A facile one-step hydrothermal method was developed to synthesize nitrogen-doped carbon quantum dots (N-CQDs) by utilizing hexamethylenetetramine as the carbon and nitrogen source. The quantum yield (QY) of 21.7% was under the excitation wavelength of 420 nm with maximum emission at 508 nm. This N-CQD fluorescent probe has been successfully applied to selectively determine the concentration of copper ion (Cu²⁺) with a linear range of 0.1–40 μM and a limit of detection of 0.09 μM. In addition, the fluorescence of N-CQDs could be effectively quenched by Cu²⁺ and specifically recovered by glutathione (GSH), which render the N-CQDs as a premium fluorescent probe for GSH detection. This fluorescence “turn-on” protocol was applied to determine GSH with a linear range of 0.1–30 μM as well as a detection limit of 0.05 μM. For pH detection, there is good linearity in the pH range of 2.87–7.24. Furthermore, N-CQD is a promising and convenient fluorescent pH, Cu²⁺, and glutathione sensor with brilliant biocompatibility and low cytotoxicity in environmental monitoring and bioimaging applications.

开发了一种简便的一步水热法，以六亚甲基四胺为碳氮源，合成了氮掺杂的碳量子点（N-CQDs）。在420 nm的激发波长下，量子产率（QY）为21.7％，最大发射在508 nm。该N-CQD荧光探针已成功应用于选择性测定铜离子（Cu ²⁺）的浓度，其线性范围为0.1–40μM，检出限为0.09μM。此外，Cu ²⁺可以有效地猝灭N-CQDs的荧光。并被谷胱甘肽（GSH）专门回收，使N-CQDs成为用于GSH检测的优质荧光探针。该荧光“开启”方案用于测定GSH，线性范围为0.1–30μM，检出限为0.05μM。对于pH检测，在2.87–7.24的pH范围内具有良好的线性。此外，N-CQD是一种有前途且方便的荧光pH值，Cu ²⁺和谷胱甘肽传感器，在环境监测和生物成像应用中具有出色的生物相容性和低细胞毒性。