in vitro drug release research shows a sustained-release function of porous scaffolds, indicating the potential application of SA/Col porous scaffolds as drug carriers. In addition, the antibacterial experiments show that the composite scaffolds display a distinguished and long-term antibacterial activity against Escherichia coli and Staphylococcus aureus. Furthermore, mouse bone mesenchymal stem cells (mBMSCs) are seeded on the SA/Col composite scaffolds, and an in vitro biocompatibility experiment shows that the mBMSCs can adhere well on the composite scaffolds, which indicate that the fabricated composite scaffolds are biocompatible. In short, all of the above results suggest that the biocompatible SA/Col composite porous scaffolds have enormous application and potential in bone tissue engineering.