Normal breast epithelial MCF-10A cells to evaluate the safety of carbon dots

Abstract

The human normal breast cell line MCF-10A is being widely used as a model in toxicity studies due to its structural similarity to the normal human mammary epithelium. Over the years, application of carbon dots (C-dots) in biomedicine has been increasing due to their photoluminescence properties, biocompatibility, biosafety and possible applications in bioimaging and as drug carriers. In this work we prepared three different C-dots from the same set of carbon and nitrogen precursors (citric acid and urea, respectively) via three distinct bottom-up synthetic routes and their safety was tested against the normal breast cell line MCF-10A. The characterization results demonstrated a similar size range and composition for all the C-dots. The MCF-10A cells were treated with different concentrations of C-dots for 24, 48 and 72 h to evaluate the cell viability over time. For the 24 h incubation, there were no significant decreases in the viability of the MCF-10A cells. For the 48 h treatment, there was a significant decrease in the viability of the cells treated with calcination-based C-dots, but without significant cellular viability changes for microwave and hydrothermal-based C-dots. For 72 h, cells treated with hydrothermal-based C-dots have the most promising viability profile. Also, compared with paclitaxel, these C-dots have a safety profile very close to that of an antineoplastic in non-tumor cells. Our results suggest that these new C-dots have potential as imaging candidates or biosensing tools as well as drug carriers, and further investigation in animal models is needed for future application in medicine.

Fig. 1. 3D AFM images relative to the size of hydrothermal-, calcination- and microwave-based C-dots.

Fig. 2. Normalized excitation and emission spectra (in water) for hydrothermal-, calcination- and microwave-based C-dots.

Fig. 3. Relative C-dot cytotoxicity against MCF-10A cells after 24 h incubation through the MTT assay. The percentage of cell viability is represented as relative to the negative control. The values represent mean ± SEM (n = 3) (*p < 0.05).

Fig. 4. Relative C-dot cytotoxicity against MCF-10A cells after 48 h incubation through the MTT assay. The percentage of cell viability is represented as relative to the negative control. The values represent mean ± SEM (n = 2) (* p < 0.05) (** p <0.01).

Fig. 5. Relative C-dot cytotoxicity against MCF-10A cells after 72 h incubation through the MTT assay. The percentage of cell viability is represented as relative to the negative control. The values represent mean ± SEM (n = 2).

Fig. 6. Relative viabilities of MCF-10A cells after 24, 48 and 72 h treatments with paclitaxel vs. hydrothermal-based C-dots. The percentage of cell viability is represented as relative to the negative control. The values represent mean ± SEM. The data for paclitaxel are in agreement with the literature.