Doxycycline Release and Antibacterial Activity From PMMA/PEO Electrospun Nanofibers

Objectives: To investigate the use of polymethyl methacrylate (PMMA) electrospun nanofibers containing different amounts of polyethylene oxide (PEO) as a doxycycline delivery system and test their antibacterial activity against oral pathogens.
Methods: PMMA powders with different molecular weights (Mw ~75,000 and Mw~996,000, Sigma-Aldrich) were dissolved in N, N-dimethylformamide (DMF). PEO (Mw ~200,000, Sigma-Aldrich) was added to the PMMA-DMF solution according to the concentration determined for each group (0%, 10%, 20% or 30%). The final polymer concentration was 15% (w/v). 2% Doxycycline monohydrate (DOX) was added to the solutions and submitted to vortex mixing for 1 min at 3000 rpm. The solution was transferred to a plastic syringe and fit into a Nanofiber Electrospinning Unit (NEU – Kato Tech, Japan). The parameters applied were: voltage at 17.2kV; the distance between the needle tip and the collector plate 20cm; target speed at 2m/min; and transverse speed at 1cm/min. Syringe pump speed was 0.15mm/min. DOX release was determined by RP-HPLC from 0.7mL aliquots of the PBS media containing 10 mg of fiber mats for up to 120 h. Antibacterial activity was tested against S.Mutans and E.feacalis from inhibition halos. The experiments were performed in triplicate. All comparisons were done with ANOVA, α=5%.

Results: The addition of PEO to the PMMA fibers did not affect the fibers appearance and diameter. Increases in the %PEO resulted in higher doxycycline release during the first 24h. The fibers containing 30% PEO showed statistically significant higher release when compared to the other groups at all times. The doxycycline released from the fibers containing 20% or 30% of PEO showed to be effective against S.mutans, but not against E. feacalis.
Conclusions: PMMA-PEO nanofibers were effectively produced by electrospinning. Higher concentrations of PEO resulted in increased release of DOX and more effective antibacterial action against S.mutans.