Radiotherapy Enhancement by Ti3C2Tx MXenes

Radiotherapy is an integral part of cancer therapy. Due to the low tissue specificity of radiation, damage to tumor-surrounding healthy tissue remains a major concern. Radio-enhancers based on inorganic nanomaterials have attracted considerable attention in recent years. In addition to widely exploited metal and metal oxides nanoparticles, 2D materials may offer potential advantages due to their intrinsically high specific surface area. Here, we report on the promising radio-enhancement properties of Ti3C2Tx MXenes. We show that Ti3C2Tx MXenes are readily internalized and well-tolerated by mammalian cells. In contrast to MXenes suspended in aqueous buffers which fully oxidize within days (yielding rice-grain shaped rutile nanoparticles), MXenes internalized by cells display slower oxidation rates, in line with cell-free experiments showing slower oxidation in cell media and lysosomal buffers compared to antioxidant-devoid dispersants. The MXenes show potent radio-enhancement properties with dose enhancement factors of up to 2.5 in human soft tissue sarcoma cells and no toxicity towards healthy human fibroblasts. Benchmarking against oxidized MXenes and commercial titanium dioxide nanoparticles indicates superior radio-enhancement properties of the intact 2D titanium carbide flakes. Taken together, this work provides direct evidence for the potent radio-enhancement properties of Ti3C2Tx MXenes rendering them a promising candidate material for radiotherapy enhancement.