Applications of radiation processing in combination with conventional treatments to assure food safety: New development

Spice extracts under the form of essential oils (Eos) were tested for their efficiency to increase the relative bacterial radiosensitivity (RBR) of Listeria monocytogenes, Escherichia coli and Salmonella typhi in culture media under different atmospheric conditions. The selected Eos were tested for their ability to reduce the dose necessary to eliminate E. coli and S. typhi in medium fat ground beef (23% fat) and Listeria in ready-to-eat carrots when packed under air or under atmosphere rich in oxygen (MAP). Results have demonstrated that depending of the compound added and the combined treatment used, the RBR increased from 2 to 4 times. In order to evaluate the industrial feasibility, EOs were added in ground beef at a concentration which does not affect the taste and treated at a dose of 1.5 kGy. The content of total mesophilic aerobic, E. coli, Salmonella, total coliform, lactic acid bacteria, and Pseudomonas was determined during 28 days. The results showed that the combined treatment (radiation and EOs) can eliminate Salmonella and E. coli when done under air. When done under MAP, Pseudomonas could be eliminated and a shelf life of more than 28 days was observed. An active edible coating containing EOs was also developed and sprayed on ready-to-eat carrots before radiation treatment and Listeria was evaluated. A complete inhibition of Listeria was obtained at a dose of 0.5 kGy when applied under MAP. Our results have shown that the combination of an edible coating, MAP, and radiation can be used to maintain the safety of meat and vegetables.     

Enhancement of radiosensitivity of oral carcinoma cells by iodinated chlorin p6 copper complex in combination with synchrotron X‐ray radiation

The combination of synchrotron X‐ray radiation and metal‐based radiosensitizer is a novel form of photon activation therapy which offers the advantage of treating malignant tumors with greater efficacy and higher precision than conventional radiation therapy. In this study the anticancer cytotoxic efficacy of a new chlorophyll derivative, iodinated chlorin p₆ copper complex (ICp₆‐Cu), combined with synchrotron X‐ray radiation (8–10 keV) in two human oral cancer cell lines is explored. Pre‐treatment of cells with 20 µM and 30 µM ICp₆‐Cu for 3 h was found to enhance the X‐ray‐induced cytotoxicity with sensitization enhancement ratios of 1.8 and 2.8, respectively. ICp₆‐Cu localized in cytoplasm, mainly in lysosomes and endoplasmic reticulum, and did not cause any cytotoxicity alone. The radiosensitization effect of ICp₆‐Cu accompanied a significant increase in the level of reactive oxygen species, damage to lysosomes, inhibition of repair of radiation‐induced DNA double‐strand breaks, increase in cell death and no significant effect on cell cycle progression. These results demonstrate that ICp₆‐Cu is a potential agent for synchrotron photon activation therapy of cancer.     

Radiobiological Implications of Nanoparticles Following Radiation Treatment

Materials with a high atomic number (Z) are shown to cause an increase in the level of cell kill by ionizing radiation when introduced into tumor cells. This study uses in vitro experiments to investigate the differences in radiosensitization between two cell lines (MCF-7 and U87) and three commercially available nanoparticles (gold, gadolinium, and iron oxide) irradiated by 6 MV X-rays. To assess cell survival, clonogenic assays are carried out for all variables considered, with a concentration of 0.5 mg mL⁻¹ for each nanoparticle material used. This study demonstrates differences in cell survival between nanoparticles and cell line. U87 shows the greatest enhancement with gadolinium nanoparticles (2.02 ± 0.36), whereas MCF-7 cells have higher enhancement with gold nanoparticles (1.74 ± 0.08). Mass spectrometry, however, shows highest elemental uptake with iron oxide and U87 cells with 4.95 ± 0.82 pg of iron oxide per cell. A complex relationship between cellular elemental uptake is demonstrated, highlighting an inverse correlation with the enhancement, but a positive relation with DNA damage when comparing the same nanoparticle between the two cell lines.     

Topotecan‐Loaded Mesoporous Silica Nanoparticles for Reversing Multi‐Drug Resistance by Synergetic Chemoradiotherapy

Multi‐drug resistance (MDR) has become a major challenge for the further improvement of chemotherapy. Thus, more effective strategies for further enhancing the treatment against cancer by overcoming MDR are warranted. In this study, by the encapsulation of the radiosensitizing drug TPT into mesoporous silica nanoparticles (MSNs), the combined use of drug‐delivered chemotherapy and high‐energy X‐ray induced radiotherapy could produce synergetic chemoradiotherapeutic effects to kill multi‐drug resistant cells through significant DNA damage, thus leading to an efficient circumvention of MDR. We hope that this synergetic dual‐mode treatment strategy may achieve higher oncolytic efficacy and find use in future clinical anti‐MDR applications.