Baofa Yu ^1* Yan Han ^2* Jian Zhang ^2* Dong Chen ^2*

• ¹ Beijing Cancer Hospital, Beijing, China
• ² Jinan Baofa Cancer Hospital, Jinan, Shandong Province, China

Objective: Nanotechnology offers many advantages in various fields of cancer therapy. Here, a new method of self-forming nanoparticles (Self-Nano) is described using ferric chloride (FeCl₃) and hydrogen peroxide (H2O2) to form the self-nanoparticles in an in vivo tumor. The treatment effect is evaluated.Method: A solution of 3% FeCl3 (0.5ml) and 1.8% H2O2 (1.0ml) was injected into the tumor. At various time points post-injection, tumors were collected, and sections were prepared for an electron microscope to evaluate the size of self-nano particles. Single-cell RNA sequencing (scRNA-seq) was used to analyze the immune changes and their effect their effects on tumor growth.Result: The formation of self-nano in vitro was observed and confirmed, with particles averaging 421 nm in size for the FeCl3 +H2O2 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.The FeCl3+H2O2 solution can form Fe₂O₃-based self-nanoparticles within tumors through H2O2-incubated oxidation of FeCI3. The self-nano remains effective for over 14 days, inducing ferroptosis and upregulating immune cells under magnetic field treatment. This approach offers a novel approach for cancer treatment that can be combined with other modalities.