High‐Z Nanostructured Ceramics in Radiotherapy: First Evidence of Ta₂O₅‐Induced Dose Enhancement on Radioresistant Cancer Cells in an MV Photon Field

Abstract

This article pioneers a study into the use of the tantalum pentoxide nanoceramics as novel candidates for dose enhancement radiotherapy. It is revealed that a significant induced dose enhancement on radioresistant cancer cells expose to tantalum pentoxide nanoparticles and irradiated with 10 MV. In this study, in vitro experiments are performed. The radiobiological endpoint is clonogenic survival. We exposed 9L gliosarcoma cells to the nanoparticles at 50–500 μg mL−1 range and observed concentration‐dependent toxicity. Irradiation of the exposed and unexposed cells with 10 MV X‐ray photons reveals a sensitization enhancement ratio of 1.33. The associated cell survival curves demonstrate a significant change in shape, indicative of increased lethality of the local radiation environment. We postulate that this enhancement is primarily due to secondary electrons produced from photoelectric interaction and pair production, with backscattering on nanoparticle aggregates leading to increased radiobiological effectiveness.

Optimizing dose enhancement with Ta 2 O 5 nanoparticles for synchrotron microbeam activated radiation therapy

“…Ta 2 O 5 NPs are nano-structured ceramic particles that have shown to enhance conventional kV and MV radiotherapy [29,30]. Ta 2 O 5 NPs are manufactured according to Brown et al [28] and added to the cell culture flask to incubate for 24 hours. The toxicity to the cells with concentrations of 50-500 µg/mL, after 24 hrs incubation, was found to be very low, with cell clonogenic survival of 80-100% [28,30].…”

“…Ta 2 O 5 NPs are manufactured according to Brown et al [28] and added to the cell culture flask to incubate for 24 hours. The toxicity to the cells with concentrations of 50-500 µg/mL, after 24 hrs incubation, was found to be very low, with cell clonogenic survival of 80-100% [28,30]. Therefore, there is no lethality towards cells besides that induced due to ionising radiation.…”

“…Their use as a radiosensitizer was first reported by Brown et al [28] in conventional X-ray radiotherapy. These nanostructured ceramic particles have different aggregation properties than inert metal NPs.…”

“…High-Z nanoparticles (NPs) have been shown to improve the effectiveness of dose conformity to tumour tissue in the case of conventional unsegmented kilovoltage X-rays [19][20][21][22][23][24][25][26][27][28][29][30]. The advantages of NPs, besides the primary benefit of enhancing tumour radiosensitivity, often include biocompatibility, permeability to cell membranes due to their nano-scale dimensions, ability to specifically target certain tumours when coated and actively accumulate at tumour sites with leaky vasculature [21,22].…”

First proof of bismuth oxide nanoparticles as efficient radiosensitisers on highly radioresistant cancer cells

“…To solve these two issues, high Z nanoceramics, such as the promising tantalum pentoxide Ta 2 O 5 [12], have started to be investigated. The Ta 2 O 5 nanoparticle aggregates demonstrated the required radiosensitisation provided by the heavy Ta metal, and also the necessary biocompatibility thanks to the oxide form.…”