19F MRI, has shown promising success in clinical trials for monitoring cell therapy, where small groups of cells, showing poor contrast in 1H-MRI (Magnetic Resonance Imaging), are easily tracked using 19F-MRI.1 Contrast is provided by nanoemulsions of perfluorocarbon (PFC) oils pre-loaded into cells. A major advantage of 19F-MRI is that lack of natural fluorine in the body allows for very high contrast-to-noise for 19F-MRI compared to 1H-MRI.2 Use of 19F-MRI in molecular imaging, by targeting specific biomarkers, is of great interest, but the development of probes for these applications has been an elusive goal. Typical synthetic methods produce relatively large particles, > 150 nm, which induce nonspecific uptake by phagocytic cells. While avid nonspecific uptake is advantageous for labeling T cells and other immune cells ex vivo, it is a decided limitation for imaging of biomarkers as it can create high background signal in the inflamed tissues characteristic in many diseases. 19F MRI should be an excellent platform for biomarker detection but there is a critical unmet need for suitable 19F MRI contrast agents that avoid nonspecific immune cell surveillance. Ideally, contrast agents need to be<100 nm to avoid nonspecific uptake. We propose exploratory studies to develop innovative new 19F MRI contrast agents based on nanodiscs. Nanodiscs are < 50 nm in size, avoid liver clearance, and escape immune surveillance. We hypothesize that nanodiscs, which are structurally similar to high density lipoproteins that carry cholesterol in a hydrophobic core, may be ideal for carrying hydrophobic perfluorocarbons. Our aims are to explore synthetic parameters in benchtop (Aim 1) and microfluidic (Aim 2) approaches to optimize loading of perfluorocarbons into nanodiscs. In each aim we will systematically investigate variables that influence nanodisc size and perfluorocarbon loading. New nanodiscs will be characterized for physical properties such composition and dimensions, and the top 3 products from each Aim will be evaluated for lack of toxicity and biodistribution in a mouse model. The leading nanodiscs will be modified for targeting CD204, a biomarker for tumor associated macrophages, and tested in a mouse breast cancer model. We are team composed of contrast agent (UCD) and nanodisc (LLNL) experts who are ideally positioned and well-equipped to carry out the proposed aims. The success of this project would add novel nanodiscs materials with the potential not only for targeted 19F MR molecular imaging, but for applications in photoacoustic, and radiotherapy, and tracking drug delivery.