Aptamer-Based SERS Detection of Lysozyme on a Food-Handling Surface

Undeclared food allergens due to cross contamination of processing equipment is a leading cause for food product recalls. Therefore, there is a great need for developing rapid and sensitive methods to detect food allergens. In this paper, an aptamer highly specific to egg white lysozyme was coupled to dendritic silver nanoparticles in order to perform surface enhanced Raman spectroscopy (SERS). The procedure was successfully tested in water and on a stainless steel food-handling surface. The lowest detectable concentration for lysozyme was 0.5 g/mL in water and 5 g/mL on a stainless steel food-handling surface. Principal component analysis shows a significant change in SERS spectra when lysozyme was present, suggesting the successful capture of lysozyme by the aptamer. Quantification of lysozyme target was also shown from 0 to 6 g/mL, that is, 0, 0.5, 2, 6 g/mL. Overall method took less than 40 min. The developed method can be extended to detect other food allergens using specific aptamers. Practical Application We developed a simple, rapid, and sensitive method to detect an egg allergen on a food-handling surface by using aptamers (that is, artificially engineered single stranded DNA) as the capturer and surface enhanced Raman spectroscopy (SERS) as the detector. Our tests showed low concentration detection capability in the parts per million (ppm) level with minimal analysis time (that is, <40 min). This technique can potentially be used for rapid screening of food-handling surfaces to detect undeclared allergens.