NSF Award
2102581
In this project, funded by the Chemical Structure, Dynamics & Mechanisms-B Program of the Chemistry Division, Professor Pavel Anzenbacher at Bowling Green State University seeks to understand which molecular features govern the recognition and sensing of phosphate-related anions and their simultaneous detection in water. Phosphate-related anions are of great importance in biology, industry, and agriculture but their analysis in aqueous environments remains challenging because of inefficient binding and sensing of anions in water by artificial receptors and sensors. Most current methods focus on sensing of phosphates in their pure form, without other competing phosphate-type anions. This project endeavors to develop new types of supramolecular anion sensors that show fluorescence amplification in the presence of phosphate-type anions. These new sensors are designed to address the long-standing challenge of identifying and quantitating phosphate anions of environmental and/or biological significance in mixtures of closely related anions. The proposed sensors are comprised of two components: phosphate receptors and a fluorescent dye that changes fluorescence in the presence of phosphate. These two moieties are connected in such a way that enables the binding of a range of phosphate anions while producing a different fluorescence output signal. The information on phosphate-type anion sensing will likely contribute to the development of new inexpensive and widely applicable sensors for phosphates and phosphonates. This project has the potential to advance knowledge required, for example, to develop more effective environmental sensing platforms or sensing-based biotechnologies such as the real-time quantitative polymerase chain reaction (qPCR). This research provides opportunities for multi-disciplinary education in organic chemistry and photochemistry, as well as supramolecular chemistry. The environmental sensing aspects and utility of the sensors in polymerase chain reaction (PCR) will provide for a multi-faceted education for students and encourage interdisciplinary thinking. Undergraduate students will be mentored by the PI within the framework of the activities of the Center for Undergraduate Research and Scholarship (CURS) program. CURS aims to enhance undergraduate education through active participation in research. The PI also acts as a mentor in the Parents Involvement with Children Nurturing Intellectual Curiosity in Science (PICNICS) program, designed to expose high school students to research in chemistry and stimulate their interest in science. <br/><br/>The impact of anions in biology, industry, and agriculture is broad and requires the development of new and practical sensing concepts for such species. Unfortunately, the binding and sensing of anions in water by artificial receptors and sensors is inefficient. This proposal seeks to increase understanding of the molecular features that govern the recognition and sensing of phosphate-related anions and their simultaneous detection in water. Most current studies describe the sensing of phosphates in their pure form, without other competing phosphate-type anions. The project aims to address a long-standing problem: the determination of identity and quantification of phosphate anions of environmental and/or biological significance in the mixtures of closely related anions. Thus, the goal of this project is to develop cross-reactive supramolecular sensors based on receptor-dye ensembles to sense phosphate type anions. The proposed sensors are comprised of two components: (i) a bifunctional receptor comprising a metal binding site such as a dipicolylamine-Zn(II), Co(II), etc. and arylboronic acid connected via a variable-length spacer, and (ii) a fluorescent dye capable of binding both moieties of the receptor. The principle of operation is as follows: The metal complex of the receptors coordinates fluorophores to form a non-fluorescent sensor ensemble. Binding of target phosphates to the receptor ejects the fluorophore from the quenching metal site, which then forms an ester with boronic acid. The complex of the fluorophore with boronic acid is brightly fluorescent, resulting in a dramatic increase (turn-ON) of fluorescence. Recorded sensing data will be processed using pattern recognition methods (linear discriminant and principal component analysis). Quantitative analyses will be performed using linear regression algorithms. Further studies using artificial neural network (ANN) and support vector machines (SVM) algorithms will be performed to improve the performance of the sensors with respect to limits of detection, dynamic range, linearity, etc. The target anions will be phosphorus-based eutrophication agents and herbicide phosphonates such as glyphosate (also known as RoundUp™) in the presence of competing electrolytes. This new sensing method will also be utilized in sensing of biological phosphates (pyrophosphate and nucleotide triphosphates) for application in biosensing and related technologies including PCR.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
