Here, we report ion-selective nanospheres with readout in the near-infrared (NIR) region in both fluorescence and absorbance modes. The nanospheres rely on an ionophore-mediated monomer-dimer conversion of an NIR transducer, DTTC. The DTTC monomer in the nanospheres emits fluorescence around 820 nm, while the dimer in the aqueous environment generates strong blue-shifted emission around 660 nm. With a lead ionophore, an unprecedented lower detection limit of 3 pM for Pb²⁺ was achieved, allowing us to determine Pb²⁺ levels in river water without diluting the sample. Also, the Cu²⁺-selective nanospheres showed a detection limit of 5 nM. Taking advantage of the biologically desired NIR window, blood potassium concentrations were also determined without a complicated sample pretreatment. The sensing process was explained with a theoretical model. The detection range was found finely adjustable by the amount of nanospheres used. Therefore, the nanospheres formed a highly selective, sensitive, versatile, and rapid analytical platform for metal-ion sensing.

中文翻译：

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在近红外区域基于单体-二聚体转化的基于离子载体的离子选择性纳米球

在这里，我们报告在荧光和吸收模式下在近红外（NIR）区域具有读数的离子选择性纳米球。纳米球依赖于NIR换能器DTTC的离子载体介导的单体二聚体转化。纳米球中的DTTC单体在820 nm附近发射荧光，而水性环境中的二聚体在660 nm附近产生强烈的蓝移发射。使用铅离子载体，实现了Pb ²⁺前所未有的3 pM的较低检测限，这使我们能够在不稀释样品的情况下测定河水中的Pb ²⁺含量。另外，Cu ²⁺选择性纳米球的检测极限为5 nM。利用生物学上所需的NIR窗口，无需复杂的样品预处理即可测定血钾浓度。用理论模型解释了感测过程。发现检测范围可以根据所用纳米球的数量进行微调。因此，纳米球形成了用于金属离子感测的高度选择性，灵敏，通用和快速的分析平台。