Mycotoxins are toxic compounds produced by fungi that contaminate crops during growth, transportation, or storage. Contamination of food and feed by mycotoxigenic fungi is an important agricultural and national security concern. For example, thousands of people are sickened annually by mycotoxicoses related to crops contaminated with fungi, and the safety of the food supply is integral to our national health and security. All of these issues demand the development of improved toxin sensor technologies. Current mycotoxin detection methods (e.g., those based on antibodies) have practical shortcomings both in the development of the sensors and in their applications. In this Phase I STTR, we will develop innovative mycotoxin sensors based on allosteric DNAzymes, which are catalytic DNA molecules that are activated by binding of an analyte such as a mycotoxin. The long-term commercial objective of this project is to develop quantitative mycotoxin sensors for precise assays and also to develop semi-quantitative mycotoxin sensors for rapid field assays. This Phase I research will be performed with three specific aims: (1) Apply in vitro selection to identify allosteric DNAzymes that have high selectivity and sensitivity to the mycotoxin deoxynivalenol (DON) and other mycotoxins such as fumonisin B1, zearalenone (ZON), and aflatoxin B1; (2) Characterize and optimize the allosteric DNAzymes for toxin-sensing properties; and (3) Engineer fluorimetric or colorimetric mycotoxin sensors by integrating fluorophore or gold nanoparticle detection systems with the DNAzymes identified in Aims 1-2. In Phase II of the project, the allosteric DNAzyme sensors will be tested in the field to determine their absolute and relative efficacies as toxin detectors. This includes integration of the DNAzyme sensors with the standard storage and transport aeration system used in grain containment units, which will increase the assay sensitivities by concentrating analytical samples. Relevance to public health: Contamination of food and feed by mycotoxin-producing fungi is one of the most important health-related problems in the US and worldwide. Improved sensors for detecting mycotoxins and thereby revealing the presence of fungi will allow proper remedial actions to be taken. [unreadable] [unreadable] [unreadable]