The Nutbrown group researches fluorescent sensors that can act as tools in alleviating tangible societal issues.

Fluorescent probes for Li+

Lithium salts have been prescribed as the gold standard treatment for bipolar disorder for fifty years, continuing to outperform newer, alternative mood stabilizers. Despite this longevity, the pharmacological mode of action for Li+ in treating bipolar disorder is still speculative. A common theme among most theories is competition between Li+ and Mg2+ for binding sites in enzymes. Probing this dynamic has been difficult, however, as researchers lack a sensitive and specific tool for tracking Li+ in cells. Therefore, the overall goal of this project is to develop a Li+-specific fluorescent probe for use in cells to investigate the biochemical role of lithium salts in the treatment of bipolar disorder.

Toward this end, undergraduate researchers are synthesizing ligands with the potential to act as Li+-specific fluorescent sensors. The metal ion-binding properties of these ligands are being tested in solution to assess their ability to selectively sense Li+ at therapeutically relevant concentrations. Successful fluorescent probes will be used to measure Li+ levels in vivo using fluorescence microscopy. Ultimately, a Li+-specific probe will aid researchers in fully understanding the chemical imbalance behind bipolar disorder and designing more effective drugs to treat it.

The journal cover on the left illustrates a metallacrown Li+ sensor reported by Rochat, Grote, and Severin in 2009.

Ethylene sensors based on Ag(I)-bound fluorescent molecules

Ethylene is the plant hormone responsible for the phenomenon of "one bad apple spoiling the whole bunch." In excess, this simple gaseous molecule is responsible for the loss of millions of dollars of produce post-harvest annually. A sensitive, real-time, cost-effective sensor could be coupled with an ethylene removal system to regulate the ripening hormone's presence in storage and transport units for foodstuffs. The sensing strategy applied by Nutbrown group members involves using a coinage metal ion, such as Ag(I), attached to a fluorescent molecule. The metal ion acts as a signal transducer by changing how it interacts with the fluorescent ligand when ethylene binds. The emission intensity of the fluorescent ligand changes as a result of this sensing event.