Tissue engineering often utilizes polymeric fibers for wound closure or wound healing because nanofibers structurally mimic components found in the extracellular matrix. These scaffolds must mimic the mechanics of the native, healthy tissue and exhibit degradation rates that match regeneration. Electrospinning, which is relatively inexpensive and modular in design, has become the most common way to process fibers. However, this primarily solvent-based process often suffers from variability due to environmental conditions. Previously, we fabricated both poly(caprolactone) (PCL) and poly(lactic acid) (PLA) fiber scaffolds via multilayer coextrusion. This high-throughput method coextrudes two immiscible polymers to form a composite tape, which has rectangular fibers imbedded in a matrix. These rectangular fibers have an inherit surface area increase, compared to the cylindrical fibers obtained from electrospinning.<br/>Currently, this novel processing method is being utilized to fabricate nanofibers for tissue engineering with a range of degradation profiles. Blended PCL/PLA fibers (75/25, 50/50, and 25/75) were fabricated using multilayer coextrusion. Due to the expected immiscibility of the PCL/PLA, the blended fiber morphologies were probed. Discerning the spatial separation between the phases is key to understanding the mechanics and degradation profiles of the blends. Interestingly, the crystallinity of both components was reduced in the extruded blended fibers. Additionally, each fiber blend composition exhibited a reduction in their tensile behavior, which was partially correlated to the reduction in crystallinity. Blended polyester fibers were then submerged in media for 16 weeks. The change in crystallinity of both the PCL and the PLA components was measured as a function of time. It was expected that amorphous domains of the polymer would undergo fragmentation due to hydrolysis, followed by chain scission within the crystalline domains. Differential scanning calorimetry was utilized to understand the chain fragmentation events at each time point, which was then correlated to the change in moduli observed during the early time points. It was determined that blended fibers with a large PCL fraction were ideal for wound healing of more serious injuries that could take several months to heal. However, fibers with majority PLA could be utilized for less severe injuries that require the stability of a scaffold for several hours or a few days.<br/><br/>

Multilayer coextrusion production of tunable bioresorbable polyester fibers for tissue engineering

2019 Fall National Meeting

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