A novel sulfate-loaded iron-nitrogen co-doped carbon quantum dots (SO₄^2–-CQDs)-based fluorescent method was synthesized by the facile and environmentally friendly pyrolysis of persimmon frost (carbon source) and (NH₄)₂Fe(SO₄)₂·6H₂O. After SMMC-7721 cells were incubated with the SO₄^2–-CQDs for 24 h, more than 95% of the cells remained viable, even at a high concentration of the SO₄^2–-CQDs, indicating excellent biocompatibility and low toxicity. In addition, it was able to be taken up by the cells to emit their bright blue fluorescence after excitation at 365 nm, indicating suitable cell permeability. The SO₄^2–-CQDs also exhibited a unique response to changes in pH, which was applied in the detection of OPs by relying on the production of acetic acid from the hydrolysis of acetylcholine (ACh) by acetylcholinesterase (AChE), which decreased the pH and engendered an increase in the fluorescence of the SO₄^2–-CQDs; however, the inhibition of AChE by glyphosate resulted in little influence on fluorescence intensity due to the lack of acetic acid produced. This mechanism was the basis for the development of a sensitive assay for the detection of glyphosate. The resulting assay had a limit of detection of 0.066 ng/mL. Furthermore, the method was successfully applied for the precise and accurate monitoring of the concentration, distribution, and variation of glyphosate residues in chives and cultivated soil. Therefore, the proposed method was anticipated to provide a promising alternative for other detection methods to enable the reliable analysis of OPs in food products.

以柿霜（碳源）和( _{NH 4} ) ² Fe ₍ SO ₄ ) ₂ ·6H ₂ O. SMMC-7721 细胞与 SO ₄ ^2– -CQD 一起孵育 24 小时后，超过 95% 的细胞仍然存活，即使在高浓度的 SO ₄ ^{2–下也是如此}-CQDs，表明优良的生物相容性和低毒性。此外，在365 nm激发后，它能够被细胞吸收，发出明亮的蓝色荧光，表明细胞具有合适的渗透性。SO ₄ ^2– -CQDs 对 pH 值的变化也表现出独特的响应，通过乙酰胆碱酯酶 (AChE) 水解乙酰胆碱 (ACh) 产生的乙酸用于检测 OPs，从而降低pH 值并导致 SO ₄ ^2-的荧光增加-CQD；然而，由于没有产生乙酸，草甘膦对 AChE 的抑制对荧光强度的影响很小。这种机制是开发用于检测草甘膦的灵敏测定法的基础。所得测定的检测限为 0.066 ng/mL。此外，该方法成功地应用于精确监测韭菜和耕地土壤中草甘膦残留的浓度、分布和变化。因此，所提出的方法有望为其他检测方法提供一种有前途的替代方法，以实现对食品中 OP 的可靠分析。