Electrospun Cellulose Acetate/Polyvinylpyrrolidone Composite Fibers for Tunable Ibuprofen Release: Role of Dissolubility and Condensed Structure

Cellulose acetate (CA) has been widely employed in drug delivery systems for immediate and sustained release of poorly water-soluble drugs. This study aimed to investigate how the solubility and condensed structure of CA based fiber matrices influence the release performance of ibuprofen (IBU). IBU-loaded CA/polyvinylpyrrolidone (PVP) fibers were fabricated via electrospinning with water-soluble PVP as the co-spinning polymer to modulate the fiber solubility. Scanning electron microscopy (SEM) confirmed the preparation of uniform fibers with diameters of 280 nm to 1.550 μm. Fourier transform infrared spectroscopy (FT-IR) revealed the intermolecular interactions between CA and PVP, while FT-IR and X-ray diffraction (XRD) verified the homogeneous dispersion of IBU in an amorphous state within the fibers. Positron annihilation lifetime spectroscopy (PALS) elucidated the effects of annealing temperature on free volume characteristics, demonstrating that higher annealing temperatures reduced free volume size and intensity. In vitro drug release studies demonstrated that IBU release rates increased with higher PVP content due to enhanced dissolution while elevated annealing temperatures slowed release kinetics by reducing free volume fraction. The release kinetics followed first-order behavior with the highest linearity, suggesting the Fickian diffusion release mechanism. These findings highlight the ability to control drug release behavior by tailoring the dissolubility and condensed structure of fiber matrices, offering a promising strategy for optimizing drug delivery systems.