A biomimetically hierarchical polyetherketoneketone scaffold for osteoporotic bone repair

A polydopamine-assisted strontium-substituted apatite coating for titanium promotes osteogenesis and angiogenesis via FAK/MAPK and PI3K/AKT signaling pathways

Early osteointegration is essential for biomedical implants. Surface modifications can significantly compensate for an implant's lack of biocompatibility and osteo-differentiation. They can also be designed to promote angiogenesis in order to assist osteogenesis and ultimately facilitate bone regeneration. In this study, a polydopamine-assisted strontium-substituted apatite coating (Ti@PDA + SrHA) was fabricated on a multifunctional titanium implant to induce both angiogenic and osteogenic abilities for rapid osseointegration. Polydopamine and Sr-substituted hydroxyapatite were coated on the implant through biomineralization. The in vitro results showed that Ti@PDA + SrHA improved cell adhesion and increased the proliferation of rat bone marrow-derived mesenchymal stem cells (rBMSCs) and human umbilical vein endothelial cells (HUVECs). Ti@PDA + SrHA upregulated the expression of ALP activity and osteogenic genes in rBMSCs and elevated angiogenic genes in both rBMSCs and HUVECs. Mechanically, the FAK/MAPK signaling pathway was activated in rBMSCs, and the PI3K/AKT signaling pathway was activated in both rBMSCs and HUVECs. Consistent with these findings, Ti@PDA + SrHA accelerated new bone formation and rapid osseointegration in the femoral condyle implantation study with good stability. Overall, we fabricated a multifunctional biocompatible implant with better angiogenic and osteogenic performance compared to the non-coated implant.

Nutrient Element Decorated Polyetheretherketone Implants Steer Mitochondrial Dynamics for Boosted Diabetic Osseointegration

As a chronic metabolic disease, diabetes mellitus (DM) creates a hyperglycemic micromilieu around implants, resulting inthe high complication and failure rate of implantation because of mitochondrial dysfunction in hyperglycemia. To address the daunting issue, the authors innovatively devised and developed mitochondria-targeted orthopedic implants consisted of nutrient element coatings and polyetheretherketone (PEEK). Dual nutrient elements, in the modality of ZnO and Sr(OH)2 , are assembled onto the sulfonated PEEK surface (Zn&Sr-SPEEK). The results indicate the synergistic liberation of Zn2+ and Sr2+ from coating massacres pathogenic bacteria and dramatically facilitates cyto-activity of osteoblasts upon the hyperglycemic niche. Intriguingly, Zn&Sr-SPEEK implants are demonstrated to have a robust ability to recuperate hyperglycemia-induced mitochondrial dynamic disequilibrium and dysfunction by means of Dynamin-related protein 1 (Drp1) gene down-regulation, mitochondrial membrane potential (MMP) resurgence, and reactive oxygen species (ROS) elimination, ultimately enhancing osteogenicity of osteoblasts. In vivo evaluations utilizing diabetic rat femoral/tibia defect model at 4 and 8 weeks further confirm that nutrient element coatings substantially augment bone remodeling and osseointegration. Altogether, this study not only reveals the importance of Zn2+ and Sr2+ modulation on mitochondrial dynamics that contributes to bone formation and osseointegration, but also provides a novel orthopedic implant for diabetic patients with mitochondrial modulation capability.

Robust and Multifunctional Porous Polyetheretherketone Fiber Fabricated via a Microextrusion CO2 Foaming

Fabrication of multifunctional porous fibers with excellent mechanical properties has attracted abundant attention in the fields of personal thermal management textiles and smart wearable devices. However, the high cost and harsh preparation environment of the traditional solution-solvent phase separation method for making porous fibers aggravates the problems of resource consumption and environmental pollution. Herein, a microextrusion process that combines environmentally friendly CO₂ physical foaming with fused deposition modeling technology is proposed, via the dual features of high gas uptake and restricted cell growth, to implement the continuous production of porous polyetheretherketone (PEEK) fibers with a production efficiency of 10.5 cm s^-1 . The porous PEEK fiber exhibits excellent stretchability (234.8% strain) and good high-temperature thermal insulation property. The open-cell structure on the surface is favorable for the adsorption to achieve superhydrophobicity (154.4°) and high-efficiency photocatalytic degradation of rhodamine B (90.4%). Moreover, the parameterized controllability of the cell structure is beneficial to widening the multifunctional window. In short, the first porous PEEK physical foaming fiber, which opens up a new avenue for the application expansion, especially in the medical field, is realized.