Antibacterial Nanofibrous Mats Composed of Eudragit for pH-Dependent Dissolution

A pH-responsive nanofibrous mesh was prepared for the controlled release of antibiotics in response to pH changes. Eudragit EPO (EPO) and Eudragit L100 (L100) were injected through inner and outer needle and simultaneously electrospun through coaxial nozzles composed of inner and outer needles. Various amounts of EPO and L100 were coejected with tetracycline through the needle and simultaneously electrospun to the fibrous meshes. The mass erosion rates of the meshes at pH 6.0 gradually decreased as the amounts of EPO increased, whereas those at pH 2.0 showed negligible differences; these differences were confirmed by scanning electron microscopy and monitoring the dry weight changes. At pH 6.0, the fibrous structures of the meshes rapidly disappeared compared to those under acidic conditions because Eudragit L100 is localized to the shell of the nanofiber during the electrospinning process. Both the pH changes and the blend ratio of the two polymers significantly affected the tetracycline release; tetracycline was rapidly released from the meshes at pH 6.0, whereas the release rates were attenuated at pH 2.0. Tetracycline was released faster from the mesh at higher blend ratios of EPO for both pH values. The electrostatic interaction between EPO and L100 is expected to yield different release profiles of tetracycline. Consequently, higher amounts of encapsulated drugs were released from the mesh at neutral pH and successfully inhibited bacterial growth.