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

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.