EVALUATION OF GLUCOSE UPTAKE BY BREAST CANCER CELLS USING QUANTUM DOT NANOPROBES

Cancer cells may exhibit elevated glucose uptake due to their reliance on aerobic glycolysis for energy production, a phenomenon known as the Warburg effect. Understanding how this altered metabolism varies among cancer cell types is essential for advancing diagnostic tools and therapeutic strategies. In this context, quantum dots (QDs), semiconductor nanocrystals with intense fluorescence, high photostability, and an active surface for conjugation, represent promising nanoprobes to better understand the Warburg effect. In the present study, a fluorescent conjugate based on 1-thiol-β-D-glucose (Glc) and QDs was prepared and applied to investigate the uptake profile of this carbohydrate by breast cancer cells of different malignancy grades (MDA-MB-231 and MCF-7). The uptake was evaluated by fluorescence microscopy and flow cytometry. Glc was conjugated with QDs through the affinity of its thiol group for the QD semiconductor surface, and the conjugation was analyzed and confirmed by Fourier-transform infrared spectroscopy, Zeta potential measurements, and fluorescence correlation spectroscopy. The fluorescence microscopy assay revealed the presence of the nanoprobes in the cytoplasm of the cells, after only 15 min. According to flow cytometry, after 15 min of incubation of the QDs-Glc conjugates with the cells, a labeling of about 67.3% was observed in MDA-MB-231 cells and 28.1% in MCF-7. Extending incubation to 30 min increased labeling to 96.6% and 72%, for the MDA-MB-231 and MCF-7 cell lines, respectively. These results indicate that MDA-MB-231 cells exhibited higher uptake compared to MCF-7, consistent with their level of aggressiveness, consistent with their heightened glycolytic activity. Therefore, the study demonstrated the potential of the QDs-Glc nanoprobe to detect differential glucose uptake profiles among cancer cell lines, which is relevant for improving the understanding of the Warburg effect and supporting advances in cancer diagnosis and treatment. 

This work was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco (FACEPE), INCT de Fotônica, and INCT de Fotônica Aplicada a Biologia Celular.