Spring 2025 Seminar Series

February 12, 2025

Selective Catalytic Transformations of Polyolefins

Aaron Sadow, Ames National Lab and Department of Chemistry, Iowa State University

4:00 p.m., Larrañaga Engineering Auditorium, Centennial Engineering Center

Abstract: We are investigating catalytic materials and methods that regulate the cleavage of C–H bonds or C–C bonds in polyolefins, to introduce functional groups at selected positions or to create narrow distributions of shorter, partially deconstructed chains. This approach involves the design and synthesis of 3D porous inorganic metal oxide architectures which contain catalytic sites in well-defined positions in the material, along with spectroscopic investigations and theoretical models of polymer adsorption and translocation in the pores. In parallel, we are developing catalytic sites and reactions that break C–C and C–H bonds in aliphatic hydrocarbon polymers. As these catalytic sites are incorporated into 3D architectures and studied in polyolefin deconstruction reactions, our team is developing theoretical, kinetic models and in situ spectroscopic methods for studying the ‘macromolecular’ mechanisms that influence the average chain lengths of products and the dispersity of product distributions.

Such approaches using micro or mesoporous materials can lead to processive catalysis, whereby a polymer chain is adsorbed into the pores of the inorganic oxide and is successively cleaved into smaller fragments without release of the ever-shortening polymer chain. Nanoparticles, responsible for C-C cleavage, localized in the pores at uniform distances from the pore mouth, then cleave polyolefin chains into semi-regular smaller chain lengths. We will present our studies of these architectures and catalytic reactions in the selective deconstruction of polyolefins.

February 5, 2025

Membraneless Intracellular Organization: Role of Nucleic Acid Phase Separation

Anisha Shakya, UNM

4:00 p.m., Larrañaga Engineering Auditorium, Centennial Engineering Center

Abstract: Compartmentalization of the cellular interior allows organization of the numerous biochemical processes that cells need for proper function. This can occur with or without lipid membranes. Condensation of biological macromolecules like proteins and nucleic acids through phase separation into liquid-like droplets (biomolecular condensates) has emerged as a central feature of membraneless compartmentalization in cells. Phase separation can allow organization across multiple length scales; ranging from large organelles, such as the nucleolus, to small functional compartments such as transcription “hubs”. Misregulation of this physical phenomenon in cells has also been linked to diseases such as cancer and neurodegenerative diseases. My research has involved elucidating the formation, dynamics, and maintenance of biomolecular condensates, both in vitro and in cells, using modern optical microscopy techniques and a range of biophysical, biochemical, cell biology tools. In this talk, I will summarize my work on understanding the formation and dynamics of nucleic acid-based biomolecular condensates, the effect of the mechanical properties of nucleic acids on tuning condensate properties, and the role of phase separation of DNA-binding proteins such as histones in chromatin organization in the cell nucleus.

Bio: My research program seeks to understand how the multitude of biochemical processes occurring inside a cell are organized in absence of lipid membranes, and how the mis-regulation of such membraneless organization lead to diseases. To achieve this, my program employs a range of interdisciplinary skills such as thermodynamic analysis, database mining and computation, novel optical imaging methods along with in-vitro reconstitution assays and cell biological techniques.

I was born and raised in Nepal, a small beautiful landlocked nation with some of the tallest mountains in the world. I have a B.Sc. in microbiology from Tribhuvan University, Nepal and a B.Sc. in chemistry from McNeese State University, Lake Charles, LA. I obtained my Ph.D. in chemistry from the University of Michigan, Ann Arbor, MI and did postdoctoral trainings at the Institute for Basic Science, South Korea and Northwestern University, Evanston, IL.

At UNM, I am assembling a team of passionate scientists from diverse backgrounds to help expand our knowledge of chemistry and solve some of the challenging problems in human health and diseases.

Currently, outside of science, I love to spend time with my 11-month-old and two Korean cats.

