Selenium as a brightening agent for peroxidase-like activity regulation of MXene@CeO₂ sensing platform

Selenium is a nutritionally essential trace element for human health, but efficient or excessive intake both causes physiological diseases. Here, we propose that selenium as a brightening agent significantly increase the peroxidase (POD)-like activity of MXene@CeO₂, which CeO₂ nanoparticles in-situ grow on MXene as the sensing platform. Based on the selenium-stimulated POD-like activity of MXene@CeO₂, a simple, low-cost, and reliable colorimetric method is constructed for quantitative analysis of selenium. The great advantage of MXene@CeO₂ platform selecting selenium as brightening agent exhibits good selectivity for other 23 interfering ions, allowing the discrimination of selenium in practical samples rapidly and precisely even at 3.5 nM. Moreover, MXene@CeO₂ platform selectively catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) instead of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium (ABTS) under the same condition. This study not only offers a utility sensing platform for quick detection of selenium but also opens an avenue for the rational design of element sensors for point-of-care application.