Pioneering wound care solutions: triaxial wet-spun fibers with bioactive agents for chronic wounds – part I (production and characterization of the triaxial fibers)†

Fiber-based constructs have been produced as an alternative to conventional dressings for the treatment of chronic wounds (CWs), showing good tenability, high surface area and regulable porosity. A commonly used technique for processing such dressings is wet-spinning, which involves precipitating a polymer solution into a coagulation bath containing a non-solvent of that polymer. This process produces fibers with varying diameters and morphologies. In this study, we propose to engineer a triaxial wet-spun fibrous system, consisting of three layers, modified with active agents for wound healing applications. The innermost layer (core) was composed of polycaprolactone (PCL), which imparted the fibers with high elasticity and mechanical properties. This layer was blended with cinnamon leaf oil (CLO), enhancing the system with antibacterial and antioxidant capacities. The intermediate layer contained sodium alginate (SA), conferring a moist environment, loaded with the alanine–alanine–proline–valine (AAPV) tetrapeptide, responsible for regulating the local enzymatic activity. The outermost layer, or shell, was composed of cellulose acetate (CA), which conferred high rigidity and porosity to the fibers. This report represents the initial phase of a broader study, concentrating on the evaluation of the morphological, physical, thermal, and mechanical properties of the proposed triaxial system. The fibers demonstrated maximum elongations at break exceeding 300%, also achieving tenacities up to 41.40 ± 0.03 MPa. They were also found to maintain their structural integrity when exposed to physiological-like conditions, in which the triaxial fibers achieved 9.61 ± 4.08% mass loss after 28 days of incubation, and to exhibit high thermal stability. Furthermore, all fibers attained porosity between 10 and 60% and a dressing composed of these triaxial wet-spun fibers was successfully knitted, serving as proof of concept for the potential application of these fibers in dressing fabrication. The engineered fibers not only possess high mechanical, thermal and structural stability, but also allow for a sustained and orderly release of two active agents, AAPV and CLO, simultaneously controlling local enzymatic activity and reactive oxygen species (ROS) levels and fighting bacterial infections. Overall, the results confirmed the feasibility of the designed wet-spun fibers for future wound healing applications.