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

Objective 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 2 O 2 ) to form the self-nanoparticles in an in vivo tumor. The treatment effect is evaluated. Method A solution of 3% FeCl 3 (0.5 mL) and 1.8% H 2 O 2 (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. Result The formation of self-nano in vitro was observed and confirmed, with particles averaging 421 nm in size for the FeCl 3 + H 2 O 2 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 + T effect cells (Teff), T cell activation, and regulation of T cell proliferation. Conclusion The FeCl 3 + H 2 O 2 solution can form Fe₂O₃-based self-nanoparticles within tumors through H 2 O 2 -incubated oxidation of FeCl 3 . 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.