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.