Sustainable deep eutectic solvent-engineered clove-derived carbon dots as a single sensing platform for the detection of multiple antioxidants

Abstract

Antioxidants are essential for mitigating oxidative stress and preserving cellular homeostasis, underscoring the need for sustainable, analytically robust detection platforms. Here, we propose an environmentally friendly and effective method for producing fluorescent carbon dots (CDs) from clove (Syzygium aromaticum) under hydrothermal conditions utilizing a deep eutectic solvent (choline chloride and urea). This ecologically friendly method eliminates the need for harmful reagents and produces very uniform CDs with an average particle size of ∼2.1 nm and a fluorescence quantum yield of 22.5%. Detailed structural and compositional investigations employing HR-TEM, FT-IR, and XPS reveal effective carbonization as well as the presence of several surface functional groups that contribute to the excellent optical characteristics. The as-prepared CDs show excitation-dependent fluorescence emission, outstanding photostability, and remarkable stability throughout a wide pH, ionic strength, and irradiation time range. With low detection limits of 0.25 µM and 0.14 µM, respectively, the CDs are extremely sensitive and selective fluorescent nanoprobes for quercetin (QT) and riboflavin (RF). The improved sensing performance is ascribed to the effective interactions between the analytes and the surface functionalities of the CDs. Overall, this study demonstrates how deep eutectic solvent engineering and biomass-derived precursors may work together to create functional nanomaterials in a sustainable manner. The proposed CDs have considerable potential for use in antioxidant sensing as well as in extensive bioanalytical and environmental monitoring systems.