CHEE Seminar: Jinsang Kim
Monday, November 27, 2023 – 3:00 p.m.
Jinsang Kim, PhD
Professor and Director, Materials Science and Engineering
Professor, Macromolecular Science and Engineering, Chemical Engineering, Biomedical Engineering and Chemistry
University of Michigan
"Rational Molecular Design of Organic Functional Materials for Biosensors and Optoelectronics"
Speech & Hearing Building, Room 205
Social Hour immediately following the seminar in Old Engineering 157 (Graduate Student Lounge) at 4:00 p.m.
ABSTRACT
Conjugated polymers (CPs) and organic molecules have become emerging materials for many modern technologies due to their readily tunable properties by variation of chemical structure and easy fabrication. Particularly the sensor application of CPs has gained much interest recently because CP-based sensors can provide large signal amplification. Our self-signaling optical sensors are designed to achieve high sensitivity by means of the external stress-responsive optical property of conjugated polymers. Receptors are rationally designed to provide specificity toward a target analyte to realize high selectivity. We have developed conjugated polymer-based optical sensory systems to detect various target molecules such as DNA, proteins, metal ions, influenza virus, antibiotics, prostate specific antigen, nerve agents, and melanin. The concept, design principles, and applications of CPs for self-signaling sensors and sensor arrays will be discussed.
Novel sensory systems based on metal-free purely organic phosphors will also be presented. In our recent development of highly emissive and metal-free purely organic phosphorescence materials for the last decade, directed intermolecular heavy atom effects were rationally implemented in aromatic carbonyl molecules to promote spin-orbit coupling and suppress vibrational dissipation. Color tuning by electron density modulation was successfully implemented in the metal-free purely organic phosphors (POPs). Due to rather slow electron spin flipping during phosphorescence emission of POPs, molecular engineering to prevent collisional energy dissipation turned out to be critical to achieve bright phosphorescence emission in ambient conditions. On the other hand, the same slow phosphorescence feature renders highly sensitive oxygen quenching via energy transfer from POP’s triplet state to surrounding oxygen molecules in the ground state. This unique phenomenon has been utilized in a newly devised lipid-polymer hybrid POP turn-on nanoprobe for chorioretinal hypoxia detection in vivo using rabbit retinal vein occlusion and choroidal vascular occlusion models.
BIOSKETCH
Jinsang Kim is a professor and director of macromolecular science and engineering, and a professor of materials science and engineering having a joint appointment in chemical engineering, biomedical engineering and chemistry at the University of Michigan, Ann Arbor. He holds an MS (1993) and a BS (1991) from Seoul National University, Korea, both in fiber and polymer science. He earned his Ph.D. in 2001 in materials science and engineering from MIT (Advisor Prof. Tim Swager), where he studied the design, synthesis, and assembly of conjugated sensory polymers and energy transport properties in controlled structures. He is also an expert in genetically engineered protein research. His postdoctoral work in this area at Caltech (Advisor Prof. David Tirrell) involved the expression of artificial genes to determine the extent to which artificial genetic information can be used to encode supramolecular assembly in macromolecular systems.