AUTHOR=Yu Baofa , Han Yan , Zhang Jian , Chen Dong 

TITLE=Formation of self-nanoparticles and the immune effect on tumors after injection of ferric chloride with H2O2 under magnetic field therapy

JOURNAL=Frontiers in Nanotechnology

VOLUME=6

YEAR=2024

URL=https://www.frontiersin.org/journals/nanotechnology/articles/10.3389/fnano.2024.1465888

DOI=10.3389/fnano.2024.1465888

ISSN=2673-3013

ABSTRACT=<sec><title>Objective</title><p>Nanotechnology offers many advantages in various fields of cancer therapy. This study describes a new method of self-forming nanoparticles (self-nano) using ferric chloride (FeCl₃) and hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) to form the self-nanoparticles in an <italic>in vivo</italic> tumor. The treatment effect is evaluated.</p></sec><sec><title>Method</title><p>A solution of 3% FeCl<sub>3</sub> (0.5 mL) and 1.8% H<sub>2</sub>O<sub>2</sub> (1.0 mL) was injected into the tumor. At various time points post-injection, tumors were collected, and sections were prepared for electron microscopy to evaluate the size of the self-nano particles. Single-cell RNA sequencing (scRNA-seq) was used to analyze the immune changes and their effect on tumor growth.</p></sec><sec><title>Result</title><p>The formation of self-nano <italic>in vitro</italic> was observed and confirmed, with particles averaging 421 nm in size for the FeCl<sub>3</sub> + H<sub>2</sub>O<sub>2</sub> solution. Over time points ranging from 1 to 14 days, the formed self-nano remained stable at a regular size of 421 ± 8 nm. The self-nano, primarily consisting of iron, induced ferroptosis under the influence of an external magnetic field, leading to tumor growth control through iron-induced cell death and immune reactions. These self-nanoparticles also showed stronger enrichment of pathways related to CD8<sup>+</sup> T effect cells (Teff), T cell activation, and regulation of T cell proliferation.</p></sec><sec><title>Conclusion</title><p>The FeCl<sub>3</sub> + H<sub>2</sub>O<sub>2</sub> solution can form Fe₂O₃-based self-nanoparticles within tumors through H<sub>2</sub>O<sub>2</sub>-incubated oxidation of FeCl<sub>3</sub>. The self-nano remains effective for over 14 days, inducing ferroptosis and upregulating immune cells under magnetic field treatment. This method offers a novel approach for cancer treatment that can be combined with other modalities.</p></sec>