Development of boron doped tissue scaffolds which have synergistic effects with beta-lactame antibiotics

In the presented study, it was aimed to develop boron-doped hydroxyapatite (B-HAp)/chitosan tissue scaffolds which have synergistic effect with beta-lactame antibiotics as systems to prevent infection and speed up the treatment of any bone damage. For this purpose, cell proliferation was investigated by cell culture studies with MC3T3-E1 mouse precursor bone cell line. In addition, the synergistic effect between amoxicillin (AMX), a beta-lactam antibiotic, and B-HAp, produced by the biomimetic method, was studied with selected bacterial strains. AMX loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles were produced using the double-emulsion preparation-solvent evaporation (w/o/w) method. Encapsulation yield of AMX to PLGA nanoparticles was found to be 36%. The diameters of empty and AMX loaded PLGA nanoparticles were determined to be 187 nm and 182 nm, respectively. It has been proven through the 85-day release study with PLGA nanoparticles that 20% of AMX is released by a burst effect in the first hour and the AMX release is carried out in a long-term and controlled manner, proving that the release is achieved by the diffusion mechanism according to the "Higuchi model". In the on-going study B-HAp/chitosan nanocomposite tissue scaffolds were prepared by freeze-drying method in the presence of AMX loaded PLGA nanoparticles and their characteristics were determined. It has been observed that the AMX release is achieved by a slower and more controlled diffusion mechanism than that of the particles. In-vitro cell culture studies were performed with the MC3T3-E1 cell line for 7-day to examine the effect of AMX loaded PLGA nanoparticle containing B-HAp/chitosan tissue scaffolds on cell proliferation. There was no statistically significant effect of low AMX doses used with B-HAp on cell proliferation. Four different bacterial strains (Staphylococcus aureus ATCC®25923, Escherichia coli ATCC®25922, Klebsiella pneumoniae ATCC®BAA-1144 and Klebsiella pneumoniae ATCC®700603), which produce the beta-lactamase enzyme, and three different methods (double disk synergy method, agar diffusion method and gradient test) were used to examine the synergistic effect between the beta-lactame antibiotic, AMX, and B-HAp. Test results proved the synergistic effect between AMX and B-HAp. The results obtained within the scope of the study indicated that beta-lactam antibiotic releasing and boron containing tissue scaffolds could be used effectively with their cellular and antibacterial properties in bone tissue regeneration.