Carbon quantum dots derived from fish scales as fluorescence sensors for detection of malachite green

In the current work, fish scale carbon quantum dots (FS-CQDs) were prepared from grass fish scales as precursors via a one-step hydrothermal approach to detect malachite green. The size distribution of FS-CQDs was uniform with an average particle diameter of 4.70 nm, which exhibited emission at 415 nm upon excitation at 310 nm. The FS-CQDs were demonstrated to selectively react with malachite green, leading to the fluorescence quenching effect. The established fluorescence nanosensor showed malachite green detection in the linear range of 0-150 mu M, with the limit of detection (LOD) of 4.4 mu M. The quenching type is static quenching, and the interaction was mainly driven by van der Waals interactions and the hydrogen bond, which were studied using the Stern-Volmer equation and thermodynamic analysis. Furthermore, the sensor was applied for the measurement of malachite green in real water samples and turbot with acceptable recovery of 91.6-115.5%. The utilization of fish scales in this study not only provided a new way of utilization of aquatic by-products, but also generated a novel alternative fluorescence nanosensor for the sensing field.