January 29, 2025

High Throughput Free Energy Methods in Drug Discovery

Xiaorong Liu, UNM

4:00 p.m., Larrañaga Engineering Auditorium, Centennial Engineering Center

Abstract: Computational tools have become increasingly indispensable in drug discovery. In particular, physics-based free energy methods have become increasingly practical and effective in structure-based drug design. However, a major bottleneck for current free energy approaches is the computational cost and thus limited throughput, especially when substantial conformational flexibility exists for the receptor and/or the ligand. To address this bottleneck, we have developed multisite lambda dynamics (MSLD)-based methods for rigorous, high-throughput free energy predictions. In this talk, I will discuss the principles of MSLD, and share one of our recent works demonstrating that MSLD is an effective strategy for large-scale free energy calculations to guide the optimization of TSSK1B kinase inhibitors. Furthermore, I will present our recent development to more efficiently sample conformational dynamics and greatly improve the efficiency and robustness of MSLD free energy calculations. Continual development of enhanced sampling in MSLD will be critical for further extending its applicability to traditionally challenging cases in the design of drug molecules, biologics, and functional proteins.

Bio: I grew up in Hubei, China, and obtained my B.Sc. degree in Applied Chemistry from Wuhan University. In 2019, I obtained a Ph.D. degree in Chemistry from the University of Massachusetts Amherst, and my Ph.D. study was focused on developing and applying advanced computational methods to study intrinsically disordered proteins, which play important roles in cellular signaling and regulation and are associated with many human diseases. I was a postdoctoral fellow at the University of Michigan before joining UNM, and my main effort was to develop highly accurate and high-throughput computational methods to design drug molecules. I have been an assistant professor in the Department of Chemistry and Chemical Biology at UNM since August 2024.

January 22, 2025

Innovations in microfluidic systems and nanotechnology for biomedical applications

Xiujun James Li, University of Texas at El Paso

4:00 p.m., Larrañaga Engineering Auditorium, Centennial Engineering Center

Abstract: Recently, fast-growing microfluidic lab-on-a-chip and nanotechnology have caused significant impacts on various disciplines including modern analytical chemistry. Herein, I will highlight several paper/polymer hybrid microfluidic devices and nano-biosensing technology that we recently developed for biochemical and environmental analysis, with a focus on low-cost disease diagnosis, especially for resource-poor settings. Difference chip substrates have different advantages as well as limitations. Paper/polymer hybrid microfluidic devices can draw more benefits from both substrates. We for the first time developed a low-cost photothermal biosensing method for quantitative biochemical analysis using a common thermometer. Integrated graphene oxide nano-biosensors, on-chip DNA amplification, and nanoparticle-mediated photothermal immunosensing will also be introduced toward their applications in point-of-care infectious disease diagnosis and cancer biomarker detection.

Bio: XiuJun (James) Li, Ph.D., is a Full Professor with early tenure in the Department of Chemistry and Biochemistry at the University of Texas at El Paso (UTEP), USA. He is also the Director of Forensic Science Program at UTEP. After he obtained his Ph.D. degree in microfluidic lab-on-a-chip bioanalysis from Simon Fraser University (SFU) in Canada in 2008, he pursued his postdoctoral research with Prof. Richard Mathies at University of California Berkeley and Prof. George Whitesides at Harvard University, while holding a Postdoctoral Fellowship from Natural Sciences and Engineering Research Council (NSERC) of Canada. Dr. Li’s current research interest is centered on the development of innovative microfluidic lab-on-a-chip and nanotechnology for bioanalysis, biomaterial, biomedical engineering, and environmental applications, including but not limited to low-cost diagnosis, pathogen detection, nano-biosensing, genetic analysis, 3D cell culture, tissue engineering, and single-cell analysis, supported by NIH, NSF, CPRIT, DOT, UT System, Philadelphia Foundation, AAFS, and MCA Foundation multiple funding agencies. His lab has extensive experience in point-of-care detection. He pioneered the novel concept of paper/polymer hybrid microfluidic devices; he, for the first time, developed photothermal biosensors for low-cost quantitative analysis using a common thermometer.

Dr. Li has coauthored about 123 scientific publications and 24 patents, including three books from Elsevier on microfluidic devices for biomedical applications. He is an Editorial Board member of multiple journals including Microsystems & Nanoengineering and Scientific Reports from the Nature Publishing Group, Micromachines, Future Science OA, Journal of Analysis and Testing, etc, and an Advisory Board member of Lab on a Chip, Analyst and Sensors & Diagnostics. He is the recipient of the “Bioanalysis New Investigator Award” in 2014, UT STARS Award in 2012, NSERC Postdoctoral Fellow Award in 2009, Chinese Government Award for Outstanding Self-financed Graduate Student Abroad (2004), Outstanding Faculty Dissertation Research Mentoring Award (2016 & 2018, twice), NIH BUILDING Scholar Mentoring Award for Excellence in Student Research Mentoring in 2017, and so on.