Hydride generation-based optical sensors have achieved on-site visual selenium (Se) determination with high anti-interference capability, yet they rely on the change of single-color intensity with a narrow linear dynamic range. Herein, we combined selenium hydride (H2Se)-induced activity inhibition of a manganese dioxide (MnO2) nanozyme with different degrees of 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation to realize sensitive multicolor visual detection of Se(IV). Due to its high oxidase-like (OXD-like) activity and sensitive response to H2Se, amorphous/crystalline manganese dioxide (ac-MnO2) was selected to form the headspace single droplet for microextraction and recognition. Via headspace redox reaction with H2Se, ac-MnO2 was reduced into low valence accompanied by in situ generation of Se nanoparticles, leading to the formation of a Se-MnOx aggregate. The experimental results and theoretical calculation indicated that, compared with MnO2, Se-MnOx had decreased active sites for adsorbing O2 to generate •O2–, resulting in the nanozyme activity inhibition that was totally dependent on Se(IV) concentration. The implementation of this strategy enabled accurate Se(IV) detection with a linear range from 10 to 600 μg L–1 and a limit of detection of 1.8 μg L–1. The portable smartphone-based detection for real sample analysis further demonstrated that this assay can be an easy, convenient, and intelligent tool for on-site selenium determination.
Luan Dongrui,Zhao Zengteng,Xia Dandan,Zheng Qiuling,Gao Xiaonan,Xu Kehua,Tang Bo
Sodium selenite has alleviating effects on liver fibrosis; however, its therapeutic molecular mechanism remains unclear. Herein, hydrogen selenide, a major metabolite of Na 2 SeO 3 , was tested to uncouple the sulfilimine bond in collagen IV, the biomarker of liver fibrosis. A mouse model of liver fibrosis was constructed via a CCl 4 -induced method, followed by the administration of 0.2 mg kg −1 Na 2 SeO 3 via gavage three times per week for 4 weeks. Changes in H 2 Se, NADPH, and H 2 O 2 levels were monitored in real time by using NIR-H 2 Se, DCI-MQ-NADPH, and H 2 O 2 probes in vivo , respectively. H 2 Se continuously accumulated in the liver throughout the Na 2 SeO 3 treatment period, but the levels of NADPH and H 2 O 2 decreased. The expression of collagen IV was analyzed through Western blot and liquid chromatography-mass spectrometry. Results confirmed that the sulfilimine bond of collagen IV in the fibrotic mouse livers could be broken by H 2 Se with the Na 2 SeO 3 treatment. Therefore, the therapeutic effect of Na 2 SeO 3 on liver fibrosis could be mainly attributed to H 2 Se that uncoupled the sulfilimine bond to induce collagen IV degradation. This study provided a reasonable explanation for the molecular mechanism of the in vivo function of Na 2 SeO 3 and the prevention of liver fibrosis by administering inorganic selenium.
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