Poly (lactic-co-glycolic acid) (PLGA (92:8)) and a series of PLGA-PEG-PLGA tri block copolymers were synthesized
by direct melt polycondensation. The copolymers were characterized by FTIR, and 1HNMR spectroscopic techniques,
viscosity, gel permeation chromatography (GPC) and powder x-ray diffraction (XRD). The rifampicin (RIF)
loaded polymeric nanospheres (NPs) were prepared by ultrasonication-W/O emulsification technique. The NPs have been
characterized by field emission scanning electron microscopy (FESEM), TEM, powder X-ray diffraction (XRD), UVvisible
spectroscopy and DLS measurements. The drug loaded triblock copolymeric NPs have five folds higher drug content
and drug loading efficiency than that of PLGA microspheres (MPs). The in vitro drug release study shows that the
drug loaded NPs showed an initial burst release after that sustained release up to 72 h. All the triblock copolymeric NPs
follow anomalous drug diffusion mechanism while the PLGA MPs follow non-Fickian super case-II mechanism up to 12
h. The overall in-vitro release follows second order polynomial kinetics up to 72 h. The antimicrobial activity of the RIF
loaded polymer NPs was compared with that of pure RIF and tetracycline (TA). The RIF loaded triblock copolymeric NPs
inhibited the bacterial growth more effectively than the pure RIF and TA.
Keywords: PLGA-PEG-PLGA Triblock copolymers, Rifampicin, In vitro drug release, Korsmeyer-Peppas and Higuchi models,
Antibacterial activity, Polymeric nanospheres.
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