Abstract Alzheimer's disease (AD) and other age-related neurodegenerative disorders have become a global health and social challenge. Although the exact cause of AD is still under investigation, among various AD hypotheses, oxidative stress is considered either a causative factor or a critical cofactor in cascades of events leading to neuron death. Because of the importance of oxidative stress in the etiology and pathogenesis of AD, research tools that can conveniently evaluate oxidative stress in AD models are expected to greatly catalyze and accelerate research on AD. The overall objective of this R01 project is to develop and optimize genetically encoded fluorescent redox indicators (GERIs) for the convenient evaluation of oxidative stress in AD mouse models. This project uses the synergy of two productive investigators at the University of Virginia (UVA). Huiwang Ai (Ph.D., PI) has expertise in genetically encoded fluorescent indicators and fluorescence imaging of redox signaling in live cells and animals. Heather Ferris (M.D./Ph.D., Co-I) is a physician-scientist with a research focus on metabolic drivers in AD and other cognitive disorders. Leveraging our complementary expertise and strong preliminary results, we will develop and optimize GERIs for intensity-based ratiometric (Aim 1) and lifetime (Aim 2) imaging. We hypothesize that the GERIs can be used to conveniently assess oxidative stress status in AD mouse models during disease progression and in response to therapies, and we will test this hypothesis in Aim 3. The proposed research will lead to a toolbox of GERIs for quantitative imaging of oxidative stress in animal models. These innovative tools will allow precise measurement of specific redox parameters in specific cell types and subcellular domains, facilitating our understanding of AD mechanisms and further intervention development. Although the focus of the current phase of this project is on technology development and validation, we expect our study will catalyze an extensive array of biological studies on ROS and oxidative stress in the brain, resulting in a tremendous amplification of the impact of this project.