“Silk is one of my favorite polymers,” declared David Kaplan, the noted biomedical engineer, at the outset of a captivating talk on campus this week about his decades-long drive to turn “a high-volume commodity” into a versatile biomaterial.
Kaplan, the Stern Family Endowed Professor of Engineering at Tufts University, was the featured speaker this year at the Marino Xanthos Memorial Lecture, an annual series dedicated to the late chemical, biological and pharmaceutical engineering professor, remembered admiringly by colleagues as NJIT’s “polymers guru.” The lectures cover a wide range of topics in solid and fluid mechanics, as well as polymer science and engineering; this year’s lecture would have been “near and dear” to his father, noted Harris Xanthos, himself a scientist, in introductory remarks.
When Kaplan began his study of silk, little was known about the chemical and biophysical structure of the water-resistant protein, produced by insects, spiders and, most notably, the cocoon-spinning larvae of the silkworm. At the time, its only medical application was as sutures. And while surgeons liked the ease of tying knots with silk thread, they were less happy that it did not degrade in the body and required removal. He set about to change that.
Calling silk “one of the most hydrophobic proteins found in nature,” Kaplan began by studying its structure and learning how to capture its central insoluble protein – fibroin – in a solution that he could then convert to a gel with many uses, such as injectable foams to fill cavities and defects in the body while natural tissue regenerated. Critically, in its new form, it degraded.
Over the years, Kaplan and his colleagues have learned to make harder structures as well – molds, bone screws and other orthopedic repair devices and degradable implants – that are highly functional, especially with their capacity to include antibiotics to ward off infections and other medications. More recently, the team has taken to 3D-printing devices, including tubes that can repair multiple severed blood vessels at the same time, a massive saving of time and labor for hand surgeons, for example.
Kaplan specializes in biopolymer engineering with a specific focus on collagens and elastins, in addition to silk. His research group emphasizes their use as biomaterials and in tissue engineering and regenerative medicine, and they continually look to expand the boundaries of these materials, which now include implantable optical and electronic devices that can be preprogrammed to perform a variety of functions.
“What I find most remarkable about David’s research is his ability to move with ease from fundamental concepts to practical and important applications, in this case ranging from medical implants, to drug delivery systems, to biocompatible scaffolding structures, to fiberoptic and electronic devices. This is a rare gift,” noted Piero Armenante, distinguished professor of chemical engineering at NJIT and chair of the Marino Xanthos Memorial Lecture Series.
Xanthos, a beloved mentor to a generation of graduate and undergraduate students, was a professor at NJIT for nearly two decades and, later in his career, the associate provost for Graduate Studies, a position he held until his death in 2013. Among his many commitments to the NJIT community, he served as the director of the Polymer Engineering Center, as chair of the Committee of the Materials Research Council, as the senior technical adviser to the Polymer Processing Institute (PPI) at NJIT, and as the faculty advisor to the NJIT Student Chapter of the Society of Plastics Engineers. As NJIT President Joel Bloom noted at the lecture, he was also intent on creating a diverse body of students.
As Armenante put it, “Marino was not only a scholar and a colleague in my department, but also a gentleman and a friend to so many of us."
As a researcher, Xanthos was known for his polymer blends, polymer composites and polymer foams expertise, and his studies on polymer modification through the use of functional particulate additives and reactive extrusion processes, which he also applied to the processing of pharmaceutical oral dosage forms. He became a Fellow of the Society of Plastics Engineers in 2003 and received the NJIT Board of Overseers Harlan J. Perlis Award that same year in recognition of his exemplary scholarship and outstanding research in the field of polymers. He served as the U.S. representative to the Board of the Polymer Processing Society since 2005. In 2010, he received the Heinz List Award in recognition of his outstanding achievements in reactive processing and devolatilization.