The purpose of this study was to construct and characterize iron oxide nanoparticles (IONP co) for intracellular delivery of the anthracycline doxorubicin (DOX; IONP DOX) in order to induce tumor cell inactivation. More than 80% of the loaded drug was released from IONP DOX within 24 h (100% at 70 h). Efficient internalization of IONP DOX and IONP co in HeLa cells occurred through pino-and endocytosis, with both IONP accumulating in a perinuclear pattern. IONP co were biocompatible with maximum 27.9% ± 6.1% reduction in proliferation 96 h after treatment with up to 200 µg/mL ionp co. Treatment with IONP DOX resulted in a concentration-and time-dependent decrease in cell proliferation (IC 50 = 27.5 ± 12.0 μg/mL after 96 h) and a reduced clonogenic survival (surviving fraction, SF = 0.56 ± 0.14; versus IONP co (SF = 1.07 ± 0.38)). Both IONP constructs were efficiently internalized and retained in the cells, and IONP DOX efficiently delivered DOX resulting in increased cell death vs ionp co. Chemotherapy is an essential systemic component in modern multimodal cancer treatment, yet one of the main disadvantages of anticancer chemotherapeutics is toxicity to the normal tissue. The use of nano-sized carriers as intracellular transporters for the active substances not only promises to reduce the total drug amount administered, while potentially improving the treatment's efficiency by enhancing the local dose in the tumour, but also can help to improve the specificity and targeting of the active substance, thereby reducing the side-effects associated with chemotherapy 1. In nano-carriers, drugs can be transported to the tumour site through the enhanced permeability and retention effect 2-4 , magnetic targeting 5-8 and protected until they find a triggering stimuli to release, like pH variations 9-12 , temperature 13,14 , radiation-induced release 15-19. The use of iron oxide nanoparticles in the construction of nano-systems for the delivery of chemotherapeutics not only enables active magnetic targeting to the tumour site, but also offers additional functions that make them suitable for diagnosis (contrast substance in MRI 20-22) or enhanced anticancer activity using hyperthermia 23. Conjugation with other compounds can add to the multi-functionality of these nanomaterials and implement properties such as increased and/or specific 24-26 internalization in cancer cells, but can also help to modulate the

While the dose-response relationship of radiation-induced bystander effect (RIBE) is controversial at low and high linear energy transfer (LET), mechanisms and effectors of cell-to-cell communication stay unclear and highly dependent of cell type. In the present study, we investigated the capacity of chondrocytes in responding to bystander factors released by chondrosarcoma cells irradiated at different doses (0.05 to 8 Gy) with X-rays and C-ions. Following a medium transfer protocol, cell survival, proliferation and DNA damages were quantified in bystander chondrocytes. The bystander factors secreted by chondrosarcoma cells were characterized. A significant and major RIBE response was observed in chondrocyte cells (T/C-28a2) receiving conditioned medium from chondrosarcoma cells (SW1353) irradiated with 0.1 Gy of X-rays and 0.05 Gy of C-ions, resulting in cell survivals of 36% and 62%, respectively. Micronuclei induction in bystander cells was observed from the same low doses. The cell survival results obtained by clonogenic assays were confirmed using impedancemetry. The bystander activity was vanished after a heat treatment or a dilution of the conditioned media. The cytokines which are well known as bystander factors, TNF-α and IL-6, were increased as a function of doses and LET according to an ELISA multiplex analysis. Together, the results demonstrate that irradiated chondrosarcoma cells can communicate stress factors to non-irradiated chondrocytes, inducing a wide and specific bystander response related to both doses and LET. Electronic supplementary material The online version of this article (10.1007/s12079-019-00515-9) contains supplementary material, which is available to authorized users.