Smartphone-Integrated Ratiometric Fluorescent Sensing Platform Based on Carbon Dots for One-Step Detection of...

An ability to effectively detect glyphosate residues in food and the environment on-site remains a challenge. Herein, we developed a ratiometric fluorescent sensing platform based on blue fluorescent carbon dots (B-CDs) and red carbon dots (R-CDs) for rapid, visual, and quantitative detection of glyphosate. Although B-CDs, which were functionalized with abundant amino and hydroxyl groups, caused glyphosate-mediated aggregation-caused quenching (ACQ) via hydrogen bonding effect, R-CDs acted as a stable internal reference. The system could detect glyphosate in one step within 20 s and had a low detection limit of 2.87 μM. During the detection process, the fluorescent color changes from blue to red. On-site detection can be achieved by using the RGB analysis integrated in the smartphone. The sensor had high selectivity to glyphosate, despite the presence of metal ions, biomolecules, and various pesticides. It was successfully applied to detect actual water samples with recovery rates of 81.8%-96.6% (RSD ≤ 11.1%). With its rapid response, smartphone compatibility, and robustness in detecting complex matrices, the proposed sensor has promising potential for the monitoring of glyphosate in agricultural and environmental samples.