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Measurement of Hydroxyl Radicals in Radiolized Water Systems

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Z Ouyang

Z Ouyang1,2*, G Strack1 , E Sajo1 , W Ngwa1,2 , (1) University of Massachusetts Lowell, Lowell, MA, (2) Brigham and Women's Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA


SU-F-T-676 (Sunday, July 31, 2016) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: Hydroxyl radicals can be produced within tissue by radiation therapy, and they are largely responsible for DNA damage and cell killing. Coumarin-3-carboxylic acid (3-CCA) and crystal violet are reported to react with hydroxyl radicals and can be used for fluorescence and absorbance measurements, respectively. This study assesses the ability of hydroxyl measurement for both 3-CCA and crystal violet in radiolized water systems in order to provide dosimetric information in radiation chemistry and radiation biology experiments.

Methods: 3-CCA and crystal violet were both dissolved in phosphate buffered saline (PBS, pH 7.4) with final concentrations 0.5 mg/mL and 0.05 mg/mL. 3-CCA and control solutions (PBS only) were loaded in black bottom 96-well plates. Crystal violet and control solutions were loaded in clear bottom 96-well plates. The prepared solutions were irradiated at 2 Gy using a small animal radiation research platform. Fluorescence reading with 360 nm excitation wavelength and 485 nm emission wavelength was done for 3-CCA, and absorbance reading at wavelength 580 nm was done for crystal violet before and after radiation.

Results: 3-CCA showed clear difference in fluorescence before and after radiation, which suggested hydroxyl production during radiation. However, crystal violet absorbance at 580 nm was not changed significantly by radiation.

Conclusion: The overall conclusion is that 3-CCA can be used for hydroxyl measurement in radiolized water systems, while crystal violet cannot, although crystal violet is reported widely to react with hydroxyl radicals produced in Fenton reactions. Possible reasons could relate to reaction pH.

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