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Although fused deposition modeling (FDM) has made it possible to create reproducible three-dimensional poly(lactic acid) (PLA) scaffolds, their efficacy for tissue engineering applications is limited by their lack of osteoinductive properties and antibacterial functions. Building on the success of the FDM constructs capable of supporting bone regeneration, we report here on the development of PLA scaffolds infused with sodium alginate cross-linked with both calcium and zinc divalent cations. Zn 2+ cations were used to confer antibacterial and osteoinductive properties to enhance the performance of nontoxic PLA-alginate. Both the PLA and alginate polymers have been approved by the US Food and Drug Administration. In vivo bone regeneration capacity was demonstrated on a rabbit model by tomography and histological analysis. The scaffolds exhibited antibacterial activity against Gram-positive methicillin-resistant Staphylococcus epidermidis and Gram-negative Pseudomonas aeruginosa , while the control scaffolds could not resist the two microbial species tested. The scaffolds' physical properties were evaluated by field emission scanning electron microscopy with energy-disperse X-ray spectroscopy, Fourier transform infrared spectroscopy, water absorption, porosity measurements, and compression tests in dry and swollen states at body temperature. Their superior compressive properties, water uptake, and osteoinductive and antibacterial activities thus make them promising candidates for bone tissue regeneration.

Alginates are renewable materials with excellent biocompatibility and cost-effectiveness in comparison with other biodegradable polymers. However, these hydrogels have poor mechanical properties that restrict their applications in biomedical fields such as skin tissue engineering. In this regard, the study follows an enhanced engineering route to produce alginate-based films reinforced with different amounts (0, 0.1, 0.5, 1 and 2% w/w) of carbon nanofibers (CNFs) and characterize their physical and biological properties. The results of this study showed that these composites possess similar biological properties to neat alginate hydrogels. Thus, none of the synthesized composite materials were cytotoxic and no cell adhesion was observed on the films. Water sorption at the body temperature did not suffer strong changes with the incorporation of CNFs into the alginate matrix. The dynamic mechanical and tensile/compressive properties of calcium alginate significantly improved with the addition of even a very low amount of CNFs. Thus, the tensile and compression modulus of the calcium alginate films in the dry and hydrated state increases up to three and six times, respectively, with the addition of 2% w/w CNFs. In addition, the composites reinforced with the lowest CNFs content have the advantage of possessing more transparency and lower production costs., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)