Carbon Nanoparticles-Fe(II) Complex for Efficient Tumor Inhibition with Low Toxicity by Amplifying Oxidative Stress.

Fe element is essential for human beings, but overdose of Fe leads to unwanted toxicity. However, overwhelming Fe accumulation in tumor cells could arouse strong oxidative stress for cancer therapy. Therefore, the fast and specific accumulation of Fe in tumor cells without systemic toxicity is critical for this purpose. Herein, we reported that carbon nanoparticles-Fe(II) complex (CNSI-Fe) could efficiently load Fe into tumor cells and inhibit the tumor growth with low toxicity in H22 tumor bearing mice. Upon intratumoral injection, CNSI-Fe only induced meaningful Fe increase in tumor to significantly inhibit the tumor growth with competitive efficiency to cis-dichlorodiammine platinum (II). Fe accumulation stimulated the hydroxyl radical generation and serious oxidative stress in tumor. Due to the lack of Fe accumulation in other tissues, CNSI-Fe was of low systemic toxicity to tumor bearing mice. With the clinical success of CNSI for decades, CNSI-Fe might be used for cancer therapy through "off label" use to benefit the patients immediately.