Nanoparticles can suffocate tumors. In a recent paper published in Nature Nanotechnology, Prof. Bu Wenbo of ECNU and his coworkers developed magnesium silicide nanoparticles for cancer-starvation therapy to deprive tumors of oxygen.
Tumors require a continuous supply of nutrients and oxygen to survive and grow. Interruption of the supply of oxygen or nutrients, tumors would wither and die. Tumor starvation is a well-known and promising therapeutic strategy. With cancer starvation, rapid rumor growth can be inhibited by stopping the blood supply that delivers oxygen and nutrients to the tumor. As a cancer-starving method, anti-angiogenic therapy has been one of the most effective clinical strategies for inhibiting tumor growth, whereby the supply of oxygen and nutrients into the tumor is interrupted. Although various deoxidants are available, it remains a challenge to design a drug that fulfills the various requirements of a cancer-starving agent. Such an agent must be biocompatible and must have a high deoxygenation efficiency and the characteristics of a long-term oxygen scavenger with tumor-tissue specificity. Moreover, it should be easily injectable by a syringe.
Prof. Bu et al. found that polyvinyl pyrrolidone (PVP)-modified magnesium silicide (Mg2Si ) nanoparticles can be used as a qualified deoxygenating agent (DOA) to realize specific tumor-starving therapy. The nanoparticles are prepared by a self-propagating high-temperature synthesis strategy.
Schematic diagram of Mg2Si nanoparticles serving as an intratumoral DOA for specific cancer-starving therapy.
According to their experiments, injecting the Mg2Si nanoparticles into tumors can block the delivery of oxygen and nutrition and consume oxygen in situ. Inorganic Mg2Si is a pH-sensitive material that is relatively stable at physiological pH but reacts with acids to generate the self-igniting gas silane (SiH4). Dissolved silane can react with oxygen to form silicon oxide (SiO2) aggregates. By this series of reactions, nanoparticulate Mg2Si can absorb dissolved and hemoglobin-bound oxygen to induce lasting hypoxia and tissue destruction in the acidic microenvironment of the tumors into which they are injected. The SiO2 aggregates formed by this reaction would also occlude blood vessels, further choking off oxygen and nutrient flow.
The low cost and easy-to-batch produced PVP-modified Mg2Si nanoparticles can be used as a DOA to starve tumors because of their biocompatibility, high deoxygenation efficiency, and tumor-tissue specificity. Their by-products, Mg2+ and SiO2, are also non-toxic and harmless, and can be safely metabolized and eliminated in vivo.
This work by Bu et al. is an excellent highlight of the potential impact of alternative strategies for killing tumors, and the Mg2Si nanoparticles offers a promising alternative cancer-starvation therapy.
Bu Wenbo, a Ph.D supervisor at Shanghai Key Laboratory of Green Chemistry and Chemical Process, School of Chemistry and Molecular Engineering, ECNU; and Shi Jianlin of State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, are the first writers of the paper “Magnesium silicide nanoparticles as a deoxygenation agent for cancer starvation therapy”.
The paper has attracted much attention since it was first published on line in Nature Nanotechnology，a monthly peer-reviewed scientific journal published by Nature Publishing Group, on January 9. Prestigious journals and news media including Chem, Chemical& Engineering News and PhysOrg havemade highlight reports and reviews on the work of Bu and his coworkers.