Aptamer-mediated charge neutralization and aggregation of gold nanorods for fast visual monitoring of di(2-ethylhexyl) phthalate in foods and its release from PET containers.

Di(2-ethylhexyl) phthalate (DEHP) is an emerging endocrine-disrupting contaminant, and its rapid monitoring in food is critically important. We developed an aptamer-induced charge neutralization and aggregation of gold nanorods (AuNRs) strategy for facile detection of DEHP. The negatively charged aptamers were adsorbed onto positively charged AuNRs, causing aggregation of AuNRs with color shift from wine-red to blue-gray. In the presence of DEHP, the aptamer binds to DEHP, suppressing aggregation and maintaining the dispersed state. This strategy achieved a detection limit of 4.2 nM, well below the drinking water limit set by the United States Environmental Protection Agency (EPA). The system was successfully applied for detection of DEHP in ten food samples and monitoring the DEHP release from PET containers. No DEHP was detected for hot water in disposable cups, bowls, etc., but PET bottles released over limit DEHP after cycles of reheating. This platform is promising for rapid monitoring of DEHP in food and its release from containers.