In vitro cytotoxic assessment of a wire arc additively manufactured NiTi wall for biomedical applications

In this study, a NiTi wall was fabricated using wire arc additive manufacturing (WAAM), and its in vitro cytotoxicity was systematically evaluated to assess the suitability of WAAM for processing a biocompatible NiTi alloy. Cytotoxicity testing using the MTT assay on HaCaT cells showed high cell viability of 94.08% and 95.77% at the highest extract concentration, confirming the extracts as non-cytotoxic. XRD analysis revealed retention of the predominant B2 austenitic phase with minor B19' martensite. SEM-EDX and EBSD analyses confirmed a dense and compositionally uniform microstructure with a preferred <101> crystallographic texture along the build direction. Microhardness increased from 288.5 to 373.5 HV along the build height, indicating a stable mechanical response. XPS confirmed the formation of a TiO₂ surface layer, while wettability measurements indicated hydrophilic behaviour. These results confirm that WAAM enables stable fabrication of NiTi while retaining its biological response, demonstrating its suitability for biomedical-related applications.