KEYNOTE: Strategic Routes to TPE Designs for Broad-Spectrum Antimicrobial Performance

Abstract

Some of the challenges currently facing the global community are becoming increasingly life-threatening. For instance, infectious microbes such as SARS-CoV-2 and MRSA constitute major healthcare concerns as invisible predators primarily, but not restricted to, stalking the elderly and immune-compromised. Although SARS-CoV-2, for instance, primarily spreads by dispersed water droplets or aerosols, evidence reveals that the virus can survive on surfaces for up to several days, in which case transmission can occur upon contact with contaminated surfaces. In response, various surface-disinfecting methods involving nanoparticles or chemical functionalization have been proposed to combat this menace, but many are either limited to specific microbes or promote environmental contamination. In this work, we discuss two promising antimicrobial strategies in which several thermoplastic elastomers (TPEs) are utilized as exemplars to demonstrate their potential. The first focuses on embedding photosensitive dye molecules capable of generating singlet oxygen, a strong oxidizing agent, into a polyolefin-based TPE. In the presence of molecular oxygen and incoherent visible light, this system inactivates at least 99.9999% of two Gram-positive bacterial strains, as well as at least 99.9% of three Gram-negative bacterial strains and three virus strains, in ca. 1 h under the conditions employed. Alternatively, a vastly different method employs an anionic TPE that is inherently capable of promoting a dramatic pH jump, resulting in a highly acidic environment that rapidly causes inactivation and kills at least 99.99% of the pathogens tested (including 3 drug-resistant bacteria such as MRSA, as well as SARS-CoV-2) in less 5 min. These methods afford effective and unexplored pathways to broad-spectrum anti-infective materials.

About the Speaker

Dr. Richard J. Spontak is a Distinguished Professor and Alumni Distinguished Graduate and Undergraduate Professor in the Departments of Chemical & Biomolecular Engineering and Materials Science & Engineering at North Carolina State University in Raleigh. He received his B.S. degree in Chemical Engineering (with honors/high distinction) from the Pennsylvania State University in 1983 and was later awarded the Ph.D. degree in Chemical Engineering from the University of California at Berkeley in 1988. He then pursued post-doctoral research in Materials Science & Metallurgy at the University of Cambridge (U.K.) and Condensed Matter Physics at the Institute for Energy Technology (Norway) before joining the Corporate Research Division of the Procter & Gamble Company in 1990. In 1992, he accepted a faculty position at North Carolina State University, where he supervises the Macromolecular Materials & Morphology Group. Since that time, Spontak has published over 290 peer-reviewed journal papers and over 35 scholarly works as book chapters and invited monographs, and his work has been featured on 30 journal covers and cited over 13,000 times according to Google Scholar. Although active in a diverse range of disciplines, his primary research interests relate to the phase behavior and morphology/property development of nanostructured polymers, polymer nanocomposites and coatings, electron microscopy, and stimuli-responsive soft materials. In recognition of his fundamental and applied research endeavors, he is the recipient of numerous honors and awards such as the Alcoa Foundation Engineering Achievement and Distinguished Engineering Research Awards, Alexander von Humboldt and Tewkesbury fellowships, the North Carolina State University Alumni Outstanding Research and Global Engagement Awards, the 2006 American Chemical Society (PMSE Division) Cooperative Research Award in Polymer Science & Engineering, the 2007 German Society for Electron Microscopy Ernst Ruska Prize, the 2008 American Chemical Society (Rubber Division) Chemistry of Thermoplastic Elastomers Award, the 2011 Institute of Materials, Minerals and Mining (IOM3) Colwyn Medal, the 2012 Norwegian University of Science & Technology Lars Onsager Medal, and the 2015 Society of Plastics Engineers International Award. An elected fellow of the American Physical Society, IOM3 and the Royal Society of Chemistry, he is or has been on the editorial advisory board of more than 20 international journals and holds editorial positions on 3 of them. He has been recognized as a 2007 Outstanding Scholar Alumnus and a 2012 Alumni Fellow by the Pennsylvania State University, and he is a member of the Norwegian Academy of Technological Sciences and the North Carolina State University Research Leadership, Global Engagement and Outstanding Teaching Academies. Spontak is also a highly acclaimed educator and academic mentor. For his instructional effectiveness employing cooperative and active learning pedagogies in the classroom and his widespread efforts to promote interdisciplinary engineering design and undergraduate research, he has received college- and alumni-level Outstanding Teaching Awards, as well as the university-level Board of Governor's Award for Excellence in Teaching, the highest institutional honor bestowed by the University of North Carolina system. He has also received the 2006 International Network for Engineering Education & Research Recognition Award and the 2009 American Society for Engineering Education Southeast Region Outstanding Mid-Career Teaching Award, and he has served as a Fulbright Senior Specialist and an Erasmus Fellow. He resides in Raleigh, North Carolina, with his wife Josie and has two children, Danielle and Joshua.