Centrifugally spun hybrid polyhydroxyalkanoate/dextran nanocapsule fiber matrix for the delivery of hydrophilic payloads

Biopolymeric micro- and nanofibers with active ingredients have gained significant attention for biological applications. However, the incorporation of hydrophilic compounds into hydrophobic matrices via spinning techniques remain rather unexplored. Here we report the incorporation of dextran nanocapsules (Dex-NCs) in centrifugally spun poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) fibers for the release of hydrophilic payloads. Inverse miniemulsion polymerization was employed to synthesize hydrophilic Dex-NCs with an average size of 0.25 µm. The Dex-NCs were embedded into PHBHHx via dual solvent centrifugal spinning at 0–7 wt% loading, resulting in beaded fibers with average fiber diameters of 4–6 µm. The effect of Dex-NC loading on the melting and crystallization behavior of PHBHHx was limited, while the strength and stiffness of the hybrid fibers was retained. The elongation of the hybrid fiber mats is reduced with increasing Dex-NC loading, but remains suitable for biological applications. Further, the in vitro release measurements showed a time dependent release of embedded Dex-NCs and the payload from the hybrid fibers. We anticipate this hybrid fiber matrix to be a starting point for the development of non-woven mats for slow release of hydrophilic payloads for biological applications, especially for medical wound dressings.