Aliphatic substrates-mediated unique rapid room temperature synthesis of carbon quantum dots for fenofibrate versatile analysis.

Background: The current synthetic strategies for carbon dots (CDs) are usually time-consuming, rely on complicated processes, and need high temperatures and energy. Recent studies have successfully synthesized CDs at room temperature. Unfortunately, most CDs synthesized at room temperature are obtained under harsh reaction conditions, prepared using aromatic precursors, or need a long time to generate. Therefore, an energy-free room-temperature rapid synthesis of CDs under mild conditions using aliphatic substrates is important. We aim to provide an innovative approach to synthesizing CDs to be used to develop the first fluorescence-based assay of the non-fluorescent anti-hyperlipidemic drug, fenofibrate.

Results: We report an innovative, energy-free, and room-temperature preparation of fluorescent N-doped CDs utilizing aliphatic substrates in only 20 min. The synthesis was based on a self-exothermic Schiff base condensation reaction between methylglyoxal and ethylenediamine. The prepared CDs' antibacterial properties, biocompatibility, and cell-imaging ability were investigated. The fluorescence signal of the CDs was quantitively quenched upon adding increasing concentrations of fenofibrate in the range of 0.50-15.0 μg/mL. Therefore, the prepared CDs were applied as a nanosensor to develop the first fluorescence-based assay of fenofibrate. The reliability of the synthesized nanosensor was confirmed by the successful quantification of fenofibrate in pharmaceutical dosage forms, environmental water, weight loss herbal products, and dietary supplements. The obtained recovery ranged from 95.33 to 104.58 %. In addition, the minimal environmental impact of the developed fenofibrate sensing strategy was confirmed using the recently reported metrics.

Significance And Novelty: The key advantage of this work is the use of an energy-free approach to synthesize CDs rapidly under mild conditions without aromatic substrates. This opens a new window for the eco-friendly synthesis of CDs that avoids the drawbacks of the traditional methods. Additionally, it is the first fluorescence nanosensor for sensing fenofibrate in various matrices, avoiding the limitations of the previous methods, such as high cost, poor selectivity, and low sensitivity.