Electrospun PCL Mats Modified with Magnetic Nanoparticles and Tannic Acid with Antibacterial and Possible Antiosteosarcoma Activity for Bone Tissue Engineering and Cancer Treatment

Modifying scaffolds with agents that at the same time positively influence osteogenic cells and have a negative impact on cancerous growth, is a promising solution for patients with bone tissue defects following tumor excision. Such materials may not only boost tissue regeneration but also limit the risk of cancer reoccurrence. In our study, we developed novel bifunctional scaffolds containing magnetic nanoparticles grafted with PCL (MNP@PCL) and tannic acid (TA), which may be directed to support normal bone cells and suppress osteosarcoma cells. First, MNPs were postsynthetically surface-modified, by grafting poly(ε-caprolactone) (PCL) from the surface via ring opening polymerization of ε-caprolactone, to provide their uniform distribution within the polymer matrix. Then, fiber mats containing a fixed amount of MNPs (2 wt %) and increasing content of TA (0, 1, 5, and 10 wt %) were prepared by electrospinning method. Both MNP@PCL and TA decreased polymer crystallinity. The interaction between the MNPs and TA significantly influenced the mat morphology, thermal properties, and initial hydrolytic performance. The most intensive TA release was observed mainly within first 6 h of incubation, and it was 3.5-fold higher (ca. 0.02 mg of TA/per mg of mat) for mfPCL@TA-10 compared to mfPCL@TA-5. Moreover, TA-containing magnetic mats suppressed the metabolic activity of osteosarcoma cells. They also demonstrated enhanced antimicrobial properties against the bacteria typically accompanying orthopedic complications, reducing the population of Gram-positive bacteria by more than 90% compared to the neat PCL mat. This proves the high potential of these materials for combining cancer treatment with bone tissue engineering.