TAGRA 2025

Carbon quantum dots (CQDs) have garnered significant attention in recent years due to their strong fluorescent properties, high water solubility, and biocompatibility. These characteristics make them valuable in biomedical fields such as sensing, bioimaging, diagnosis, and treatment. Various materials, ranging from pure organic compounds to waste products, have been used as precursors in CQD synthesis. Cell culture studies generate significant amounts of waste, primarily from culture media, which is often discarded without further evaluation. Therefore, innovative approaches are needed to convert culture medium waste into high-value-added products. This study proposes a new procedure for producing CQDs using DMEM-based cell culture medium waste. The aim is to evaluate whether biological waste can be used as a functional precursor in CQD synthesis and to characterize the optical and biological properties of the obtained nanostructures. The synthesis was carried out using an environmentally friendly hydrothermal method under different conditions. The produced CQDs were examined for their absorption properties using UV-vis spectroscopy to determine their absorption characteristics, and their emission behavior was confirmed using fluorescence spectroscopy. Optical stability was monitored for 30 days in dark and light conditions, and no significant decrease in emission intensity was detected. Structural characterization was performed using TEM imaging. For biological evaluation, cytotoxicity studies were performed on different cell lines using the MTT assay. Cell viability was measured at varying concentrations, and the results indicated no significant toxicity at low and moderate doses. These findings point to the potential for safe use of waste-based CQDs in biomedical applications. Overall, the findings demonstrate that CQDs with strong optical stability and low cytotoxicity can be successfully synthesized from cell culture waste. This approach contributes to sustainable nanomaterial production by reducing material costs, minimizing waste, and decreasing environmental impact.