Non-technical Abstract: Electrochemical sensing of ions has a critical role in various fields including clinical analysis, environmental monitoring, and industrial process control. One particularly important subgroup of electrochemical sensors are ion-selective electrodes (ISEs), which detect target ions by electrical signals. Although a variety of organic molecules have been used in ISEs as ion-carriers (known as "ionophores") to improve the selectivity in ion sensing, the scope of applications for these ionophore-based ISEs remains restricted due to the chemical limitations of the organic ionophores. The project led by Dr. Zhenqiang Wang at the University of South Dakota and Dr. Nathan Netzer at Peru State College addresses this challenge by integrating into the ISEs a family of complex host molecules as a new class of ionophores. These hosts exhibit highly unique and tunable chemical structures, making it feasible to achieve size-selective and predetermined ion sensing. This new approach not only significantly expands the scope of ISEs, but has the potential to transform the design of ionophore-based ISEs. This project contains a strong educational and outreach component that aims to promote science, technology, engineering, and mathematics (STEM) education among two specific groups of underrepresented student populations, namely, tribal college students and students from primarily undergraduate institutions (PUIs). Undergraduates at Peru State College, a small rural PUI in Peru, Nebraska, are part of the team to perform cutting-edge research in the field of electrochemical sensing. The team also plans to conduct chemistry workshops at regional tribal colleges and host tribal student-faculty pairs to perform summer research at the University of South Dakota.
Designing new ionophores in ISEs for the specific task of molecular ion sensing continues to present significant challenges. The new class of ionophores utilized in this project represents a unique family of synthetic receptors known as metal-organic supercontainers (MOSCs). The favorable chemical and structural characteristics of the MOSCs, including their compositional versatility, structural modularity, and multi-pore architecture distinguish them from other synthetic ionophores and provide unprecedented opportunities for functionalizing ISEs and engineering new electrochemical sensing applications. This two-year project focuses on three specific aims: 1) incorporation of MOSCs into various polymeric mixed-matrix membranes; 2) fundamental studies of MOSC integrated ISEs; 3) tuning the specificity of ISEs by incorporating target-specific MOSCs. By participating in this research activity, graduate students, and undergraduate researchers are exposed to a diverse set of experimental techniques ranging from materials synthesis and electrochemical analysis to device fabrication.
