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BACKGROUND

Solar and galactic sources produce a combination of both low and high linear energy transfer (LET) particles. Human exposure to low LET leads to dramatically elevated levels of reactive oxygen species (ROS) resulting in oxidative stress, cell damage (such as DNA damage and cytotoxicity) and tissue degeneration [1, 2]. The design of radiation countermeasures for mitigation of oxidative stress damage is crucial for protection of astronaut health, especially for future long-term missions [3]. Antioxidants act as free radical scavengers and interceptors of reaction intermediates, thereby preventing radiation-induced DNA and cell damage [4, 5]. Many of these antioxidants have deleterious side effects or reduced potency after ingestion [6-8]. We are designing drug delivery systems to maximize the delivery of specific radio-protective agents to mitigate the effects of low LET radiation.