A dual-mode colorimetric and fluorometric sensor for the detection of spermine and spermidine in food based on N-doped carbon dots and peroxidase-like activity of V6O13 nanobelts

Spermine (SPM) and spermidine (SPD) exist widely in food, and their excessive consumption will cause serious harm to human body, so it is significant that determine the content of them in foods. Herein, the peroxidase-like activity of V6O13 nanobelts could catalyze n-ethyl-N-(3-sulfopropyl)-3-methylaniline sodium salt (TOPS) and 4-amino-antipyrine (4-AAP) to generate the purple complex (PC1). It was first found that PC1 could quench the CDs fluorescence by static quenching (SQE). The SPM and SPD can inhibit the peroxidase-like activity of V6O13, making changes in the color and fluorescence intensity of the solution. Therefore, a fluorescent and colorimetric dual-mode sensor were constructed. The quantitative analysis of SPM and SPD will be realized through the variation of dual signal. Such sensor offers good detection sensitivity for SPM and SPD. The limit of detection (LOD) of SPM and SPD on colorimetric channel were 3.42μg·L-1 and 11.10μg·L-1, separately. In the fluorescent channels, the LOD of SPM and SPD were individually determined as low as 1.16μg·L-1 and 1.31μg·L-1. Particularly, the results of the dual-channel could be mutually validated, which improved the reliability of the assay. Such method demonstrated good detection of SPM and SPD in actual samples, indicating its huge potential for practical application.