Christopher E Hassan, Thomas J Webster

Given their low toxicity and natural presence in the human diet, selenium nanoparticles have been established as potential candidates for the treatment of numerous cancers. Red-allotrope selenium nanoparticles (rSeNPs) were synthesized and characterized in this study. Head and neck squamous cell carcinoma (HNSCC) and human dermal fibroblast (HDF) cells were cultured and exposed to rSeNPs at concentrations ranging from 0.01 to 100 μg rSeNP/mL media for 1-3 days. The toxicity of rSeNP toward HNSCC and HDFs was analyzed. Results indicated that the particles were approximately four times as cytotoxic toward HNSCC compared to HDFs, with their respective IC50 values at 19.22 and 59.61 μg rSeNP/mL media. Using statistical analysis, an effective dosage range for killing HNSCC cells while simultaneously minimizing damage to HDFs over a 3-day incubation period was established at 20-55 μg rSeNP/mL media. Observations showed that doses of rSeNP <5 μg rSeNP/mL media resulted in cell proliferation. Transmission electron microscopy images of HNSCC and HDF cells, both treated with rSeNPs, revealed that the rSeNPs became localized in the cytoplasm near the lysosomes and mitochondria. Analysis of cell morphology showed that the rSeNPs primarily induced HNSCC apoptosis. Collectively, these results indicated that rSeNPs are a promising option for treating HNSCC without adversely affecting healthy cells and without resorting to the use of harmful chemotherapeutics.