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Objectives and questions: Bone infection (osteomyelitis) is a major complication in orthopaedic surgery and is frequently associated with biofilm formation and antibiotic -resistant strains like methicillin-resistant Staphylococcus aureus (MRSA). While myrrh oil possesses known antibacterial and antioxidant properties, its clinical application is hindered by poor aqueous solubility. This study developed a water-soluble inclusion complex of myrrh oil with hydroxypropyl-β-cyclodextrin (HP-β-CD) and incorporated it into an injectable gelatin methacryloyl (GelMA) hydrogel to create a biocompatible, antibacterial scaffold for localized infection management.

Material and methods: Myrrh oil was extracted via rotary vacuum evaporation and complexed with HP-β-CD to enhance solubility. Antibacterial efficacy of the myrrh–CD complex (0–50% w/v) was evaluated using liquid culture and agar diffusion assays against Escherichia coli, S. aureus, and MRSA. Cytocompatibility was assessed via CCK-8 assays using human-derived stem cells. Antioxidant potential was quantified using the DPPH radical-scavenging assay. Finally, the complex was integrated into a photocrosslinkable GelMA hydrogel (3:1:10 weight ratio) to evaluate the biocompatibility of the 3D formulation.

Results: The myrrh–CD inclusion complex demonstrated significant antibacterial activity at concentrations ≥10% (w/v), achieving >90% reduction in bacterial growth compared to controls (p < 0.01). Agar diffusion assays yielded clear inhibition zones for S. aureus (10.54 mm ± 0.11 mm) and MRSA (10.11 mm ± 0.24 mm). The complex exhibited dose-dependent antioxidant activity, reaching 50% radical scavenging at a concentration of 10% (w/v), while CD alone showed no measurable activity. Cytocompatibility assays confirmed no detectable cytotoxicity, with stem cell viability remaining >90% after 24 hours of exposure to the complex. Furthermore, the GelMA-based 3D hydrogel preserved high cell viability upon direct contact, confirming the maintenance of biocompatibility within the final scaffold formulation.

Discussion and conclusions: Complexation with HP-β-CD successfully solubilizes myrrh oil while preserving its potent antibacterial and antioxidant properties. The resulting myrrh–CD complex shows significant efficacy against resistant strains like MRSA without inducing cytotoxicity in human-derived stem cells. Preliminary incorporation into an injectable GelMA hydrogel maintains high cell viability, supporting its potential as a biocompatible 3D scaffold for the local treatment of bone infections.