Controlled dual drug release by coaxial electrospun fibers - Impact of the core fluid on drug encapsulation and release.

Controlled release of hydrophilic drugs from carriers is still faced with problems due to the poor compatibility of such substances with slowly degradable polymers leading to challenges regarding fabrication as well as undesired burst release of the encapsulated drugs. In this context, coaxial electrospinning being capable of simultaneously using two different solvent systems provides a promising strategy. However, the coaxial electrospinning process is extremely complex and numerous parameters might impact the incorporation as well as release kinetics of the drugs. To address this gap, we fabricated coaxial fibers for controlled co-delivery of two different drugs: bovine serum albumin as a model protein and acyclovir as a small molecule. Controlled release of both embedded drugs was achieved, and drug release profiles could be modulated through modifying spinning techniques as well as compositions and process parameters of the core fluid. Especially, the interactions of the co-incorporated drugs were found to be of key significance for affecting drug distribution within the fibers, and thus ultimately impacting drug release kinetics. Based on our findings, key factors for influencing drug encapsulation and release kinetics from coaxial fibers could be identified, providing a valuable guidance for rational development of coaxial fiber-based drug carriers.