Statement of Purpose: Electrospinning is a facile technique to create fibrous scaffolds that mimic the architecture and size scale of the native extracellular matrix. Recently, we reported on the effect of a stabilizing fiber population in PGLA 90:10 electrospun constructs which improved storage stability and minimized crystallization induced shrinkage of the fabric. By incorporating polymeric fibers with significantly lower glass transition temperature (Tg) we are able to produce high glycolide content electrospun materials that demonstrate maintenance of fiber morphology, areal dimensions, and handling properties by limiting fiber reorganization upon exposure to physiological temperatures. The following demonstrates the temporal properties of both neat PGLA and PDO systems, as well as a thermally stabilized composite system under in vitro conditions.
Methods: Poly(glycolide-co-lactide) (PGLA, 90:10) and poly-dioxanone (PDO) were procured from PURAC and EVONIK, respectively. PGLA and PDO solutions were prepared by dissolution in hexafluoroisopropanol (HFIP) (Dupont) and electrospun on a custom electrospinning apparatus. PGLA and PDO solutions were deposited from an array of separate needles at varying flow rates to generate materials at the following ratios (PGLA:PDO): 2:0, 2:1, 0:2. Electrospun samples were assessed for in vitro performance including mechanics, morphology, shrinkage, and crystallization.
Results: Electrospun materials were fabricated from PGLA, PDO, and a composite system of both. Mechanical testing indicated that the PGLA scaffold maintained tensile strength over seven days in vitro (Figure 1a), but resulted in a reduction in suture pull-out strength and elongation at break (Figures 1b-c). The lower elongation of the fabric can be attributed to the thermally sensitive and amorphous nature of the material. PDO exhibited loss of tensile strength (Figure 1a), but maintenance of suture pull-out strength (Figure 1b), but slight reduction in elongation at break (Figure 1c) after five days in vitro. The composite PGLA:PDO system exhibited intermediate properties between PGLA and PDO resulting in hybrid properties between both systems (Figure 1).
Figure 1a-c: Properties of electrospun fabrics over seven (7) days; a) percent (%) retention of initial tensile strength, b) Percent (%) retention of initial suture pull-out strength c) Percent (%) retention of initial elongation.
Conclusions: We have demonstrated that multiple fiber population electrospun fabrics display hybrid mechanical properties. Incorporation of PDO fibers into PGLA electrospun fabrics resulted in intermediate properties between the two systems while maintaining dimensional stability. Our findings indicate that inclusion of multiple fiber populations can influence the long term mechanical performance producing temporal properties in regards to mechanics, resorption, and potentially biological response.