Alzheimer's disease (AD) is a major cause of disability and death. Many drugs are being developed to try to slow the deterioration in AD, thus early diagnosis will be essential in order to start treatment before brain function is irretrievably lost. We aim to provide a novel, non-invasive method for early diagnosis of AD. A radioactive positron emission tomography (PET) imaging reagent that binds amyloid plaques was recently approved for clinical use, but it suffers from high cost and limited availability. We will develop iron nanoparticles that can enter the brain and specifically bind to amyloid plaques for detection by MRI, a more affordable and accessible technique. The particles consist of a core of iron oxide coated with materials to bind plaques, protect particles, and enhance brain uptake. We demonstrated that these materials can reach the brain and bind plaques, and iron particles are used currently in people for several MRI applications. Our experience with nanoparticles in an AD animal model in our previous work will facilitate accomplishment of this proposal. The success of this project will enable clinicians to identify potential AD patients early in the disease, when the many currently-tested treatments, if they work, may preserve the patient's ability to function independently, thus extending the duration of healthy life and greatly reducing burden on caregivers and cost to health care systems.