On the sulphonated PEEK for implant dentistry: Biological and physicochemical assessment

Sulfonated PEEK (sPEEK) has been developed for drug delivery although there is still scarce evidence on its physicochemical and biological properties. The main aim of this study was to assess the cytotoxicity behavior of sPEEK processed for two different sulphonation times. PEEK was functionalized by sulphuric acid treatment for 1 or 1.5 h and then dissolved in dimethylsulfoxide (DMSO). The specimens were characterized by chemical, microstructural, thermophysical, hydrophobic, and roughness analysis. Cytotoxicity assays with fibroblasts followed ISO 10993-5. Thermophysical analyses by TGA and NMR revealed no statistical difference (p > 0,05) in the degree of sulphonation for both processing time points although chemical modifications were detected in the main polymer chain. PEEK surfaces were more hydrophilic than sPEEK surfaces and therefore biological assays revealed a higher cell proliferation on PEEK surfaces when compared to that recorded on sPEEK surfaces. Fibroblasts revealed a higher metabolic activity on PEEK than that on sPEEK specimens for 1 and 3 days of incubation. However, there was a significant increase in cell metabolic activity on sPEEK/DMSO of about 20% compared to that recorded on PEEK for 7 days of incubation. SPEEK specimens showed a limited cytocompatibility probably due to the release of sulfonic compounds to the surrounding medium. The sulphonation method should be adjusted considering different processing time and surface treatment to achieve a high biocompatibility performance of sPEEK for biomedical applications. •Biological and physicochemical behavior of sPEEK was assessed in this study.•The modification of PEEK structure by sulphonation method decreased its wettability and cytocompatibility.•The release of sulfonic products from sPEEK can be toxic for human tissues. However, diferent sulphonation process should be studied to acess sPEEK toxicity.