It was first characterized by the surface charge differences that have been elevated from the default OA nanozyme and the binding with the histamine, evidence for the proposed strategies. (Figure ). To prevent the argument with other possibilities including radical scavenger-like activity of histamine, EPR analysis was conducted. The EPR signals are located with the same pattern in either OA nanozyme (with baseline, H2O2+DMPO) or OA nanozyme (with baseline) with histamine, demonstrating that histamine does not have radical scavenging activity, consistent with the previous reference . Therefore, the reduction in ABTS oxidation is not due to the radical scavenging activity of the substance but rather the initial shielding of the active sites of OA nanozyme (Figure ).