Electrospun composite fibers of PLA/PLGA blends and mesoporous silica nanoparticles for the controlled release of gentamicin sulfate

With the objective of developing a localized gentamicin sulfate (GS) delivery system with a controlled release kinetics for the prevention/management of osteomyelitis, composite electrospun fibers composed of poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) blends and GS loaded mesoporous silica nanoparticles (npSiGS) were prepared (PLA/PLGA: 1:3, 1:1, 3:1 w/w). GS was loaded into silica nanoparticles by adsorption, using a concentrated GS solution, and npSiGS were dispersed in the polymer solutions and immobilized in the polymeric matrix by occlusion, during fibers formations. For comparison, non-composite fibers with the same blend compositions containing GS simply dispersed in the polymeric phase were also produced. GS loaded nanoparticles were characterized by nitrogen adsorption/desorption isotherms and GS loading was quantified by thermogravimetric analysis. The morphology of the electrospun fibers, assessed by SEM, revealed that npSiGS were embedded along the composite fibers, some in the form of small aggregates. In vitro release studies showed that composite fibers exhibited lower initial burst releases and slower release kinetics, dependent on blend composition. Composite fibers with PLGA as the major component (25PLA-npSiGS) had the fastest release kinetics, while fibers with equal amounts of both polymers (50PLA-npSiGS) or with PLGA as the minor component (75PLA-npSiGS) had slower release kinetics, with constant GS release rates after the first day. These results suggest that PLA/PLGA blend composition can be manipulated to obtain composite fibers with a controlled and tailored GS release for at least three weeks. Finally, the antibacterial effect against Staphylococcus aureus of all produced fibers containing GS was confirmed by a disk diffusion method.