Highly Stable Iron Carbonyl Complex Delivery Nanosystem for Improving Cancer Therapy

Metal carbonyl complexes can readily liberate carbon monoxide (CO) in response to activation stimulus. However, applicability of metal carbonyl complexes is limited because they are unstable under natural ambient conditions of moisture and oxygen. Reported here is the rational design of an iron carbonyl complex delivery nanosystem for the improvement of cancer therapy. We demonstrated that iron pentacarbonyl (Fe­(CO)₅) can be encapsulated into the cavity of a Au nanocage under an oxygen-free atmosphere and then controllably form iron oxide on the surface of the Au nanocage under aerobic conditions. The formation of iron oxide efficiently avoids the leakage and oxidation of the caged Fe­(CO)₅. The resulting nanomaterial exhibits excellent safety, biocompatibility, and stability, which can be specifically activated under near-infrared (NIR) irradiation within the tumor environment to generate CO and iron. The released CO causes damage to mitochondria and subsequent initiation of autophagy. More importantly, during autophagy, the nanomaterial that contains iron and iron oxide can accumulate into the autolysosome and result in its destruction. The produced CO and iron show excellent synergistic effects in cancer cells.