DESCRIPTION): The objective of this proposal is to complete the development of a field-deployable, fully integrated device for the rapid and early diagnosis of cyanide poisoning in whole blood. The specific spectral shift of the vitamin B12 precursor cobinamide after binding cyanide will be used to measure the amount of cyanide in the sample. Cyanide is an extremely potent and rapid acting poison with as little as 50 mg fatal to humans. Currently there are no portable rapid tests for the detection of cyanide in whole blood available. However, emergency personnel and first responders have a need to measure the levels of cyanide in whole blood quickly on site in order to treat exposed individuals with an antidote and our test is intended to fill that niche. During feasibility, we demonstrated that we can detect low levels of cyanide in whole blood from rabbits with our concept device. We integrated the cobinamide chemistry into this prototype device by immobilizing modified cobinamide, cobinamide-polymer, on a membrane. To achieve that we had to develop a chemical modification through which the cobinamide retains its characteristic spectral shift when binding cyanide after it has been linked to a polymer. In our prototype device, whole blood was lysed, and then passed through the immobilized cobinamide-polymer, followed by a wash step. The spectral shift of cobinamide upon binding cyanide was measured with a handheld spectrophotometer. We now propose to complete the development of this prototype device into a fully functional and integrated test device. First, we will finalize all the assay components and optimize the chemistry for the test in order to maximize the analytical sensitivity. In parallel we will be developing a sample collection module that will enable us to reproducibly collect a measured amount of whole blood, lyse the red cells and deliver the sample to the test device. Once the device and the sample module have reached the prototype stage, we are initiating the development of a portable instrument which can interpret the test and provide the user with a concentration of cyanide in the sample. The prototype devices will be calibrated and then evaluated with samples from cyanide exposed rabbits and pigs, animal models that have documented success and have been accepted by the scientific and regulatory community. Production devices, sample collection modules and instruments will finally be extensively tested and validated. Validation studies for this Phase wil include the confirmation of sensitivity, specificity, accuracy, precision, and reproducibility and other studies that are typically required for FDA clearance. Clinical studies, including pivotal animal studies are outside the scope of this project and will be initiated upon completion of this Phase.