This project will use fluorescent organic salts to provide a new way for controlling photoexcited (i.e., activated by light) interactions at the cellular level. The principal investigator seeks to improve fluorescent dyes to limit toxicity for application to cell imaging and photodynamic therapy (PDT). The approach will develop a range of organic salts, assess phototoxicity (i.e., toxicity due to light) and then evaluate the chosen contrast agents. Improved imaging agents will be broadly useful and preliminary data suggest a reduction in phototoxicity. The research can lead to novel fluorescent probes for broad societal impact ranging from biomedicine and diagnostics to solar cells by enabling selective photodynamic therapy without side effects; brighter medical imaging that penetrate deeper into tissue for tumor detection and image-guided surgery.

The principal investigator utilizes a new approach that will pair fluorescent ions with non-fluorescent counterions to independently modulate frontier molecular orbital levels proposed to be responsible for cyto- and photo-toxicity, without modifying optical properties. The principal investigator proposes that the fine-tuning concept can be applied to both novel and commercially available fluorescent probes and will enable precise toxicity modulation of fluorescent probes in eukaryotic cells for a range of applications. The principal investigator will systematically engineer a series of ions that tune optoelectronic properties of fluorescent organic salts by modulating the degree of halogenation, steric bulk, and dipole moments. The central hypothesis will test if fluorescent organic salts provide cytotoxic and phototoxic tunability through counterion coupling by generating resonant reactive oxygen species via charge injection in cellular environments.

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.

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Michigan State University
East Lansing
United States
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