A research team led by Professor Fan Yubo and Assistant Professor Wang Xuelin from the School of Engineering Medicine at Beihang University, in collaboration with Dr. Zhang Xinuo from Beijing Chaoyang Hospital, has published groundbreaking findings in the prestigious journal Advanced Functional Materials.

Their study, titled "Injectable Bismuth-Based Composite Enable Bone Defect Repair for Osteosarcoma Treatment and Mild Magnetothermal Bone Regeneration," introduces a novel injectable bismuth-based composite material, BiInSn-PMMA composites (BPCs), which integrates low-melting-point bismuth alloys with clinically used polymethyl methacrylate (PMMA) bone cement. This innovative material offers a multifunctional solution for bone defect repair, osteosarcoma treatment, and mild magnetothermal bone regeneration.

Fig.1 Synthesis and characterization of BiInSn-PMMA composites

The newly developed BPCs demonstrate remarkable properties, including a 252% increase in compressive strength compared to pure bismuth alloys. This innovative material can be precisely injected into bone defects via minimally invasive procedures, eliminating the need for open surgeries typically required with traditional metal implants. By leveraging an alternating magnetic field, the composite generates controlled magnetothermal effects, enabling dual functionality: killing tumor cells at 43°C while promoting bone regeneration at 41°C through mild hyperthermia.

Fig.2 BPC materials implantation in bone defects

One of the key challenges addressed by this research is the limitation of conventional materials such as titanium alloys, which suffer from stress shielding due to elastic modulus mismatch, and PMMA bone cements, which cause thermal damage to tissues during curing. The incorporation of PMMA into the bismuth alloy not only enhances mechanical strength but also significantly reduces the exothermic heat during curing, keeping the maximum temperature below 45°C and minimizing thermal risks. Long-term in vivo experiments confirm the material's stability, with no significant displacement observed over six months, demonstrating its ability to provide durable bone filling and regeneration.

Fig.3 Results of mild heating-induced bone regeneration of in vivo and in vitro studies

Histological analysis further reveals that the mild magnetothermal effect promotes bone tissue regeneration when applied under alternating magnetic fields. Comprehensive safety evaluations, including ion release concentration, cytotoxicity assays, and assessments of liver and kidney function in rats, confirm the excellent biocompatibility of the BPCs. These findings highlight the potential of the injectable bismuth-based composite as a versatile tool for integrating bone tumor treatment and regenerative therapy.

This study addresses critical clinical needs by overcoming the limitations of traditional bone repair materials, such as the requirement for open surgery and the lack of biological functionality in PMMA cements. By combining the unique injectability and magnetothermal properties of low-melting-point bismuth alloys with the mechanical advantages of PMMA, the researchers have pioneered a new paradigm in minimally invasive, in situ bone repair. Looking ahead, the integration of this technology with intelligent surgical navigation systems could pave the way for automated, precision orthopedic surgeries.

The research received substantial support from Professor Liu Jing and his team at Tsinghua University, and was supported by grants from the Beijing Natural Science Foundation, the National Natural Science Foundation of China, and other funding sources.

Link to the article: https://doi.org/10.1002/adfm.202501317

Editor: Han Xu