Bioactivated polyetheretherketone scaffold able to generate mild heat for promoting bone regeneration via activating MAPK/ERK signaling pathway

Photothermal therapy (PTT) is a desirable way to attain on-demand hyperthermia owing to the heat generated by photothermal materials absorbing near-infrared) light. The mild heat (42 ± 0.5 °C) can not only accelerate bone tissue regeneration but also promote the release of bioactive ions from biomaterials. Based on this one-stone-two-birds strategy, a 3D printed PEEK-graphene composite scaffold (PG) with hydroxyapatite (HA) coating (PGH) for photothermally remote control of bone regeneration was well designed in this study. The results showed that the HA coating on PGH could release Ca2+ and PO43– ions easily under NIR irradiation, which was ascribed to the mild heat generated from graphene in the composite scaffold. The mild heat and the boosted Ca2+/PO43– release could synergistically enhance the bone regeneration ability both in vitro and in vivo. The underlying mechanism was further explored and confirmed to be closely related to the upregulation of HSP 70, by which the MAPK/ERK signaling pathway was activated selectively. The favorable results demonstrate that the 3D-printed PEEK/graphene composite scaffold is promising in the applications of bone defect repair.