Abstract: BACKGROUND: Due to poor bone blood supply, intravenous antibiotics administration for treating osteomyelitis, it is difficult to achieve effective drug concentration in the focal area of osteomyelitis, poor treatment effect has been clinical bottlenecks. 
OBJECTIVE: To develop a biodegradable biomaterial implant with local sustained release of vancomycin and osteogenic effect, which can promote local bone tissue repair as much as possible while treating osteomyelitis.
METHODS: Vancomycin sodium alginate solutions with concentrations of 6, 12 and 18 g/L were prepared into microspheres by electrospraying; and then the microspheres were vacuum freeze-dried. Poly3-hydroxybutyrate 4-hydroxybutyrate was prepared into electrospinning solution. While electrospinning, vancomycin microspheres were added to the receiving device to wrap them in nanofibers. The electrospinning composites of vancomycin-loaded microspheres with concentrations of 6, 12, and 18 g/L were prepared respectively (denoted as P@VancoMs6, P@VancoMs12, P@VancoMs18). (1) In vitro test: MC3T3-E1 cells were seeded on three kinds of scaffolds, and cell adhesion and proliferation were detected, and the appropriate concentration of vancomycin hydrochloride was screened for subsequent experiments. MC3T3-E1 cells were seeded on P@VancoMs6 and P@VancoMs12, and osteogenic induction medium was added. The in vitro osteogenic properties of the scaffolds were evaluated by immunofluorescence staining of type I collagen and osteocalcin. P@VancoMs6 and P@VancoMs12 were co-cultured with Staphylococcus aureus, respectively, and the antibacterial properties of the complexes were analyzed by the inhibition zone test. (2) The poly-3-hydroxybutyrate 4-hydroxybutyrate scaffolds, P@VancoMs6 and P@VancoMs12 were implanted subcutaneously in SD rats separately, and the biocompatibility of the scaffolds was observed by histological sections.
RESULTS AND CONCLUSION: (1) In vitro experiments: cell adhesion and proliferation experiments showed that P@VancoMs6 and P@VancoMs12 had no effect on cell proliferation and could be used in subsequent experiments. P@VancoMs6 and P@VancoMs12 could inhibit the growth of Staphylococcus aureus, and the inhibitory effect of P@VancoMs12 was more obvious. Immunofluorescence staining showed that P@VancoMs6 and P@VancoMs12 could promote cells to secrete type I collagen and osteocalcin. (2) In vivo experiment: After 4 days of subcutaneous implantation, inflammatory cell infiltration was observed in the three groups of implants, but no necrosis was found. (3) The results showed that the electrospinning scaffolds containing 6 and 12 g/L vancomycin hydrochloride-loaded microspheres played good antibacterial and osteogenic effects.

Key words: electrospinning, biomaterial, scaffold, vancomycin, microsphere, infection, sodium alginate, bone