Novel Carboxylation Method for Polyetheretherketone (PEEK) Surface Modification Using Friedel-Crafts Acylation.

Recently, polyetheretherketone (PEEK) has shown promising dental applications. Surface treatment is essential for dental applications owing to its poor surface energy and wettability; however, no consensus on an effective treatment method has been achieved. In this study, we attempted to carboxylate PEEK sample surfaces via Friedel-Crafts acylation using succinic anhydride and AlBr3. The possibility of further chemical modifications using carboxyl groups was examined. The samples were subjected to dehydration-condensation reactions with 1H,1H-pentadecafluorooctylamine and N,N'-dicyclohexylcarbodiimide. Furthermore, the sample's surface properties at each reaction stage were evaluated. An absorption band in the 3300-3500 cm-1 wavenumber region was observed. Additionally, peak suggestive of COOH was observed in the sample spectra. Secondary modification diminished the absorption band in 3300-3500 cm-1 and a clear F1s signal was observed. Thus, Friedel-Crafts acylation with succinic anhydride produced carboxyl groups on the PEEK sample surfaces. Further chemical modification of the carboxyl groups by dehydration-condensation reactions is also possible. Thus, a series of reactions can be employed to impart desired chemical structures to PEEK surfaces.

Bioactive Polyetheretherketone with Gelatin Hydrogel Leads to Sustained Release of Bone Morphogenetic Protein-2 and Promotes Osteogenic Differentiation.

Polyetheretherketone (PEEK) is one of the most promising implant materials for hard tissues due to its similar elastic modulus; however, usage of PEEK is still limited owing to its biological inertness and low osteoconductivity. The objective of the study was to provide PEEK with the ability to sustain the release of growth factors and the osteogenic differentiation of stem cells. The PEEK surface was sandblasted and modified with polydopamine (PDA). Moreover, successful sandblasting and PDA modification of the PEEK surface was confirmed through physicochemical characterization. The gelatin hydrogel was then chemically bound to the PEEK by adding a solution of glutaraldehyde and gelatin to the surface of the PDA-modified PEEK. The binding and degradation of the gelatin hydrogel with PEEK (GPEEK) were confirmed, and the GPEEK mineralization was observed in simulated body fluid. Sustained release of bone morphogenetic protein (BMP)-2 was observed in GPEEK. When cultured on GPEEK with BMP-2, human mesenchymal stem cells (hMSCs) exhibited osteogenic differentiation. We conclude that PEEK with a gelatin hydrogel incorporating BMP-2 is a promising substrate for bone tissue engineering.

Stem Cell Transplantation and Cell-Free Treatment for Periodontal Regeneration.

Increasing attention has been paid to cell-based medicines. Many in vivo and in vitro studies have demonstrated the efficacy of stem cell transplantation for the regeneration of periodontal tissues over the past 20 years. Although positive evidence has accumulated regarding periodontal regeneration using stem cells, the exact mechanism of tissue regeneration is still largely unknown. This review outlines the practicality and emerging problems of stem cell transplantation therapy for periodontal regeneration. In addition, possible solutions to these problems and cell-free treatment are discussed.