In this work, the in situ reduction of Ag⁺ by carbon quantum dots (CQDs) to the formation of CQDs-silver nanocomposite (CQDs-silver NPs) was exploited to develop a facile and ultrasensitive colorimetric sensor platform. Due to the high affinity between Ag and melamine, melamine could significantly induce the well-dispersed CQDs-silver NPs aggregation. Consequently, the solution color of CQDs-silver NPs changed from bright yellow to red. Based on this finding, we proposed a new colorimetric method to qualitatively and quantitatively detect melamine by the naked eyes and UV–vis spectroscopy, respectively. Under the optimum conditions, the linearity of melamine with the solution absorbance (ΔR) was plotted in the concentration range of 1 × 10⁻¹⁰–1 × 10⁻⁸ g/mL (y = 0.55 + 0.049x, R = 0.9596) and 2.5 × 10⁻⁸–5 × 10⁻⁷ g/mL (y = 3.43 + 0.42x, R = 0.9961). The developed method showed excellent detection sensitivity for melamine with the detection limit as low as 7.9 × 10⁻¹² g/mL (eq. 65.3 pmol L⁻¹). Finally, the developed method was employed to detect the amount of melamine in cow milk and milk powderand a recovery of 87.6–116%, and RSD of 1.6–3.9% was achieved.

在这项工作中，利用碳量子点（CQDs）原位还原Ag ⁺以形成CQDs-银纳米复合材料（CQDs-银NPs），以开发一种简便且超灵敏的比色传感器平台。由于银与三聚氰胺之间的亲和力高，三聚氰胺可以显着诱导分散良好的CQDs-银NPs聚集。因此，CQDs-银色NP的溶液颜色从亮黄色变为红色。基于这一发现，我们提出了一种新的比色法，分别通过肉眼和紫外-可见光谱法定性和定量检测三聚氰胺。在最佳条件下，将三聚氰胺与溶液吸光度（ΔR）的线性关系绘制在1×10 ^-10 –1×10 ^-8的浓度范围内 g / mL（y = 0.55 + 0.049x，R  = 0.9596）和2.5×10 ^-8 –5×10 ^-7  g / mL（y = 3.43 + 0.42x，R  = 0.9961）。所开发的方法对三聚氰胺显示出极好的检测灵敏度，检测限低至7.9×10 ^-12  g / mL（当量65.3 pmol L ^-1）。最终，该发达的方法用于检测牛奶和奶粉中三聚氰胺的含量，回收率为87.6–116％，RSD为1.6–3.9％。