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-MnO_x aggregate. The experimental results and theoretical calculation indicated that, compared with MnO₂, Se-MnO_x 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.

中文翻译：

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氢化硒诱导的无定形/结晶二氧化锰氧化酶样活性抑制：硒检测的比色法


基于氢化物发生的光学传感器实现了现场视觉硒 （Se） 测定，具有很高的抗干扰能力，但它们依赖于具有较窄线性动态范围的单色强度的变化。在此，我们将氢化硒 （H₂Se） 诱导的二氧化锰 （MnO₂） 纳米酶活性抑制与不同程度的 3,3′，5,5′-四甲基联苯胺 （TMB） 氧化相结合，实现灵敏的多色视觉检测 Se（IV）。由于其高氧化酶样 （OXD-like） 活性和对 H₂Se 的敏感反应，选择无定形/结晶二氧化锰 （ac-MnO₂） 形成顶空单液滴，用于微提取和识别。通过与 H₂Se 的顶空氧化还原反应，ac-MnO ₂ 被还原成低价，同时原位生成 Se 纳米颗粒，导致 Se-MnO_x 聚集体的形成。实验结果和理论计算表明，与 MnO₂ 相比，Se-MnO_x 吸附 O₂ 生成 ^•O₂^– 的活性位点降低，导致纳米酶活性抑制完全依赖于 Se（IV） 浓度。该策略的实施实现了准确的 Se（IV） 检测，线性范围为 10 至 600 μg L^–1，检测限为 1.8 μg L^–1。用于真实样品分析的基于智能手机的便携式检测进一步表明，该检测可以成为一种简单、方便和智能的现场硒测定工具。