Synthetic Memory: A Key Link Between Biocatalytically Synthesized Polyesters and Melt Electrowriting Performance

Abstract

The biocatalytic synthesis of polycaprolactone (PCL) and its copolymers has garnered significant attention due to their reduced toxicity and enhanced 3D processability compared to metal-catalyzed alternatives. The objective of this study is to employ biocatalysts-citric acid (CA), glycolic acid (GA) and salicylic acid (SAA)-and explore their catalytic effects on the synthesis of poly(epsilon-caprolactone) (PCL) and poly(epsilon-caprolactone)-b-poly(delta-valerolactone) (PCL-b-PVL) block copolymers. Additionally, we aimed to examine the link between synthetic memory of resultant PCL and PCL-b-PVL polymers and their melt electrowriting performance. Nuclear magnetic resonance analysis confirms successful synthesis of copolymers by monitoring signals of hydrogens at 2.30 ppm. Differential scanning calorimetry results reveal shifts in thermal properties of copolymers upon varying biocatalysts CA-, SAA- and GA-catalyzed copolymers exhibit Tm values between similar to 52 and 54 degrees C. Melt electrowriting (MEW) results demonstrate that catalyst selection plays significant role in fiber morphology and scaffold architecture, with GA- and CA-catalyzed copolymers exhibiting finer fibers (5-8 mu m), while SAA led to thicker fibers (similar to 12 mu m) and reduced spacing. Moreover, precipitation solvents MeOH and acetonitrile (ACN) affect fidelity, with ACN-prepared scaffolds exhibiting more uniform fiber diameters. Atomic force microscopy imaging of electrowritten scaffolds made of ACN- and MeOH-precipitated PCL-b-PVL both exhibit large (>15 mu m) and smaller (<10 mu m) spherulitic structure as major topological features. These findings confirm that the synthetic memory of polyesters-governed by catalyst choice and processing conditions-directly influences their printability, making them promising candidates for MEW-based biomedical scaffolds in tissue engineering, where fine fiber morphology and architectural fidelity are essential for cell attachment and tissue regeneration.