Controllable and durable release of BMP-2-loaded 3D porous sulfonated polyetheretherketone (PEEK) for osteogenic activity enhancement.

Polyetheretherketone (PEEK) is ideal for dental and orthopedic applications because its mechanical properties are similar to cortical bones. However, its inherent inert ability hinders its clinical applications. In this work, bone morphogenetic protein-2 (BMP-2) was immobilized onto the sulfonated PEEK (SPEEK) using lyophilization technology. The surface morphologies of the samples were analyzed by field-emission scanning electron microscopy (FE-SEM), and the chemical compositions were analyzed by energy-dispersive X-ray spectrometry (EDS). The release content of BMP-2 of the samples immersed in the PBS (pH = 7.4) was detected by a human BMP-2 ELISA kit. The results indicated that controllable and durable BMP-2 release was accomplished due to the three-dimensional (3D) network of sulfonated PEEK. The in vitro cellular experiments showed that the BMP-2-immobilized samples significantly enhanced the initial adhesion and spreading of rat bone mesenchymal stem cells (rBMSCs). Moreover, the collagen secretion, extracellular matrix mineralization and ALP activity were also improved. Thus, the BMP-2-immobilized samples greatly promoted the osteogenic differentiation of rBMSCs, which revealed that BMP-2 immobilization paves the way for the use of PEEK in clinical applications.