Synthesis and characterization of poly(ester amide)-based materials for 3D printing of tissue engineering scaffolds

The fabrication of three-dimensional (3D) scaffolds with imprinted physical, chemical and topographical cues is instrumental in tissue engineering strategies to instruct cell function and guide the regeneration of tissues. α-Amino acids based poly(ester amide)s (AAA-PEAs), combining the biocompatibility and biodegradability of polyesters with the superior mechanical properties of polyamides, have emerged as promising scaffolding materials. However, their processing via extrusion-based 3D printing remains challenging due to the lack of polymeric structures with suitable molecular weight and thermal stability. Here, we develop a new library of high molecular weight AAA-PEAs based on L-alanine (PEA-ala), L-alanine/glycine (PEA-ala-gly (75 : 25)) and L-alanine/glycine/jeffamine (PEA-ala-gly-jeff (50 : 25 : 25)) and investigate their performance as polymeric materials for 3D printing against commercially available poly(ε-caprolactone) (PCL). Thermogravimetric analysis reveals the stability of AAA-PEAs at high temperatures, enabling their processing via melt-extrusion printing. Despite differences in complex viscosity between PCL and AAA-PEAs, highlighted by oscillatory rheology measurements, the printability of AAA-PEAs does not seem to be compromised, resulting in 3D scaffolds with good shape-fidelity. Additional physicochemical characterisation of synthesised materials also confirm the possibility of fabricating two-dimensional (2D) films and 3D scaffolds with different mechanical properties, wettability and degradation profiles, depending on the AAA-PEA used. Biological tests carried out in vitro confirm the ability of synthesised materials to support the adhesion and function of metabolically active human bone marrow derived mesenchymal stem cells (hBM-MSCs). The newly synthesised AAA-PEAs expand the range of processable materials via melt-extrusion and contribute to the fabrication of scaffolds with tuneable physicochemical properties for improved tissue regeneration.