Bioactive PEEK biomaterial surface: Effect of glow discharge plasma-driven nano surface crystallinity alteration

The objective of this paper was to investigate the effects of low-temperature plasma treatment on the surface crystallinity of PEEK and its subsequent impact on bioactivity. PEEK samples were subjected to low-temperature glow discharge air plasma treatment for durations ranging from 5 to 90 min to induce nanocrystalline alterations on the surface of PEEK without changing the bulk mechanical properties. Surface modifications were characterized using various microscopic and spectroscopic methods. In addition, the biological responses were evaluated through biomineralization studies and MTT cell viability assay. Results demonstrated significant alteration in surface crystallinity, topography, and chemistry with increasing plasma exposure time. The treated surfaces exhibited the formation of more defined spherulites, improved hydrophilicity, and roughness. Biomineralization assays exhibited improved apatite formation on treated surfaces, particularly for 15 and 30-min exposure times. MTT assays confirm the cell viability and proliferation changes on plasma-treated PEEK compared to the untreated control. This study highlights the efficiency of low-temperature plasma treatment to enhance PEEK's bioactivity and osseointegration properties in vitro.