Mechanical tunability of oriented and random electrospun poly(ε-caprolactone) scaffolds via concentration, molecular weight, and environment

TL;DR

This paper presents a framework for tuning the mechanical properties of electrospun PCL scaffolds by adjusting factors like polymer concentration, molecular weight, and fiber orientation.

Contribution

The study integrates multiple tunable parameters into a single framework to achieve a broad mechanical window for PCL scaffolds.

Findings

Oriented fibers show higher stiffness and tensile strength compared to randomly deposited fibers.

Environmental exposure, such as acidic treatments, can reduce scaffold stiffness in a concentration- and temperature-dependent manner.

Abstract

Achieving precise mechanical control in electrospun fibrous scaffolds remains a critical challenge for tissue engineering, where scaffold stiffness, strength, and extensibility must be tailored to diverse biological environments. Here, we establish a systematic framework for tuning the mechanical behavior of electrospun poly(ε-caprolactone) (PCL) fibers by integrating molecular-weight blending, polymer concentration control, fiber orientation, and environmental exposure within a single study. High-molecular-weight PCL (H-PCL) and blends with low-molecular-weight PCL (L-PCL) were electrospun to produce fibers with controlled diameters, morphologies, and orientations. Fiber alignment emerged as the dominant structural factor governing mechanical performance: oriented fibers exhibited substantially higher stiffness (~ 90–140 MPa) and tensile strength (up to ~ 100 MPa), while randomly deposited fibers showed markedly greater extensibility (up to ~ 1000%). Polymer concentration and resulting fiber diameter further modulated stiffness, with optimal mechanical performance observed at intermediate concentrations (~ 10–12% w/v). Molecular-weight blending provided an additional route to tailor fiber morphology and modulus, with oriented fibers reaching peak stiffness at ~ 50–60% H-PCL. Environmental exposure studies revealed that acidic treatments (formic and acetic acid solutions) reduce stiffness in a concentration- and temperature-dependent manner, whereas physiological soaking in phosphate-buffered saline (PBS, 37 °C) largely preserves scaffold integrity. Collectively, the electrospun scaffolds developed here span a broad mechanical window (~ 5–140 MPa). When positioned against literature-reported electrospun PCL scaffolds for cardiac, bone, and muscle tissue engineering, this range bridges multiple application-relevant stiffness regimes. These results provide a unified structure–property framework for designing mechanically tunable PCL fibrous scaffolds across diverse biomedical applications.

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