Abstract
Hydrogen peroxide is a cell signaling molecule and also a cytotoxic agent regulated by antioxidant enzymes. Hydrogen peroxide is involved in secondary cellular communications and in oxidative stress within cells. It promotes aging and age-related diseases such as cancers and Alzheimer's. Chemical sensors that are specific to hydrogen peroxide are used to locate and track the compound as it moves through the cell. Information regarding how hydrogen peroxide is produced and where it travels will provide insight into how it affects cell functions. Chemical sensors with boronic acids are selective to peroxides such as hydrogen peroxide and have been used in peroxide detection and bioimaging. A few new peroxide chemical sensors (Y1, Y2, Y3, Y4) were synthesized and the structures were verified by 1H NMR, 13C NMR, LCMS, and X-ray crystallographic analysis. UV/Vis and fluorescence titration experiments with hydrogen peroxide demonstrate a turn-on response as a result of the reaction between Y1, Y2, or Y3 sensors and hydrogen peroxide. Selectivity experiments confirmed Y3 sensor's abilities to react with peroxides such as hydrogen peroxide and TBHP as opposed to other common ROS. These novel chemical probes are useful tools to detect hydrogen peroxide in vitro. However, the sensors appear to not pass through the cell membrane to get into live human cells and thus are less likely to be used in live cell imaging applications. Y5, Y6, Y7, Y8, and Y10 were synthesized and the structures were verified by 1H and 13C NMR, UPLC-QTOF mass spectrometry, and X-ray crystallographic analysis. UV/Vis experiments using Y5 and Y6 and NMR experiments using Y5 suggest the compounds are unstable and degrade in aqueous environment and consequently can't be used as chemical sensors in aqueous solution nor for live cell imaging.