A CaO @Tannic Acid-Fe Nanoconjugate for Enhanced Chemodynamic Tumor Therapy.

Chemodynamic therapy (CDT) is an effective tumor treatment strategy in which Fe reacts with hydrogen peroxide (H O ) in tumor cells to produce highly toxic hydroxyl radical ( OH) through the Fenton reaction. However, the content of endogenous H O in cells is limited, and the reaction between Fe and H O is inefficient, greatly limiting the efficiency of the Fenton reaction and reducing the effectiveness of tumor treatment. Therefore, in this work, we designed and synthesized a new type of nano-system (CaO @TA-Fe ) for the enhanced CDT of tumors, in which the polyphenolic compound- tannic acid (TA) and Fe formed a TA-Fe nano-coating on the surface of calcium peroxide (CaO ) nanospherical aggregates. When the CaO @TA-Fe nanoconjugates reach the tumor site, the CaO contained in the nanoconjugates produces H O after disintegration in tumor cells, and the carried TA rapidly reduces Fe to Fe , solving the two major shortcomings in CDT of (1) insufficient content of H O in cancer cells, and (2) low catalytic efficiency of the Fenton reaction. Additionally, the OH produced in the Fenton reaction induces oxidative stress for the tumor cells, promoting the occurrence of the "calcium overload" process, and thereby accelerating the death of tumor cells. Experimental results in vitro and in vivo showed that CaO @TA-Fe nanoconjugates can effectively kill cancer cells and display an excellent tumor therapeutic effect. We believe that the CaO @TA-Fe nanoconjugates are a promising new nano-platform for highly effective tumor treatment.