NSF Award
2203640
With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Davita L. Watkins of the University of Mississippi is developing polymeric systems that can encapsulate biocompatible organic fluorophores for fluorescence imaging. Fluorophores are dyes that contain special carbon-carbon double bonds called pi-bonds. When these pi-bonds are irradiated with light of a certain wavelength, it enables the fluorophores to re-emit that light but with a different wavelength and much higher intensity. This unique characteristic makes them particularly useful for bioimaging applications. In this research, biocompatible amphiphilic polymers containing both water-loving (hydrophilic) and oil-loving (lipophilic) segments will first be prepared. Their amphiphilic properties resemble those of other artificial compounds such as soaps and detergents, or even naturally occurring lipoproteins. Synthesized polymers will then be assembled to create well-defined nanosized capsules which are capable to trap fluorophores. Various dynamic processes that will occur during polymer assembly and encapsulation will be studied using several spectroscopic techniques. Results associated with this research have the potential to advance the field of bioimaging and further understanding of optical properties of fluorophores in nanoconfined environments. This work is a multi-disciplinary study in which fundamental aspects of development will provide fertile ground for the training of early career scientists and offer design guidelines toward functional polymeric materials. Specific outreach endeavors will focus on research activities for transfer students and/or students having nontraditional academic paths as they make up a significant portion of the collegiate population in the state of Mississippi. The research will equip the next generation of scientists with the skills, collaborative spirit, and creativity to solve complex societal problems. A diverse scholastic population will also become more exposed to the emerging and dynamic area of fluorescence imaging, preparing them to contribute to an expanding STEM (science, technology, engineering and mathematics) workforce. <br/><br/>This research will develop new approaches to biocompatible organic fluorophores for fluorescence imaging. Specific emphasis will be placed on developing linear-dendritic block copolymers and dye-polymer conjugates with optical properties in the second near-infrared window (NIR-II, 1000–1400 nm), which has emerged as a high-priority in recent years due to poor stability and biocompatibility of current agents. By employing amphiphilic substrates, the fundamental mechanism of self-assembly that results in well-defined, uniform nanostructures ideal for fluorescence imaging will be elucidated. From the point of view of macromolecular design, linear-dendritic block copolymers will be synthesized with hydrophobic blocks consisting of polyesters such as polylactides and polycaprolactones. Hydrophilic dendritic branches will be composed of polyamidoamines. NIR-II fluorescent dyes with aggregation-induced emissive molecular frameworks capable of self-assembling into monodisperse micellar structures will be strategically designed with thienothiadiazole and thienoselenadiazole units as the core acceptor structures. This research is cross-cutting with relevance to principles of organic and physical chemistry, and materials science. The work has the potential to contribute to bio-imaging development by providing a deeper understanding of unconventional related photophysical phenomena.<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.
