Flexible Modulation of CO-Release Using Various Nuclearity of Metal Carbonyl Clusters on Graphene Oxide for Stroke Remediation

Utilizing the size-dependent adsorption properties of ruthenium carbonyl clusters (Ru-carbon monoxide (CO)) onto graphene oxide (GO), a facile CO-release platform for in situ vasodilation as a treatment for stroke-related vascular diseases is developed. The rate and amount of formation of the CO-release-active Ru-II(CO)(2) species can be modulated by a simple mixing procedure at room temperature. The subsequent thermally induced oxidation of Ru-II(CO)(2) to RuO2 on the GO surface results in the release of CO. Further modulation of thermal and CO-release properties can be achieved via a hybridization of medium- and high-nuclearity of Ru-CO clusters that produces a RuO2/Ru-II(CO)(2)/Ru-6-CO-GO composite, where Ru-6-CO-GO provides a photothermally activated reservoir of Ru-II(CO)(2) species and the combined infrared absorption properties of GO and RuO2 provides photothermal response for in situ CO-release. The RuO2/Ru-II(CO)(2)/Ru-6-CO-GO composite does not produce any cytotoxicity and the efficacy of the composite is further demonstrated in a cortical photothrombotic ischemia rat model.