Air-Derived Inhibitor of Nanozymes.

Nanozymes are functional nanomaterials with enzyme-mimicking activities, which have found wide applications in various fields. Investigation on nanozyme inhibitors not only helps to apply nanozymes in a controlled manner but also deepens our insight into the catalysis mechanism. Herein, we report an inorganic ion inhibitor, HCO3-, which can significantly inhibit the alkaline phosphatase-mimicking activities of Ce6 cluster-based metal-organic framework (Ce-MOF) nanozymes. The inhibition of adsorption of the negatively charged fluorescence sodium on Ce6 clusters in Ce-MOF nanoparticles (NPs) by HCO3- proves that HCO3- ions occupy and deactivate Ce6 clusters (i.e., catalytic active sites), leading to the activity inhibition of Ce-MOF nanozymes. Tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) buffer is widely employed as the alkaline reaction medium. HCO3- ions can be formed in Tris-HCl buffer through adsorption of CO2 in the air during storage in a sealed tube, which significantly inhibits the activity of Ce-MOF nanozymes. To our knowledge, this study is the first to demonstrate an air-derived inhibitor of nanozymes.