Quantum dots (QDs) have been widely used to develop analytical methods due to their unique fluorescent and photoelectrochemical characteristics. However, analytical strategies based on their catalytic property are rarely reported. Here, we demonstrate that the photoreductive ability of QDs can be utilized to develop a sensitive and selective colorimetric sensor for Cu(II). By using UV irradiation, 3,3',5,5'-tetramethylbenzidine (TMB) is oxidized to its oxidation product, which can be reduced back to TMB by QDs. The presence of Cu(II) decreases the reductive activity of QDs and results in a color change in a signal-on format. The proposed sensor can be activated using a portable UV lamp or direct sunlight. Under optimized conditions, the detection limit (S/N = 3) is 10 nM via spectrophotometry and 0.1 μM by visible color change. This sensing system was applied to quantify Cu(II) in real samples, such as river water and tap water. Results were in agreement with those obtained using inductively coupled plasma spectrometry (ICP). This study may provide new ideas for the development of QD-based sensors.

中文翻译：

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基于量子点光还原能力的用于 Cu(II) 可见光检测的新型比色传感器

量子点 (QD) 由于其独特的荧光和光电化学特性而被广泛用于开发分析方法。然而，很少报道基于其催化性能的分析策略。在这里，我们证明了 QD 的光还原能力可用于开发用于 Cu(II) 的灵敏且选择性的比色传感器。通过使用紫外线照射，3,3',5,5'-四甲基联苯胺 (TMB) 被氧化为其氧化产物，该产物可以通过 QD 还原回 TMB。Cu(II) 的存在会降低 QD 的还原活性，并导致信号格式的颜色变化。建议的传感器可以使用便携式紫外线灯或直射阳光激活。在优化条件下，分光光度法的检测限 (S/N = 3) 为 10 nM，可见颜色变化的检测限为 0.1 μM。该传感系统用于量化实际样品中的 Cu(II)，例如河水和自来水。结果与使用电感耦合等离子体光谱法 (ICP) 获得的结果一致。该研究可能为基于量子点的传感器的发展提供新的思路。