Selective sensors are very useful for on-site and real-time detection of adulterants or contaminants in food safety and quality. Despite a lot of effort, few such sensors are commercially available, especially for metal ions and organic toxins. We have identified challenges in both fundamental science and in technological development, and have made significant progresses in meeting these challenges. In fundamental science, designing sensors based on a single class of molecules for a broad range of targets is a major challenge. Most processes are based on a trial and error where successes in designing sensors for one target can be difficult to translate success in designing sensors for other targets. To meet these challenges, we have used in vitro selection or SELEX to obtain DNAzymes, a class of metalloenzymes that use DNA molecules exclusively for catalysis, and DNA aptamers, a class of nucleic acids that rival antibodies in binding targets of choice strongly and specifically, and used negative selection strategy to improve the selectivity. By labeling the resulting DNAzymes and aptamers with fluorophore/quenchers, gold nanoparticles, and quantum dots, we have developed new classes of fluorescent and colorimetric sensors for metal ions and a wide range of other targets with high sensitivity (down to 14 pM) and selectivity (&gt; 1 million fold selectivity).1 For example, we recently has taken advantage of size-dependent modulation of graphene oxide-aptamer interaction for amplified fluorescent detection of aflatoxin B1 with tunable dynamic ranges.2 In technological development, there are still significant barriers for the public to adopt new devices or technologies developed in labs. We are exploring ways to overcome this barrier by taking advantages of the wide availability and low cost of the pocket-sized electrochemical devices such as glucose meters to detect many non-glucose targets,3 including those in food safety and quality, such as melamine and Ochratoxin A.4 Since in vitro selection can be used to obtain DNAzymes and DNA aptamers to bind a wide range of targets, this approach can be readily used by the general public to detect many other targets in food safety and quality.

DNAzyme- and DNA aptamer-based nanosensors for on-site and real-time detection in food safety and quality

254th National Meeting (2017)

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