Highly sensitive “signal on” plasmonic ELISA for small molecules by the naked eye

Abstract

Based on the H₂O₂-mediated generation of gold nanoparticles, a colorimetric catalase nanosensor was developed and utilized as a signal output in a catalase-labelled immunoassay. Methyltestosterone (MT), which is used illegally as a growth promoter during the cattle production cycle, was selected as a small molecule model in this new ELISA development. As a result, a “signal on” plasmonic ELISA for MT was established. This plasmonic ELISA can quantitatively detect MT by spectrophotometry with a 50 times higher sensitivity than the traditional ELISA. In addition, it allows the highly sensitive and easily qualitative detection of MT by the naked eye. This plasmonic direct competitive ELISA can be utilized for developing cost-effective and sensitive ELISA against various small molecules by the naked eye.