Talks & Lectures
16 Apr 2021

Polyelectrolyte-Modified Soft and Hard Templates for Environmental and Biomedical Nanomaterial Synthesis

Department of Chemical Engineering and Materials Science

photo of. Geoffrey D. Bothun

Abstract

One of the goals in our group is to create and utilize versatile templating techniques to design nanomaterials that address emerging environmental and biomedical needs. A simple way to modify the surface properties of a soft or hard material is through polyelectrolyte deposition. This process, driven by enthalpic and entropic interactions, creates a surface layer that reflects the charge density of the polyelectrolyte. We use polyelectrolyte deposition to modify “soft” lipid bilayer vesicles (liposomes) and cross-linked protein nanoparticles as well as “hard” magnetic and fractal carbon black nanoparticles in order to create templates that guide the synthesis of gold nanoshells. By tuning the surface properties and synthesis conditions, we are able to obtain a variety of gold nanoshell structures from discontinuous to “spiky” with distinct optical properties. When templating with liposomes for example, which are soft nanoscale capsules with internal aqueous reservoirs, multifunctional colloids are created containing encapsulated iron oxide nanoparticles that can be activated thermally using near-infrared and alternating current electromagnetic fields. With these active triggers, it is possible to control drug release and thermal treatment (hyperthermia) in cell cultures through external stimuli. When templating with “hard” particles, colloidal structures are created that are capable of capturing environmental pollutants and detecting them in situ using surface enhanced Raman spectroscopy (SERS).

Biography

Dr. Geoffrey D. Bothun is a Professor of Chemical Engineering at the University of Rhode Island (URI) and Principal Investigator and Project Director of the Rhode Island National Science Foundation (NSF) Track-1 EPSCoR award. His primary research is in the area of bionanotechnology, utilizing colloidal and interfacial science, self-assembly, and lipid biophysics to design nanotheranostic materials for biomedical applications, to advance the environmental health and safety of nanotechnology, and to create nanomaterials for environmental applications such as pollutant detection and remediation. He has expertise in the areas of heat and mass transfer, membrane separation processes, high-pressure processing including supercritical fluids, and experiential nanotechnology education. Dr. Bothun received undergraduate degrees in chemical engineering and chemistry from the University of Nevada in Reno, and his MS and PhD degrees in chemical engineering from the University of Kentucky. Prior to joining URI in 2006, he was an NSF Discovery Corps Postdoctoral Fellow at North Carolina A&T State University working with the NSF Science and Technology Center for Environmentally Responsible Solvents and Processes.

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