It has been shown that DNA free radicals produced by ionizing radiation are usually fixed by O2 and then cause DNA damage which may lead to cell death if not repaired, so cells can survive while DNA damage is reduced under the low oxygen conditions.[22] With the purpose of evaluating whether the DDR ability of tumor cells was impaired after treatment with TPP‐LND@Lip, dynamic changes of intracellular DNA damage marker γ‐H2AX were detected by immunofluorescence assay. Here, H2AX is linked to neoplasm.