Novel enzyme-linked immunoassay based on nanoceria as colorimetric substrate for foodborne pathogen detection

Rapid and reliable detection of foodborne pathogens is a key requirement for food safety. Traditional rapid ELISA methods assessed by the ability of horseradish peroxidase to oxidize a chromogenic substrate such as 3, 3′, 5, 5′-tetramethylbenzidine in the presence of H 2 O 2 may result in the high rate of negative responses because of the instability of H 2 O 2 and product. Here, we report the use of redox active nanoceria as colorimetric indicator in immunoassay taking Staphylococcus aureus as a model. The nanoceria is fully water-soluble and can be stored as least 90 days in the refrigerator while maintaining the same performance. Moreover, it does not require external H 2 O 2 , as glucose oxidase used in the immunoassay can catalyze the oxidation of glucose to produce H 2 O 2 in situ , which is more robust in signal readout. Taken together, these results demonstrate that nanoceria are potentially suitable as colorimetric substrate in the development of novel enzyme immunoassays.