Making magnetic biomaterials

(Press-News.org) What if doctors could guide life-saving treatments through the body using only a magnet? 

An interdisciplinary collaboration at the University of Pittsburgh’s Swanson School of Engineering is bringing that concept closer to reality with the development of silk iron microparticles (SIMPs)—tiny, magnetic, and biodegradable carriers designed to precisely deliver drugs and treatments to sites in the body like aneurysms or tumors. 

Led by Pitt alumna Ande Marini (BioE PhD ‘25), now a postdoctoral scholar in cardiothoracic surgery at Stanford University, David Vorp, John A. Swanson Professor of bioengineering, and Justin Weinbaum, research assistant professor of bioengineering, the team’s results, “Chemical Conjugation of Iron Oxide Nanoparticles for the Development of Magnetically Directable Silk Particles” (doi.org/10.1021/acsami.4c17536), were published in the February edition of ACS Applied Materials & Interfaces. 

Marini’s team was inspired to develop these particles as part of their lab’s mission to improve treatments for abdominal aortic aneurysms (AAA), which can be life-threatening if left untreated and lead to nearly 10,000 deaths per year. By enabling early stage, noninvasive delivery of regenerative therapies using extracellular vesicles—membrane capsules that can facilitate intercellular communication—they hope to ultimately reduce the need for surgical intervention for AAA. 

“We want to find a way to deliver extracellular vesicles to the site of an abdominal aortic aneurysm in the least invasive way possible.” Vorp said. “We envisioned that we could inject extracellular vesicles onto a carrier and then somehow guide the carrier to the outside of the aortic wall, so we came up with the idea of using magnetic attraction.”

To create the magnetic particles, the team collaborated with Mostafa Bedewy, associate professor of mechanical engineering & materials science at the Swanson School, and Golnaz Tomaraei (IE PhD ‘23), Pitt alumna and Bedewy’s former PhD student. The duo’s expertise in nanomaterials and nanofabrication helped the team create the magnetic nanoparticles, which are roughly one-hundred-thousandth the width of a human hair. At that extremely small scale, nanomaterials can be manipulated to take on unique properties, such as magnetic responsiveness. 

“Our role was to synthesize magnetic nanoparticles with the right properties and bond them to the silk so they’d stay attached during movement,” Bedewy said. “You can think of it like towing cargo—we created the particles to carry drugs, and the nanoparticles are the tow hook.”

Magnetically directable materials have previously been utilized for a variety of medical applications, but the team’s unique approach was to create the SIMPs by chemically conjugating the magnetic nanoparticles to silk—an FDA approved, biocompatible material—using the chemical compound glutathione. 

“We bridged biomaterials and chemical conjugation to create particles that could be magnetically guided,” Marini said. “By chemically bonding iron oxide nanoparticles to the regenerated silk fibroin, we enhanced their magnetic movability so we can potentially localize them externally to a site of interest in the body. ” 

This research opens the door to a wide range of future applications—from targeted cancer therapies to regenerative treatments for cardiovascular disease. With the ability to magnetically guide the particles, the next step is loading them with therapeutic cargo.

“With this paper, we’re showing that we can create an empty carrier that can be magnetically moved,” Marini said. “The next step is figuring out what kind of cargo we can load—regenerative factors, drugs, or other materials people want to magnetically localize. Whether it’s delivering cancer drugs with fewer side effects or slowing down tissue degradation in aneurysms, this technology has broad potential for regenerative medicine.”

At the nanoscale, these findings also help Bedewy’s team continue to tailor the particles’ molecular structure and control their drug release rates for enhanced biomedical applications. 

“We're trying to create a toolbox of treatments, and in materials science, there's a lot of room for making more tools that can be useful for medical doctors and bioengineers to help create different ways of resolving problems in the body,” Bedewy said. “This is an exciting project where people with very different sets of expertise came together to solve a problem and produce an outcome that could potentially have an immense impact on human lives.” 

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