Fabrication and characterization of UV-emitting nanoparticles as novel radiation sensitizers targeting hypoxic tumor cells.

Radiation therapy is one of the primary therapeutic techniques for treating cancer, administered to nearly two-thirds of all cancer patients. Although largely effective in killing cancer cells, radiation therapy, like other forms of cancer treatment, has difficulty dealing with hypoxic regions within solid tumors. The incomplete killing of cancer cells can lead to recurrence and relapse. The research presented here is investigating the enhancement of the efficacy of radiation therapy by using scintillating nanoparticles that emit UV photons. UV photons, with wavelengths between 230 nm and 280 nm, are able to inactivate cells due to their direct interaction with DNA, causing a variety of forms of damage. UV-emitting nanoparticles will enhance the treatment in two ways: first by generating UV photons in the immediate vicinity of cancer cells, leading to direct and oxygen-independent DNA damage, and second by down-converting the applied higher energy X-rays into softer X-rays and particles that are more efficiently absorbed in the targeted tumor region. The end result will be nanoparticles with a higher efficacy in the treatment of hypoxic cells in the tumor, filling an important, unmet clinical need. Our preliminary experiments show an increase in cell death using scintillating LuPO4:Pr nanoparticles over that achieved by the primary radiation alone. This work describes the fabrication of the nanoparticles, their physical characterization, and the spectroscopic characterization of the UV emission. The work also presents in vitro results that demonstrate an enhanced efficacy of cell killing with x-rays and a low unspecific toxicity of the nanoparticles.

Commercialization of laser-induced breakdown spectroscopy for lead-in-paint inspection.

A study was undertaken to determine if laser-induced breakdown spectroscopy (LIBS) can be a practical and competitive alternative to x-ray fluorescence (XRF) methods for lead-in-paint inspection. Experiments in the laboratory confirmed that LIBS is suitable for detecting lead in paint at the hazard levels defined by federal agencies. Although we compared speed, function, and cost, fundamental differences between the XRF and LIBS measurements limited our ability to make a quantitative performance comparison. While the LIBS method can achieve the required sensitivity and offers a way to obtain unique information during inspection, the current component costs will likely restrict interest in the method to niche applications.

UV scintillating particles as radiosensitizer enhance cell killing after X-ray excitation.

BACKGROUND AND PURPOSE: Radiation therapy is the gold standard treatment for inoperable malignant tumors. However, due to the heterogeneity of the tumor, some regions are more radio resistant and can lead to metastasis and tumor recurrence. In this study, we propose combining traditional X-ray treatment with UVC-emitting LuPO4:Pr3+ nanoparticles (NPs) to increase the tumor control as well as to reduce tumor recurrence and metastasis. These NPs convert ionizing radiation into UVC-photons (UVC range: 200-280 nm) locally at the tumor site. Unlike X-ray, UVC-photons damage DNA directly via an oxygen-independent mechanism, which could improve treatment of radioresistant tumors such as hypoxic tumors. MATERIALS AND METHODS: The effect of X-ray generated UVC-photons was tested on human fibroblasts incubated with NPs prior to radiation treatment. The surviving fraction of the cells was assessed by means of colony formation assay. Experiments were performed on normal and UVC sensitive cell lines to demonstrate the presence of UVC photons during treatment. In addition, UV-specific DNA damages were investigated using an immunofluorescence assay to measure cyclopyrimidine dimers (CPDs). RESULTS: Combined treatment showed an increased cell death of over 50%, compared to radiation alone. This results in a dose equivalent of 4 Gy for the combined treatment with 2 Gy irradiation. The formation of CPDs and the increased effect on UV sensitive cells indicate the presence of UV photons. The generated amount of CPDs is comparable to an UVC exposure of about 15 J × m-2. CONCLUSION: Combining NPs with ionizing radiation results in a localized dose surge, which could increase tumor control. It could also allow lowering the total applied dose to minimize unwanted side effects to the surrounding normal tissue while maintaining tumor control.