Ultrafast microwave-assisted green synthesis of nitrogen-doped carbon dots as turn-off fluorescent nanosensors for determination of the anticancer nintedanib: Monitoring of environmental water samples

• This study presents the first spectrofluorimetric method for nintedanib analysis. • Ultrafast green synthesis of N-CQDs was performed in less than one minute. • Analysis of nintedanib relies on the quantitative quenching of N-CQDs' fluorescence. • The detection limit reaches 0.14 μg/mL in environmental water samples. • The method's greenness and practicality were demonstrated using different metrics. This study unveils a swift and sustainable approach for the synthesis of nitrogen-doped carbon quantum dots (N-CQDs) from radish leaves and urea, conducted by microwave assistance within only 50 seconds, showcasing remarkable efficiency. Comprehensive characterization confirmed the distinctive optical properties of the N-CQDs, with a quantum yield of 19.76 %, highlighting their potential as fluorescent nanosensors. The N-CQDs exhibit turn-off fluorescence properties for sensing the anticancer drug nintedanib in different environmental water samples, including hospital discharge water, sewage water, tap water, and river water. The method exhibits excellent linearity within a concentration range of 1.0–20.0 µg/mL, with a correlation coefficient exceeding 0.999 and a low detection limit down to 0.14 μg/mL. The assay of nintedanib in various environmental water samples demonstrated the applicability and sensitivity of the N-CQDs as a detection platform. The ComplexMoGAPI, AGREE, and Green Certificate-modified Eco-Scale metrics demonstrated the method's exceptional eco-friendliness and sustainability. Additionally, the BAGI tool was employed to assess the method's economic viability, applicability, and practicality. All the tools demonstrated the sustainability and feasibility of the developed approach, as well as its appropriateness for the routine analysis of the examined drug. This work is considered the first spectrofluorimetric approach for the analysis of nintedanib. This innovative study also paves the way for eco-friendly nanosensors with diverse applications in environmental monitoring.