Catalytic Duo Combats Blood Clots

Blood clots that form on implanted medical devices such as catheters and heart valves can curtail the lifetimes of the devices and possibly lead to health complications. Antithrombotic agents could prevent such clots, but scientists have yet to find a suitable way to provide a long-lasting, steady supply of those agents. As a possible solution, Teng Xue, Xiangfeng Duan, and Yu Huang of UCLA; Mark E. Meyerhoff of the University of Michigan; and coworkers have developed a catalytic system that generates the antithrombotic agent nitroxyl (HNO) from species commonly found in blood (Nat. Commun. 2014, DOI: 10.1038/ncomms4200). The system consists of the enzyme glucose oxidase and the molecular catalyst hemin, both attached to graphene. Glucose oxidase catalyzes the oxidation of glucose, a reaction that generates a local supply of hydrogen peroxide. Hemin then uses hydrogen peroxide to oxidize l-arginine to form nitroxyl. The researchers embedded the catalytic system in a polymer film and showed that platelets don’t adhere to the film after three days in blood plasma. Such films could be used as long-lasting coatings for medical devices, the researchers propose.