In our unit on glasses and ceramics, we learned about bulk metallic glasses, which are amorphous metallic alloys. BMGs have beneficial properties, such as enhanced corrosion resistance, high strength, and high flexibility. Furthermore, the material has high processibility and its unique blow molding fabrication technique allows the shape, size, and surface pattern to be tightly controlled and easily replicated. Bulk metallic glasses can be designed to contain surface modifications and micro and nanopatterns. These surface modifications give the material the unique ability to decrease fusion of foreign body giant cells thereby decreasing the resulting immune response.

In the article “Bulk Metallic Glasses for Biomedical Applications” the authors discuss the versatility of BMGs for implant applications. They examined the biological responses to BMGs in vitro and in vivo and found the material promoted cell adhesion and improved immune responses. Because of the material’s good processing capability and good biocompatibility, the authors proposed that the material could be used to improve a variety of bioengineered medical devices.

One application of BMGs that was discussed in class is a reservoir for controlled drug release. Applied to reproductive health, BMGs could be used to design better drug delivery systems such as IUDs or birth control arm implants. Currently, most IUDs and arm implants are made of very flexible polymers, although BMGs are extremely ductile, which may pose an issue. Some types of  IUDs, such as the ParaGuard, are made with coils of copper. BMGs have been created with copper, as demonstrated by Xu et al. IUDs made of bulk metallic glasses containing copper could provide several advantages over traditional copper IUDs. First, the casting method to create BMGs allows for intricate designs and may simplify the production of the device, which is typically t-shaped. Furthermore, BMGs have higher wear resistance and greater compressive strength, making them potentially safer devices. The use of surface nano- and micropatterns may provide an additional benefit to create IUDs. The copper interferes with sperm movement through the release of copper ions. Increasing the exposed surface area potentially could increase the effectiveness of the IUD, and/or interfere with the sperm. One aspect that must be considered is copper IUDs rely on the immune response to kill sperm. Decreasing the immune response by using more biocompatible material such as the BMG, has the potential to decrease the efficacy of the device. There was no information on designing IUDs with copper BMGs in the literature, although the beneficial characteristics of BMGs make it an interesting application to look into.

Sources:

Schroers J, Kumar G, Hodges TM, Chan S, Kyriakides TR. 2009. Bulk metallic glasses for biomedical applications. Jom. 61(9):21–29

How PARAGARD Works. PARAGARD® (intrauterine copper contraceptive). https://www.paragard.com/how-paragard-works.aspx

Xu D, Lohwongwatana B, Duan G, Johnson WL, Garland C. 2004. Bulk metallic glass formation in binary Cu-rich alloy series – Cu100−xZrx (x=34, 36, 38.2, 40 at.%) and mechanical properties of bulk Cu64Zr36 glass. Acta Materialia. 52(9):2621–24