Atmospheric-Pressure Plasma-Modified NiTi Surfaces with Tunable Wettability for Optimized Cellular Response and...

The biological performance of NiTi alloys is governed by surface-mediated interactions that control protein adsorption, cellular behavior, and blood compatibility. In this study, atmospheric-pressure plasma treatment was employed to modify NiTi surfaces and generate distinct wettability states (hydrophilic, intermediate, and hydrophobic). Surface properties were systematically characterized by contact angle measurements, surface free energy determination, and protein adsorption analysis to elucidate early biointerfacial responses. Cellular interactions were investigated using normal human dermal fibroblasts (NHDF), assessing cell adhesion, morphology, proliferation, and cytotoxicity through direct and extract-based assays. Hemocompatibility was evaluated using a custom high-speed rotor system combined with fluorescent labeling to quantify coagulation activation under dynamic conditions. Plasma-induced modulation of surface wettability significantly altered protein adsorption profiles, fibroblast responses, and platelet activation. Hydrophilic and intermediate surfaces promoted enhanced cell spreading and proliferation, whereas hydrophobic surfaces exhibited increased platelet activation. These findings demonstrate that plasma-engineered control of NiTi surface wettability enables selective regulation of cellular and blood responses, providing a versatile strategy for optimizing the biocompatibility of NiTi-based biomedical implants.