Oxygen/Nitric\nOxide Dual-Releasing Nanozyme for Augmenting\nTMZ-Mediated Apoptosis and Necrosis

Glioblastoma multiforme (GBM) is the most common and\naggressive\nmalignant brain tumor, with a poor prognosis. Temozolomide (TMZ) represents\nthe standard chemotherapy for GBM but has limited efficacy due to\npoor targeting and a hypoxic tumor microenvironment (TME). To address\nthese challenges, we developed a dual-gas-releasing, cancer-cell-membrane-camouflaged\nnanoparticle to deliver TMZ. This nanoceria, camouflaged with a cancer\ncell membrane (CCM-CeO<sub>2</sub>), targets explicitly GBM cells\nand accumulates in lysosomes, triggering the rapid release of TMZ.\nAdditionally, CCM-CeO<sub>2</sub> could release oxygen (O<sub>2</sub>) and nitric oxide (NO) in response to the TME. Synthesized using d-arginine, catalytic nanoceria could decompose excessive hydrogen\nperoxide (H<sub>2</sub>O<sub>2</sub>) in the TME to produce O<sub>2</sub>, while d-arginine could nonenzymatically react with\nH<sub>2</sub>O<sub>2</sub> to generate NO. CCM-CeO<sub>2</sub> could\npenetrate GBM spheroids to a depth of 148.3 ± 31 μm, with\nthe O<sub>2</sub> and NO produced, reducing HIF-1α protein expression.\nWhen loaded with TMZ, CCM-CeO<sub>2</sub> could increase the intracellular\nROS produced by TMZ, leading to lysosome membrane permeabilization\nand notably augmented apoptosis and necrosis in GBM cells. An in vitro\nantitumor assay using spheroids showed that CCM-CeO<sub>2</sub> reduced\nthe IC<sub>50</sub> value of TMZ from 174.5 to 42.6 μg/mL, likely\ndue to the catalase-like activity of nanoceria. These results suggest\nthat alleviating hypoxia and increasing ROS produced by chemotherapeutics\ncould be an effective therapeutic strategy for treating GBM.