Bismuth chalcogenides: multifunctional enhancement of radiopacity, mechanical resilience, and osteogenesis in PMMA bone cements for vertebroplasty

Abstract

Current polymethyl methacrylate (PMMA) bone cements face significant trade-offs between radiopacity, mechanical strength, and biocompatibility when incorporating conventional additives like barium sulfate. This study introduces bismuth chalcogenides (Bi₂X₃, X = O, S, Se) as advanced multifunctional radiopacifiers for PMMA bone cement, identifying Bi₂S₃ as a breakthrough candidate. At 20 wt% loading, Bi₂S₃–PMMA achieves a compressive strength of 82.4 ± 3.1 MPa—exceeding the clinical threshold (70 MPa)—while matching the radiopacity of commercial 30% BaSO₄–PMMA. The composite exhibits exceptional biocompatibility, maintaining >95% cell viability and reducing Bi³⁺ ion leaching to 0.424 ppm, significantly lower than levels observed with Bi₂O₃ (9.495 ppm) and Bi₂Se₃ (0.607 ppm). Notably, Bi₂S₃–PMMA significantly enhances osteogenesis, inducing a 2.3-fold increase in alkaline phosphatase activity in bone marrow mesenchymal stem cells compared to unmodified PMMA. Radiographic analyses confirm superior visibility across clinical X-ray energies (80.9–140.9 kV), and three-point bending tests reveal a 25% increase in fracture toughness (work of fracture, WOF = 1.8 kJ m⁻²) over BaSO₄–PMMA. These results establish Bi₂S₃–PMMA as a next-generation bone cement that resolves the longstanding compromise between mechanical integrity, imaging capability, and bioactivity. Owing to its balanced performance, this material holds transformative potential for vertebroplasty, spinal surgeries, and load-bearing orthopedic applications.