Production and characterization of pH-sensitive polymeric fibers

Nanofibers with a high surface area/volume ratio, micro-porous structure, high drug loading and encapsulation efficiency, compatibility with different agents, and tunable release profiles demonstrate potential for next-generation drug delivery systems. In colontargeted oral delivery systems, it is necessary to preserve a drug until it reaches the colon during gastrointestinal transit. Various approaches have been employed for colon-specific drug delivery, such as using pH sensitive or enzymatically degradable polymers, prodrugs, and time-controlled systems. Electrospinning is an easy and widely used technique in the production of fiber materials. In the scope of the thesis, fiber meshes in various forms (random and aligned arrangements in nano/micro dimensions) were produced using the electrospinning technique to design a pH-sensitive potential drug delivery system from Eudragit S100 (ES100), a pH-sensitive polymer that dissolves above pH 7.0. In another stage of the thesis, fibers in a core-shell structure were produced in coaxial arrangement using ES100 in the shell part and pectin, a natural polymer that can be enzymatically degraded by various bacteria in the colon microflora, in the core part. Various solvent systems (EtOH, MeOH, MeOH:EtOH, EtOH:DMF, MeOH:DMF, EtOH:DMAc, and MeOH:DMAc) were used in the production of electrospun fiber meshes with different ratios. Electrospinning conditions were optimized for each solution system to produce randomly and aligned fibers with nano/micro-scale diameters. The morphological, chemical, thermal, mechanical, and physical structures of the produced fibers were analyzed, and their biodegradation behaviors were determined. This study reveals that the developed ES100 fibers may have significant potential applications for a colon-targeted drug delivery system.