Atmospheric Pressure Plasma Treatment of Regenerated Silk Fibroin Films: Surface Activation, Structural Reorganization, and Mechanical Enhancement

ABSTRACT

In this article, regenerated silk fibroin (SF) films were modified using atmospheric‐pressure dielectric barrier discharge (DBD) plasma to enhance their physicochemical, structural, and mechanical properties for potential biomedical applications. Plasma treatment was performed using an argon–oxygen gas mixture under optimized operating conditions. The plasma‐induced modifications were systematically characterized by water contact angle measurements, attenuated total reflectance Fourier‐transform infrared (ATR–FTIR) spectroscopy, atomic force microscopy (AFM), scanning electron microscopy coupled with energy‐dispersive x‐ray spectroscopy (SEM–EDS), x‐ray diffraction (XRD), and uniaxial tensile testing. Plasma treatment markedly increased the surface wettability, reducing the water contact angle from approximately 80° to 20°. Quantitative AFM analysis revealed a decrease in the mean surface roughness (Ra) from 9.64 to 7.32 nm, indicating a measurable change in nanoscale surface topography under the selected treatment conditions. ATR–FTIR analysis revealed subtle changes in the surface chemical environment while preserving the characteristic molecular structure of silk fibroin. XRD analysis demonstrated an increase in crystallinity from 37.3% to 46.3%, indicating improved molecular ordering of the existing crystalline domains without the formation of new crystalline phases. These structural changes were accompanied by enhanced mechanical performance, with Young's modulus increasing from 3.30 to 4.20 GPa and tensile strength from 53.46 to 70.59 MPa, while the elongation at break remained essentially unchanged. The combined results demonstrate that atmospheric‐pressure DBD plasma provides an effective, environmentally friendly, and solvent‐free post‐treatment strategy for engineering the physicochemical, structural, and mechanical properties of RSF films without compromising their structural integrity. The simultaneous improvement in surface hydrophilicity, molecular organization, and mechanical performance highlights the potential of plasma‐treated silk fibroin films for advanced biomedical applications, including tissue engineering, wound healing, and implantable biomaterials.