DNA Nanotechnology: Developing and Analyzing a New Tool for Sensing Allergens

Abstract

Allergens are a major problem especially concerning public health and economy. There are more than 150 foods that can initiate allergic reactions, these reactions can elicit a mild response or a dangerous life threatening condition and in some extreme cases death. Milk and milk ingredients are one of the 8 foods that are responsible for about 90% of all food related allergic reactions. Food containing undeclared allergens in the label are misbranded and adulterated, and in accordance with the FSMA law must be recalled. It is estimated that the food industry can spend up to $10 millions dollars in direct costs from a recall. It was hypothesized that aptamer-amphiphile, a synthesis product from ssDNA aptamer and a hydrocarbon tale, in conjunction with liquid-crystal could be used as a sensor for detection of -lactoglobulin, an allergenic whey protein. The sensor was based on the self-alignment properties of liquid crystals based on the environment that it is exposed and on the capabilities of DNA aptamers to specific binding to targets. Results of this work showed that the aptamer-amphiphile of choice, amphiphile synthesized without a spacer between the DNA head group and the hydrocabon tail, had a great affinity to target, Kd= 45 ± 1.68 nM. In addition to it, it was possible to demonstrate that the interaction of the aptamer-amphiphile with the target protein, -lactoglobulin, using the sensor assembly resulted in images that can be easily identified under the polarizing microscope, sensor exposed to the aptamer-amphiphile alone gave a black image, once the protein was introduced the image was bright. Furthermore, the sensor developed has a limit of detection of 18.4ng of -lactoglobulin. It was also able to selectively identify the target protein, since when aptamer-amphiphile supported on the sensor was exposed to a random protein the image did not change as it did with -lactoglobulin. In conclusion, this sensor developed proves the concept that aptamer-amphiphile and the liquid crystal can potentially be used as a sensor technique in food plants to detect allergens in food contact surfaces.