Emergent Nontoxic N-CQDs as Functional Nanopest Repellents against Neonicotinoid Pesticides for Sustainable Agriculture

The extensive use of neonicotinoid pesticides has greatly enhanced crop yields. However, their water solubility, environmental persistence, and toxicity to nontarget species raise ecological and health concerns. In this research, we present nitrogen-doped carbon quantum dots (N-CQDs) approximately 6 nm in size that serve as a multifunctional platform. They can detect neonicotinoid pesticides through a simple fluorescence turn-off method, diminish their effectiveness in water and agricultural settings, and act as nanopesticide repellents. The N-CQDs exhibit strong, stable fluorescence, numerous surface functional groups, and high biocompatibility, enabling selective interactions with compounds such as imidacloprid, thiamethoxam, clothianidin, thiacloprid, and nicotine. Characterization techniques such as TEM, PXRD, FT-IR, XPS, EDX, UV–vis, 1 H NMR, and fluorescence spectroscopy were used to analyze the nanosensor’s morphology and features. The sensor achieved a detection limit of 23 nM, indicating excellent sensitivity. Spectroscopic analyses indicate that N-CQDs form strong noncovalent associations and stable complexes with neonicotinoid pesticides, accompanied by a noticeable decrease in their biological activity as observed in functional experiments. Practical tests, including cytotoxicity assays, fruit bioassays, and ant-repellence trials, confirm that N-CQDs can effectively neutralize neonicotinoid pesticides in real-world conditions without being toxic or unsafe. This approach offers a sustainable way to address neonicotinoid pesticide pollution, promoting safer farming methods and environmental preservation. Surprisingly, the nanosensor not only detects and mitigates neonicotinoid pesticides but also serves as a nanopest repellent in real-world agricultural use.