Clark Vu: Bottlebrush polymer research at Virginia Tech could help drug delivery in patients

Clark Vu researches bottlebrush polymers, investigating the properties that influence their self-assembly into larger aggregates. Photo courtesy of Clark Vu. — Clark Vu works with bottlebrush polymers to study the properties that affect how they self-assemble to create larger aggregates. Photo courtesy of Clark Vu.

This piece was written in the fall of 2024 by GRAD 5144 (Communicating Science) student Danielle Fitzgerald as part of an assignment to interview a classmate and write a news story about his research.

Clark Vu works with microscopic bottlebrush polymers that are shaped like Christmas trees. That's not so we can hang ornaments on the polymer; the shape is important because it influences how the subunits of the polymer put themselves together in water to create larger structures.

Vu, a fourth-year Ph.D. student in Virginia Tech’s Macromolecular Innovation Institute, custom designs polymers to answer important research questions about their physical properties. Originally from Texas, Vu has a chemical engineering degree from the University of Texas at Austin, where he got his first taste of research as an undergraduate student in enhanced oil recovery.

After graduating, Vu signed on as a process engineer at an intravenous drug manufacturer. After five years in the industry, Vu’s curiosity resulted in his return to research. Vu brought knowledge of nanoparticles and polymers from his undergraduate research to Virginia Tech, where he has since learned how to make more complex polymers using advanced techniques, including one called ring-opening metathesis polymerization. Vu works under the supervision of Virginia Tech chemistry professor John Matson, a pioneer in the technique.

An illustration of two types of Christmas tree bottlebrush polymers, a cylindrical bottlebrush polymer, and the various micelles and vesicles they form. Illustration courtesy of Clark Vu. — Two types of Christmas tree bottlebrush polymers, a cylindrical bottlebrush polymer, and the types of micelles and vesicles that form from them. Illustration courtesy of Clark Vu.

Vu works with polymers that are visually similar to the bottlebrush plant, which can be found in the Hahn Horticulture Gardens at Virginia Tech. Bottlebrush plants, and later the polymer, get their name from their visual appearance; they have a central stem (the backbone) with tough, needle-like protrusions. Unlike the plant, the nanostructure of the bottlebrush polymers Vu works on can only be seen under an advanced electron microscope. Bottlebrush polymers are a step forward from traditional linear polymers and have many new and exciting applications, Vu said.

In the lab, Vu systematically studies the structure of bottlebrush polymers and examines how changing their shape affects the morphology, or form, of the larger aggregates that self-assemble when placed in water. He makes bottlebrush polymers with Christmas tree and cylindrical shapes, both of which have both polar and nonpolar regions that affect how they come together to form larger aggregates. When he puts the Christmas tree and cylindrical shaped polymers into water, they clump to form the spherical micelles, worm-like micelles, or vesicles shown in the illustration. The shape and form of these aggregates is determined by the structure and properties of the subunit bottlebrush polymers.

Virginia Tech is one of only a handful of universities worldwide investigating bottlebrush polymers with a Christmas tree shape. Their formation requires high-quality macromolecules and unique techniques learned only through extensive training. Vu’s study helps answer fundamental questions about how the bottlebrush polymer's structural parameters (e.g., shape) affect the polymeric self-assembly's morphology. Vu’s study of bottlebrush polymers may lead to achievements in targeted drug delivery, improving treatments for various diseases.