Multicomponent nanosystem activated by low-dose irradiation in human cancer cells in 2D monolayers and 3D spheroids models

Cancer remains one of the leading causes of mortality worldwide, and conventional treatments such as photodynamic therapy (PDT) and radiotherapy often suffer from limited efficacy and significant side effects. To address these challenges, we developed a biocompatible hybrid nanosystem composed of two dimensional tungsten disulfide (WS₂) nanoflakes grafted with Au nanoparticles and functionalized with a porphyrin derivative. This platform was designed as a radiosensitizer capable of being activated by low energy, low dose X ray irradiation to selectively enhance cancer cell killing. The nanosystem was evaluated in vitro using HT 29 human colorectal cancer cells in both 2D monolayers and 3D spheroid models. In conventional 2D culture, we assessed cellular internalization and therapeutic response following low dose irradiation (2 Gy, 40 keV) through analyses of gene expression (SOD1, HMOX1, BAX, and BCL2), cell cycle modulation, apoptosis induction, and clonogenic survival. In 3D spheroids, treatment efficacy was monitored by quantifying spheroid area reduction over time, as well as apoptosis and cell proliferation (Ki-67 staining), while nanosystem internalization was determined using two-photon excitation (TPE) microscopy. Furthermore, preliminary results using 2D cultures of the triple negative human breast cancer cell line MDA MB 231 confirmed the broader applicability of the approach. Overall, our findings demonstrate the promising potential of this novel hybrid nanosystem as an effective radiosensitizer for low dose radiotherapy. This work was supported by the EIC PathFinder project PERSEUS (grant agreement no. 101099423).