Enoxacin-loaded Poly(lactic-co-glycolic acid) Coating on Porous Magnesium Scaffold as a Drug Delivery System: Antibacterial Properties and Inhibition of Osteoclastic Bone Resorption

Implant-associated infection remains a difficult medical problem in orthopedic surgery. Therefore, the development of multifunctional bone implants for treating infection and regenerating lost bone tissue, which may be a result of infection, is important. In the present study, we report the fabrication of enoxacin- loaded poly （lactic-co-glycolic acid） （PLGA） coating on porous magnesium scaffold （Enox-PLGA-Mg） which combine the favorable properties of magnesium, the antibacterial property and the effect of inhibition of osteoclastic bone resorption of enoxacin. The drug loaded PLGA coating of Mg scaffold enables higher drug loading efficiency （52%-56%） than non-coating enoxacin loaded Mg scaffold （Enox-Mg） （4%-5%）. Enox- PLGA-Mg exhibits sustained drug release for more than 14 days, and this controlled release of enoxacin signifcantly inhibits bacterial adhesion and prevented biofilm formation by Staphylococcus epidermidis （ATCC35984） and Staphylococcus aureus （ATCC25923）. Biocompatibility tests with Balb/c mouse embryo fibroblasts （Balb/c 3T3 cells） indicate that PLGA-Mg has better biocompatibility than Mg. Finally, we also demonstrate that Enox-PLCA-Mg extract potently inhibited osteoclast formation in vitro. Therefore, Enox- PLCA-Mg has the potential to be used as a multifunctional controlled drug delivery system bone scaffolds to prevent and/or treat orthopedic peri-implant infections.

Fabrication of Porous Mg-Zn Scaffold through Modified Replica Method for Bone Tissue Engineering

Biodegradable scaffolds are essential parts in hard tissue engineering. A highly porous magnesium-zinc （Mg-Zn 4 wt.%） scaffold with different Mg-Zn powder to liquid media ratios （50 wt.%, 70 wt.% and 90 wt.%） and different concentrations of ethanol （0 vol.%, 10 vol.%, 20 vol.% and 40 vol.%） were prepared through modified replica method. The mechanical properties were assessed through compression test and the structures of scaffolds were examined by Scanning Electron Microscope （SEM）. Results show that, the increase in Mg-Zn powder to liquid media ratio （50 wt.% to 90 wt.%） in ethanol free slurry, increases the thickness of struts （37 lam to 74 lam） and the plateau stress （0.5 MPa to 1.4 MPa）. The results obtained from X-ray Diffractometry （XRD） and compression test indicate that consuming ethanol in liquid media of replica, results in higher plateau stress by 46% due to less Mg-water reaction and no formation of Mg（OH）2 in the scaffold. The results of porosity measurement indicate that water-ethanol mixture composition and different solid fractions have no significant effects on true and apparent porosities of the fabricated scaffolds.