Herein, carbon dots (Cdots) with a single green emission peak and no response to metal ions were converted to a high sensitive and selective ratiometric fluorescent probe for the detection of Pb²⁺ through a simple chemical surface modification with glutathione. The as-prepared modified Cdots show two emission peaks at a 170 nm distance (from 522 to 692 nm) that were excited with a single excitation wavelength (390 nm) and responded oppositely to Pb²⁺. This probe provided an ideal ratiometric fluorescent probe for the determination of Pb²⁺ in a linear concentration range of 10–700 nM with a detection limit of 2.7 nM. Theoretical calculations based on density functional theory (DFT) theory demonstrated that the surface modification of Cdots with glutathione forms new emitting centers on the surface of Cdots that were suppressed through a photo-induced electron transfer (PET) process from the sulfur lone pair electrons of the surface glutathione ligands. However, in the presence of Pb²⁺, chemical binding between the sulfide groups of surface glutathione ligands of neighboring Cdots and Pb²⁺ aggregated Cdots. Upon this complex formation, the involved PET process was stopped and subsequently a new emission peak at longer wavelengths appeared.

在此，通过简单的谷胱甘肽化学表面修饰，将具有单个绿色发射峰且对金属离子无响应的碳点 (Cdots) 转化为高灵敏度和选择性的比例荧光探针，用于检测 Pb ^{2+ 。}所制备的改性碳点在 170 nm 距离（从 522 到 692 nm）处显示两个发射峰，这些发射峰被单个激发波长（390 nm）激发并与 Pb ²⁺响应相反。该探针为测定 Pb ^{2+提供了理想的比率荧光探针}在 10–700 nM 的线性浓度范围内，检测限为 2.7 nM。基于密度泛函理论 (DFT) 理论的理论计算表明，用谷胱甘肽对 Cdots 进行表面修饰会在 Cdots 表面形成新的发射中心，这些发射中心通过来自硫孤对电子的光致电子转移 (PET) 过程被抑制。表面谷胱甘肽配体。然而，在Pb 2+ 存在的情况下^，相邻碳点的表面谷胱甘肽配体的硫化物基团与Pb ²⁺聚集的碳点之间发生化学结合。在这种复杂的形成后，所涉及的 PET 过程停止，随后出现了更长波长的新发射峰。