The effects of three cold plasma treatments on the osteogenic activity and antibacterial property of PEEK.

ABSTRACT

OBJECTIVE: This study examines the differences in osteogenic activity and antibacterial property among polyetheretherketone (PEEK) treated by three types of cold plasma. METHODS: Standard PEEK specimens were randomly assigned to four groups, which were named according to the treatment PEEK-C (untreated), PEEK-A (Ar cold plasma treatment), PEEK-N (N2 cold plasma treatment), and PEEK-AN (90% Ar and 10% N2 mixed cold plasma treatment). Physical and chemical properties of the specimen surfaces were determined by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and drop shape analyzer (DSA). MC3T3 osteoblasts were used in vitro to determine the osteogenic activity by cell adhesion morphology observation, cell counting-kit 8 (CCK-8) assay, and alkaline phosphatase (ALP) activity assay. Streptococcus mutans and Staphylococcus aureus were used in vitro to determine the antibacterial property by a plate colony-counting method and bacterial adhesion morphology observation. RESULTS: SEM and AFM analysis showed that the PEEK-C surface was smooth, whereas matrix-arranged nanoprotrusions appeared on the surface of the experimental groups scaly nano-protrusions appeared on the PEEK-A and PEEK-AN surfaces, while dendritic nanoprotrusions appeared on the PEEK-N surface. Among the experimental groups, PEEK-AN had the finest surface nanoprotrusions. The roughness of the experimental groups increased compared with the PEEK-C group the PEEK-N group was the roughest with a Ra of 192.60 ± 5.89 nm and PEEK-A was the smoothest with a Ra of 99.60 ± 5.43 nm. The hydrophilicity of the experimental groups was significantly enhanced compared with the PEEK-C group, among which, PEEK-N was the strongest and PEEK-A the weakest. The osteogenic activity and antibacterial property of the experimental groups displayed a remarkable increase compared with the PEEK-C group. Among the experimental groups, PEEK-N displayed the best osteogenic activity while PEEK-AN possessed the strongest antibacterial property. The osteogenic activity and antibacterial performance of PEEK-A were the weakest. Among these treatments, the N2 cold plasma treatment was the most suitable modification method for PEEK application in dental implant. SIGNIFICANCE: Cold plasma treatment is a promising method to improve PEEK osteogenic activity and antibacterial properties. This study provides a theoretical basis for future research on PEEK cold plasma treatment.