{"id":54258,"date":"2026-04-17T11:30:59","date_gmt":"2026-04-17T15:30:59","guid":{"rendered":"https:\/\/engineering.jhu.edu\/materials\/?post_type=news&p=54258"},"modified":"2026-04-17T11:30:59","modified_gmt":"2026-04-17T15:30:59","slug":"the-hidden-variable-in-biodegradable-implants-how-metal-structure-shapes-safety","status":"publish","type":"news","link":"https:\/\/engineering.jhu.edu\/materials\/news\/the-hidden-variable-in-biodegradable-implants-how-metal-structure-shapes-safety\/","title":{"rendered":"The Hidden Variable in Biodegradable Implants: How Metal Structure Shapes Safety\u00a0"},"content":{"rendered":"

Doctors insert\u00a0more than\u00a02 million tiny wire mesh tubes, or\u00a0heart stents,\u00a0into Americans\u2019 blood vessels a year\u00a0to treat heart disease, according to health care market research firm\u00a0iData\u00a0Research.<\/span>\u00a0<\/span><\/p>\n

Stents\u00a0are one of many implants used by doctors to support the body while it heals\u00a0from disease or injury\u00a0and,\u00a0for decades, they\u00a0have been\u00a0made from metals that stay in the body for a long time after their job is done.\u00a0Now,\u00a0a\u00a0new generation of biodegradable implants\u00a0made from magnesium are\u00a0gaining ground,\u00a0but researchers\u00a0in the\u00a0Department of Materials Science\u00a0and\u00a0Engineering\u00a0are\u00a0investigating\u00a0how\u00a0the materials\u2019 structure affects\u00a0patient\u00a0outcome.<\/span>\u00a0<\/span><\/p>\n

The\u00a0Johns Hopkins University\u00a0researchers\u00a0led\u00a0by\u00a0Professor\u00a0Tim Weihs\u00a0and\u00a0his\u00a0student\u00a0Sreenivas\u00a0Raguraman\u00a0recently published\u00a0a study\u00a0in\u00a0<\/span>Acta Biomaterialia<\/span><\/i><\/a>\u00a0that\u00a0demonstrated\u00a0that,\u00a0when processed two\u00a0different ways,\u00a0the same\u00a0magnesium-based\u00a0implant\u00a0material can\u00a0have dramatically different outcomes\u00a0in the body.\u00a0The research was conducted\u00a0in collaboration with Professor Roger J. Guillory II and\u00a0PhD\u00a0student Mitchell L. Connon at the Medical College of Wisconsin.<\/span>\u00a0<\/span><\/p>\n

\u201cThis is really important for elderly patients, who may not tolerate multiple procedures well, for soldiers with traumatic injuries, or for athletes who want to recover quickly without permanent hardware,\u201d says Sreenivas Raguraman,\u00a0the lead author on the paper and a materials science\u00a0doctoral\u00a0student at Johns Hopkins.<\/span>\u00a0<\/span><\/p>\n

Raguraman says that these new magnesium-based implants are strong enough to support the body and safe enough to dissolve over time\u00a0to\u00a0avoid long-term complications or\u00a0more surgeries. The FDA recently\u00a0designated\u00a0one of these magnesium-based stents as a\u00a0\u201cbreakthrough\u00a0device.\u201d\u00a0<\/span>\u00a0<\/span><\/p>\n

\u201cI think many people\u00a0assume that if an implant is called\u00a0\u2018biodegradable,\u2019\u00a0it simply dissolves and disappears in a straightforward, harmless way.\u00a0In reality, that\u00a0process is much more complex. How the material breaks down, what it releases, and how the body responds to those degradation products all matter,\u201d says Raguraman.\u00a0\u00a0\u00a0<\/span>\u00a0<\/span><\/p>\n

But Raguraman says to make the\u00a0new\u00a0implants strong enough\u00a0to\u00a0last,\u00a0scientists often add\u00a0small amounts\u00a0of other\u00a0elements, like aluminum.\u00a0That\u2019s\u00a0where the concern comes in. Aluminum has been linked to neurological\u00a0issues and cellular toxicity in\u00a0large amounts.\u00a0<\/span>\u00a0<\/span><\/p>\n

