Polydopamine/polyvinyl alcohol/graphene oxide transition layer for enhancing adhesive performance of HA coating on Cf/C composites prepared by hydrothermal electrodeposition/hydrothermal treatment

Hydroxyapatite (HA) coatings on carbon fiber-reinforced carbon (C_f/C) composites hold promise for orthopedic implants. However, the interface between HA and C_f/C is prone to delamination, limiting its application. To address this, a polydopamine (PDA)-polyvinyl alcohol (PVA)-graphene oxide (GO) transition layer was introduced to reinforce and toughen HA coatings on C_f/C composites (PDA-PVA-GO/C_f/C) via hydrothermal electro-deposition/post-hydrothermal treatment. For comparison, the PDA and PDA/PVA transition layers were also prepared on C_f/C, designated as PDA/C_f/C and PDA-PVA/C_f/C, respectively. The precursor and transformed coatings obtained were monetite and HA. XRD analyses revealed that PDA and PVA infiltrated the monetite lattice without affecting the HA lattice parameters. Remarkably, scratch tests demonstrated that the HA/PVD-PVA-GO coating on C_f/C exhibited a dense configuration and compact interfacial structure, achieving a maximum critical load of 51.5 N, surpassing other reported electrochemically prepared HA coatings. Moreover, scratch tests indicated a more homogeneous scratch pattern with no sudden delamination of the coating from the matrix. In vitro assessments revealed that all HA coatings with the transition layer exhibited enhanced bioactivity and cell compatibility compared with HA alone. In particular, PDA/PVA/GO-C_f/C exhibited the best superior efficacy in promoting the proliferation of mouse embryonic osteoblast precursor (MC3T3-E1) cells and significantly increased Alkaline phosphatase (ALP) production in rat bone marrow mesenchymal stem cells (BMSCs). These findings underscore the potential of PDA-PVA-GO/C_f/C as a promising biomaterial for bone regeneration.