Boron-Rich Cluster Materials for Vibrational- and Mass Spectral-Based Bioimaging of Reactive Oxygen/Nitrogen Species

Project Summary Boron-Rich Cluster Materials for Vibrational- and Mass Spectral-Based Bioimaging of Reactive Oxygen/ Nitrogen Species Reactive oxygen and nitrogen species (ROS/RNS) are redox signaling agents that underpin a myriad of important biological processes but are also sources of oxidative stress and damage. Their misregulation is implicated in neurodegenerative, autoimmune, and cardiovascular diseases. Activity-based fluorescent sensors, which use chemical reactivity to track distinct ROS/RNS, are often deployed to evaluate redox regulation in biology. However, the broad absorption and emission profiles inherent to fluorescent readouts is a limitation when attempting to study multiple processes simultaneously via multiplex bioimaging. Bioimaging approaches based on vibrational spectroscopy or mass spectrometry, such as Raman and time-of-flight secondary ion mass spectrometry (ToF-SIMS), are emerging as attractive alternatives to fluorescent imaging. The detection of narrow signatures inherent to vibrational readouts in Raman, and the detection of ions in ToF-SIMS, surpasses the multiplexing capabilities of fluorescence techniques. However, there do not exist activity-based sensors amenable to these imaging approaches despite considerable progress in the availability of commercial instrumentation. Thus, the long-term goal of this project is to develop boron-rich cluster imaging agents capable of monitoring an array of distinct ROS/RNS via activity-based sensing (ABS) in a broad range of biological models across both vibrational and ToF-SIMS bioimaging modalities. Boron-rich cluster compounds are underexplored in the context of bioimaging. However, their unique electronic and physiologically benign properties can enable them to serve as sensors for emergent imaging technologies. The B-H bonds on these cluster species exhibit a stretching frequency that appears in a silent region in the vibrational spectra of biological samples. Additionally, the efficient ionization of boron-rich clusters and distinct 11B isotope signature enables their application in ToF-SIMS imaging. First, we will synthesize a panel of ROS/RNS responsive and cell trappable boron-rich cluster sensors and evaluate their selectivity for distinct ROS/RNS. Second, we will apply our sensors to monitor ROS/RNS localization in ToF-SIMS bioimaging experiments of mammalian cell models of oxidative/nitrosative stress. In collaboration with RPL#1, we will translate our sensor platform to single cell and tissue scale investigations of ROS/RNS involvement in chronic and neuropathic pain. The third aim involves applying our developed sensors to obtain quantitative and spatial information on ROS/RNS fluxes in Raman bioimaging experiments in mammalian cell models of oxidative/nitrosative stress. In collaboration RPL#5, we will deploy our sensor platform to monitor and quantify ROS/RNS effects in vasculogenesis and angiogenesis. Our boron cluster ABS imaging agents will complement both fundamental and translational chemical biology research by enabling us to further elucidate ROS/RNS-mediated communication across a broad range of clinically relevant biological models.