Iron ions play a key role in many physiological processes, which can provide feedback for the evaluation of biological systems and environmental processes. New strategies for portable determination of Fe3+ therefore are still in urgent need. Here, through an in situ generation of prussian blue nanoparticles (PB NPs) in aqueous solution, we developed a bimodal method for photothermal and colorimetric detection of Fe3+. The sensing mechanism is based on the effective oxidation etching of Au-Cu core-shell nanocubes induced by Fe3+, accompanied by the in situ generation of PB NPs. It can be attributed to the specific reaction between ferrous ions (Fe2+) from the reduction of Fe3+ and potassium ferricyanide (K3[Fe(CN)6]) in the reaction solution. The in situ produced PB NPs show distinct bare-eye-detectable readouts with highly sensitive colorimetric and photothermal responses and thus can be used for Fe3+ determination. Such colorimetric change signals of characteristic absorbance at 740 nm in the UV-vis spectra showed a sensitive response to Fe3+ with a LOD of 210 nM. Moreover, as a sensitive photothermal probe, PB NPs generated in our Fe3+-enabled reaction system also exhibited a sensitive response to Fe3+ with a LOD of 70 nM. In addition, the standard addition experiments demonstrate our photothermal and colorimetric probe has good applicability for Fe3+ detection in the river water sample. What's more, the proposed strategy opens a new horizon for affordable detection of metal ions using a common thermometer, and therefore has a great potential for analytical chemistry and some important applications such as environmental monitoring, disease diagnostics and food analysis.

中文翻译：

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基于普鲁士蓝纳米粒子原位生成的环境样品中纳摩尔三价铁离子的光热和比色双模式检测

铁离子在许多生理过程中起着关键作用，可以为生物系统和环境过程的评价提供反馈。因此，仍然迫切需要便携式测定 Fe3+ 的新策略。在这里，通过在水溶液中原位生成普鲁士蓝纳米粒子 (PB NPs)，我们开发了一种双峰方法用于 Fe3+ 的光热和比色检测。传感机制基于 Fe3+ 诱导的 Au-Cu 核壳纳米立方体的有效氧化蚀刻，伴随着 PB NPs 的原位生成。这可以归因于反应溶液中Fe3+还原产生的亚铁离子(Fe2+)与铁氰化钾(K3[Fe(CN)6])之间的特定反应。原位生产的 PB NP 显示出明显的裸眼可检测读数，具有高度灵敏的色度和光热响应，因此可用于 Fe3+ 测定。紫外-可见光谱中 740 nm 处特征吸光度的比色变化信号显示对 Fe3+ 的敏感响应，LOD 为 210 nM。此外，作为一种灵敏的光热探针，在我们的 Fe3+ 启用反应系统中生成的 PB NP 也对 Fe3+ 表现出敏感的响应，LOD 为 70 nM。此外，加标实验表明我们的光热比色探针对河水样品中的Fe3+检测具有良好的适用性。更重要的是，所提出的策略为使用普通温度计检测金属离子开辟了新视野，