Chemistry Colloquium - Prof. Julianne Gibbs, University of Alberta

Dec 9, 2022

12:30 PM

Pappajohn Business Building, W10

21 East Market Street, Iowa City, IA 52245

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Prof. Juli Gibbs

The Department of Chemistry presents Prof. Julianne Gibbs, of the Department of Chemistry, University of Alberta, colloquium speaker, presents: "Understanding and Modulating Interactions in Charged Aqueous Systems: From Environmental Remediation of Mining Waste to Nucleic Acid Self-Replication"

Abstract: Environmental and biological chemistry are both largely governed by the interplay between repulsive and attractive forces that are mediated by water. Most of the constituents in these systems are surfaces, polymers or assemblies where charge is concentrated. This concentration of charge presents challenges in trying to study these systems on the molecular scale by using molecular fragments as models for the assemblies/surfaces. As such, the best approaches involve the direct study of interactions at the charged solid or biopolymer interface.

Here I will tell two vignettes about my group’s interest in a) understanding how charged interactions at aqueous surfaces play roles in environmental chemistry and b) modulating the sensitive balance of repulsive and attractive forces in charged biopolymers to generate new functions useful in biodiagnostics.

The first story involves understanding how the interactions of water, ions, and pH combine to influence the charging behavior and structure at mineral interfaces. This work highlights one of the major pitfalls in environmental modeling of aqueous mineral systems, which fail to account for the interactions of water with minerals leading to significant environmental hazards associated with mining. To monitor the structure at the interface we utilize vibrational sum frequency generation as it is intrinsically sensitive to water that has a net alignment. I will discuss the dramatic difference in water structure that emerges when the pH is varied in the presence of monovalent and divalent ions, with direct relevance to mining waste water clean-up strategies. Moreover, I will present some of our most recent work to separate the contributions of water immediately at the surface from adjacent water in the so-called diffuse layer allowing us to refine century-old models of the electrical double layer.

In the second story I will turn to my group’s interest in another charged system: nucleic acid biopolymers. We have shown that we can overcome one of the great challenges in autonomous nucleic acid replication by introducing destabilizing groups into some of the replicating nucleic acid strands. Not only is this of fundamental interest to understanding how replicating systems could have emerged on early Earth, but it also has potential use in point-of-care diagnostics. Using our ability to tune the amount of destabilization we can control at what temperature the nucleic acids of a given sequence best replicate. This has allowed us to generate assays for detecting RNA or DNA biomarkers that operate at room temperature, which is unique amongst most isothermal nucleic acid amplification methods. I will discuss our efforts to optimize our novel replication strategy and introduce room-temperature read-out methods.

Bio: Juli Gibbs is originally from northern Arizona. She received her Bachelor’s degree from Arizona State University in 2000 and then joined the group of SonBinh Nguyen at Northwestern University to pursue graduate research on the development of polymer-DNA hybrid materials with novel recognition properties. After completing her dissertation, Juli worked with Franz Geiger and Karl Scheidt as a Dreyfus Postdoctoral Fellow in Environmental Chemistry. In 2008, she began her independent career at the University of Alberta where she is now an associate professor. Juli has been recognized with multiple awards such as the Petro-Canada Young Investigator Award, the Rising Star Award from Grand Challenges Canada and an Alfred P. Sloan Foundation Research Fellowship. Her research spans the development of new biodiagnostic and therapeutic agents based on DNA nanotechnology to fundamental research aimed at understanding processes at surfaces relevant to biodiagnostics as well as environmental and biological systems.

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