Facile synthesis of carbon quantum dot/silver nanocomposite and its application for colorimetric detection of methimazole

Here we present a very simple and fast method for preparation of carbon quantum dot/silver (CQD/Ag) nanocomposites at room temperature. Glucose-derived CQDs were prepared by a facile microwave-assisted method and used as both reducing and stabilizing agents for synthesis of CQD/Ag nanocomposites. We found that a unique interaction between as-prepared nanocomposites and anti-thyroid drug methimazole occurs in the solution, which results in a sharp color change from yellow to red. At the same time, the intensity of surface plasmon resonance peak of CQD/Ag nanocomposites at 400nm decreases and a new peak appears at higher wavelengths. This finding formed a basis for developing a new colorimetric detection method for methimazole. The calibration curve for this drug was linear in the concentration range of 2.0–40μgL−1 with a detection limit of 1.0μgL−1. The method was applied to the determination of methimazole in urine samples with satisfactory results.