Electrospun ZnO-loaded chitosan/PCL bilayer membranes with spatially designed structure for accelerated wound healing.

A multifunctional bilayer membrane with electrospinning chitosan (CS) and active ZnO nanoparticles was designed. The outer-layer was constructed with ZnO-encapsulated poly(ε-caprolactone) (PCL) ultrafine fibers in a randomly-orientated structure, which could impart the bilayer membrane with great antibacterial activity. The inner-layer was composed with CS fibers with aligned core-shell structure, which could provide anti-inflammatory and effective cell contact guide function. The structure, morphology and crystallization behavior of the bilayer membrane was investigated by FTIR, TEM, SEM and XRD. Importantly, the bi-layered CS/PCL electrospun membrane loading 1.2 wt% ZnO nanoparticles exhibited an enhanced tensile strength and an obvious inhibitory zone against E. coli and S. aureus, and also presented a non-cytotoxic behavior to fibroblasts. Moreover, the as-prepared bi-layered membrane enabled the maintenance of high bioavailability of ZnO nanoparticles and synchronization with the aligned structural feature of CS fibers, which alleviated inflammation, stimulated cellular migration and re-epithelialization in vivo.