Implantable medical devices are destined to remain in the body for a lifetime. It is therefore no surprise that an ever increasing number of new materials are being developed for medical use. According to recent literature, desirable properties for bone replacement materials are biocompatibility, meaning that the material is not toxic and does not cause harmful effects when implanted into the human body, a low elastic modulus, meaning that the elasticity of the material matches the elasticity of bone, and corrosion resistance as this affects the durability of the implant.
In the field of metal-based materials, amorphous alloys have shown promising results. Amorphous alloys are novel metallic materials with different atom arrangements that resemble those of glasses, hence the name metallic “glass”. Metallic glass, due to their unique structure, were shown to achieve superior properties when compared to conventional crystalline alloys. In one of Meticuly’s early publications “Characterization and quick screening methodology of novel alloys for biomedical applications using filtered cathodic vacuum arc deposited thin film” a novel alloy series is discussed (Tantavisut et al., 2018). The associated patent US 20220088675 A1 contributed to Meticuly's successful completion of its initial fundraising round.
Developing the next-generation of implants
The research aimed to develop a series of toxic-element-free Titanium-based amorphous alloys. The developed alloy series are Ti44Zr10Pd10Cu6+xCo23-xTa7 (x = 0, 4, 8). Filtered Cathodic Vacuum Arc deposition (FCVA) was used to coat the alloys on glass slides as thin films.
In the experiments, these alloys were compared with Ti-6Al-4V, one of the most popular biomaterials having been used in humans since the 1970’s. The experiments were performed on osteoblast like cells (SaOS-2) to assess the biocompatibility of the alloys with bone cells. The results were astonishing. The experimental alloys exhibited robust cell proliferation, confirmed through Methylthiazol Tetrazolium (MTT) assays, and enhanced cell differentiation, demonstrated by alkaline phosphatase activity tests. The results showed that our novel alloys match, and in some aspects surpass, the performance of the leading medical-grade Ti-6Al-4V alloy. In the related publication, the result of Alizarin red staining analysis showed high calcium mineralization in the novel alloys (Tantavisut et al., 2017). These results indicate that the novel alloys have potential for better osseointegration properties than Ti-6Al-4V.
Additionally, our novel alloys form a TiO2 layer on their surface, significantly boosting biocompatibility and providing antibacterial properties. This protective oxide film prevents the release of copper ions, reducing the risk of cell toxicity. The superior adhesion strength of our thin-film alloys ensures they remain firmly attached to substrates, outperforming commercial medical alloys.
To summarise, the alloys exhibited:
Increased Bone Osseointegration: Enhancing the success rate of implants.
Antibiotic Properties: Reducing the risk of infections.
Improved Mechanical Properties: Strengthening the structural integrity of implants.
In conclusion, these novel amorphous alloys exhibit exceptional biocompatibility, mechanical properties, and antibacterial characteristics, positioning them as promising candidates for a wide range of implant applications, including orthopaedic and dental procedures. Continued research is essential to translate these promising results into clinically viable implants that can eventually improve patient outcomes.
References
Meagher, P., O’Cearbhaill, E. D., Byrne, J. H., & Browne, D. J. (2016). Bulk Metallic Glasses for Implantable Medical Devices and Surgical Tools. Advanced Materials, 28(27), 5755–5762. https://doi.org/10.1002/adma.201505347
Tantavisut, S., Lohwongwatana, B., Khamkongkaeo, A., Bootchai, S., Tangpornprasert, P., Tanavalee, A., & Ittiravivong, P. (2018). Characterization and Quick Screening Methodology of Novel Alloys for Biomedical Applications Using Filtered Cathodic Vacuum Arc Deposited Thin Film. Solid State Phenomena, 283, 78–87. https://doi.org/10.4028/www.scientific.net/SSP.283.78
Tantavisut, S., Lohwongwatana, B., Khamkongkaeo, A., Tanavalee, A., Tangpornprasert, P., & Ittiravivong, P. (2017). The novel toxic free titanium-based amorphous alloy for biomedical application. Journal of Materials Research and Technology, 7. https://doi.org/10.1016/j.jmrt.2017.08.007
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