\u201cSo,\u00a0the question we asked was,\u00a0\u2018Does that concern\u00a0actually apply\u00a0here?\u00a0When\u00a0aluminum is present in much smaller amounts?\u2019\u201d Raguraman\u00a0says.\u00a0<\/span>\u00a0<\/span><\/p>\n

Raguraman and the Hopkins researchers took that question a step further and looked at how that material broke down in the body\u00a0\u2014\u00a0how the aluminum was released, if\u00a0it stayed close to the implant,\u00a0and\u00a0whether it entered the bloodstream.<\/span>\u00a0<\/span><\/p>\n

Raguraman says the finding shocked\u00a0him.\u00a0<\/span>\u00a0<\/span><\/p>\n

\u201cEven when the material had the exact same composition and the same amount of aluminum, changing how we processed it altered its internal\u00a0atomic\u00a0structure. And that internal structure\u00a0determined\u00a0how the aluminum was released,\u201d Raguraman says. \u201cWe saw\u00a0very different\u00a0outcomes in the\u00a0mice, yet the only difference was how we made the material.\u201d<\/span>\u00a0<\/span><\/p>\n

Changing the\u00a0way\u00a0they processed the metal alloy turned out to matter a lot. It changed its internal structure. One version of the material released aluminum in a form that entered\u00a0the bloodstream and\u00a0could\u00a0be excreted from the body.\u00a0Another kept most of it localized near the implant site.\u00a0\u00a0It is not yet clear which one of these processes is better for long-term\u00a0health outcomes\u00a0and\u00a0inflammation, and the research is ongoing.\u00a0\u00a0<\/span>\u00a0<\/span><\/p>\n

\u201cThis work provides novel insight into the complex interactions between implant microstructure and the surround biological response,\u201d says\u00a0Professor\u00a0Tim Weihs.\u00a0\u201cWe need to think beyond the mechanical and degradation properties of the implant and focus on the local cellular response as well.\u201d<\/span>\u00a0<\/span><\/p>\n

\u201cThat insight gives us a much more powerful way to design safer medical implants\u201d says Raguraman.\u00a0As a metallurgist, this\u00a0changes\u00a0his approach to the problem. \u201cWe\u2019re\u00a0not just designing materials for structural\u00a0performance;\u00a0we\u2019re\u00a0designing them for how they interact with\u00a0the\u00a0biology\u00a0of the body. And that\u00a0opens up\u00a0a completely new way of thinking about materials science.\u201d<\/span>\u00a0<\/span><\/p>\n

Raguraman\u2019s collaborators Roger Guillory and Mitchell Connon at the Medical College of Wisconsin are now doing studies to try to understand how the body responds to these materials at\u00a0the\u00a0inflammation\u00a0level.<\/span>\u00a0<\/span><\/p>\n

\u201cUnderstanding these interactions, from microstructural manipulation and how it leads to complete physiological\u00a0processing,\u00a0will launch us towards developing the next generation of regenerative metallic biomaterials,\u201d says Guillory.\u00a0<\/span>\u00a0<\/span><\/p>\n

\u201cAt the same time, this\u00a0offers\u00a0an exciting opportunity from a materials design perspective,\u201d says Raguraman, adding that the goal would be to create implantable\u00a0materials that not only provide the right strength and degradation but also lead to\u00a0a better\u00a0biological response.\u00a0\u201cOur aim is to bring these ideas together\u00a0to maximize safer, lasting implants for people.\u201d<\/span><\/p>\n","protected":false},"template":"","class_list":["post-54258","news","type-news","status-publish","hentry","news_categories-research"],"acf":[],"yoast_head":"\nThe Hidden Variable in Biodegradable Implants: How Metal Structure Shapes Safety\u00a0 - Department of Materials Science & Engineering<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/engineering.jhu.edu\/materials\/news\/the-hidden-variable-in-biodegradable-implants-how-metal-structure-shapes-safety\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"The Hidden Variable in Biodegradable Implants: How Metal Structure Shapes Safety\u00a0 - 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