Emulsion templating of PCL:PGS methacrylate blends for soft tissue engineering

Introduction: Polycaprolactone (PCL) and poly (glycerol sebacate) (PGS) are biodegradable polymers with which high internal phase emulsion (HIPE) templating may be used to create highly porous structures. Although both polymers have been reported for a wide range of hard- and soft-tissue applications, several challenges remain. For example, PCL structures require surface treatment to allow for efficient cell infiltration, which becomes difficult with thick, complex geometries, and PGS is a soft polymer which results in the collapse of its porous structure during necessary processing steps.

Methods: Here, we demonstrate how methacrylated forms of PCL (PCL-M) and PGS (PGS-M) can be blended to create highly tailorable porous structures that support cell growth and overcome the limitations of the two polymers individually. Material properties were characterised via mechanical testing, porous structures were imaged via scanning electron microscopy, and biological properties were investigated by resazurin assay and fluorescent staining.

Results and Discussion: Mechanical testing of bulk blends of PCL-M and PGS-M demonstrated that the polymers mix together uniformly to provide predictable properties at different weight:weight ratios. PolyHIPEs formed of PCL-M and PGS-M were stable and exhibited highly interconnected porosity. Further investigation was undertaken on the 50:50 blend due to its favourable viscosity and rounded porous structure. Adjusting the synthesis parameters of the 50:50 PCL-M:PGS-M blend demonstrated that a wide range of porous structures can be fabricated, with average pore size ranging from 10–69 μm. The blend was demonstrated to be cell compatible, and collagen staining demonstrated that extracellular matrix adhered to the material. Blend-based scaffolds did not require surface treatment to maintain long term cell adhesion, unlike PCL-M-only controls. Overall, this study demonstrated that highly tuneable porous structures for a wide variety of tissue engineering applications can be created by blending PCL-M and PGS-M to form a composite that exhibits tailorable properties in between those currently known for PCL-M and PGS-M alone.