Understanding the Role of Surface Charge in Cellular Uptake and X‑ray-Induced ROS Enhancing of Au−Fe3O4 Nanoheterodimers

Klein S, Stiegler L, Harreiß C, Distel L, Neuhuber W, Spiecker E, Hirsch A, Kryschi C (2018)

Publication Language: English

Publication Type: Journal article, Original article

Publication year: 2018


Pages Range: 2002-2011

DOI: 10.1021/acsabm.8b00511


Au−Fe3O4 nanoheterodimers were obtained by thermally decomposing iron oleate on presynthesized gold nanoparticles. Water solubility as well as surface charges were achieved by encapsulating the initially hydrophobic Au−Fe3O4 nanoheterodimers in a self-assembled bilayer shell formed either by 1-octadecylpyridinium, providing positive surface charges, or by 4-dodecylbenzenesulfonate, yielding a negatively charged surface. The surface charge and surface architecture were shown to control both the cellular entry and the intracellular trafficking of the Au−Fe3O4 nanoheterodimers. The positively charged (1-octylpyridinium-terminated) Au−Fe3O4 nanoheterodimers were internalized by both breast cancer cells (MCF-7) and epithelial cells (MCF-10 A), wherein they were electrostatically bound at the negatively charged membranes of the cell organelles and, in particular, adsorbed onto the mitochondrial membrane. The treatment of MCF-7 and MCF-10 cells with a fractional X-radiation dose of 1 Gy resulted into a large increase of superoxide production, which arose from the Au−Fe3O4 nanoheterodimer-induced mitochondrial depolarization. In contrast, the negatively charged (4-dodecylbenzenesulfonateterminated) Au−Fe3O4 nanoheterodimers preferentially invaded the cancerous MCF-7 cells by direct permeation. X-ray treatment of MCF-7 cells, loaded with anionic Au−Fe3O4 nanoheterodimers, yielded the increase of both hydroxyl radical and cytoplasmic superoxide formation. The X-radiation-induced activation of the Fe3O4 surfaces, consisting of Fe2+ and Fe3+ cations, triggered the catalysis of the hydroxyl radical production, whereas superoxide formation presumably occurred through X-rayinduced photoelectron emission near the Au surface. Since hydroxyl radicals are highly cytotoxic and the negatively charged Au−Fe3O4 NHDs spare the healthy MCF-10A cells, these Au−Fe3O4 nanoheterodimers exhibit a higher potential for radiation therapy than the positively charged Au−Fe3O4 nanoheterodimers. Encouraging results from the clonogenic cell survival assay and DMF calculations corroborate the excellent performance of the anionic Au−Fe3O4 nanoheterodimers as an X-ray dosage enhancer.

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Klein, S., Stiegler, L., Harreiß, C., Distel, L., Neuhuber, W., Spiecker, E.,... Kryschi, C. (2018). Understanding the Role of Surface Charge in Cellular Uptake and X‑ray-Induced ROS Enhancing of Au−Fe3O4 Nanoheterodimers. ACS Applied Bio Materials, 2002-2011. https://doi.org/10.1021/acsabm.8b00511


Klein, Stefanie, et al. "Understanding the Role of Surface Charge in Cellular Uptake and X‑ray-Induced ROS Enhancing of Au−Fe3O4 Nanoheterodimers." ACS Applied Bio Materials (2018): 2002-2011.

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