Teacher Profile – Knecht

BY HOODBHOY

With his ongoing research on biological macromolecules and their ability to construct nanoparticles for specifically targeted applications, Dr. Marc Knecht, an associate professor of Materials Chemistry at the University of Miami, continues to advance and contribute greatly to the growing field of science. In one of his recent investigations, Knecht closely analyzed the interactions and material-specific binding of certain peptides based on their affinity for gold and silver. He discovered that different modes of binding take place on both silver and gold surfaces. These observed differences directly affected the peptide-mediated synthesis of nanoparticles, where contact with the metal surfaces altered the peptide’s ability to cap nanoparticles. As a result of this study, it became clear that the different binding modes on metallic surfaces led to selective binding on certain inorganic surfaces and greatly contributed to nanoparticle nucleation and growth.

One of the main goals of this study, as described by Knecht, was to use peptides commonly found in scientific literature to gain insight into why they bind to metal surfaces (both flat and curved) with nanoparticles. Knecht explained that this study was specifically focused on gold and silver materials mainly because, when they are in their nanoparticle scale — about a billionth of a meter, their optical properties can very easily be controlled. Knecht further explained that, due to these discoveries, researchers now possess newfound abilities such as bending light to create nanomaterials for cloaking.

Knecht is now working to further his topic of study by searching for a biomolecule that controls the specificity of nature. He explained that nature typically designs each protein and enzyme with a specific function. Keeping this in mind, Knecht strives to uncover the basis underlying the specificity of these peptides, namely by examining how some peptides bind to silver while others bind to gold. He also hopes to investigate these peptides’ potential ability to bind to both gold and silver simultaneously. Knecht explained that, if we understand the basis of the selectivity of one peptide binding to silver and the other binding to gold, then we might be able to control such properties by linking those specific peptides together. This would then create two domains at which we could grow particles, essentially allowing us to control the distance between the particles themselves. Knecht aims to extend this idea to multiple particles, such as large three-dimensional lattices, in order to construct nanoparticle assemblies that feature easily-controllable optical properties.

Expanding this study further, Knecht intends to test the responsivity of the linker holding the two peptides together to external stimuli. He would then strike the linker with light in order to change its conformation, causing the whole biomolecule to change conformation as well. Knecht believes that this will grant control of their optical properties and potentially discover other functionalities of the peptide by its positive responses to the external stimuli provided.

One of the greatest challenges faced while conducting his research, Knecht said, was the limited amount of data available for peptides that bind specifically to certain metals. He explained that once the study was tested, the peptides were not as specific as had been anticipated. It is easy to assume that peptides only bind to one material; however, because gold and silver are similar materials, the peptides bound promiscuously between each other. Upon further investigation, he discovered that there are certain peptides that do have some degree of specificity for one metal over another.

While Knecht loves discussing his research, he also enjoys offering advice to undergraduates looking to enter the research field themselves. In regards to getting involved with the right research project, Knecht strongly advised undergraduate students to get involved with a research project they feel passionately about as early as possible in their college career. He explained that it is not always beneficial for students to wait until they are a junior in college to start research because they think they will understand more. “There’s not that much of a difference between a sophomore and a junior,” he stated. “So get in there early and get going now.” Knecht reassured that the process of getting started in a research project might seem daunting at first, but advised that it will get easier with time. “Keep up with it and you’ll learn,” he said. “The more you do, the better off you’ll be. The more you do, the better you will understand.”

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