Acetaminophen sensor based on the oxidase-like activity and interference self-elimination ability of chondroitin sulfate-modified platinum nanozyme

Abstract

Platinum (Pt) nanozymes have drawn increasing attention in colorimetric sensors due to their remarkable oxidase-like activity. However, some antioxidant substances such as ascorbic acid (AA) will reduce the chromophore formed and interfere with the results of Pt nanozymes-based colorimetric sensors. Thus, chondroitin sulfate modified platinum nanozyme (CS-PtNPs) has been presented, which exhibits both oxidase-like and ascorbate oxidase-like activities. CS-PtNPs have a lower Km value (0.0135 mм) than most of reported Pt nanozymes, suggesting an ultrahigh affinity toward 3, 3′, 5, 5′-tetramethylbenzidine (TMB) and the enhancement on oxidase-like activity promoted by CS. The oxidase-like activity of CS-PtNPs can be ascribed to the formation of O2•− from the activation of dissolved O2. What is noteworthy is that CS-PtNPs have also been confirmed as a new ascorbate oxidase mimic (Km value = 0.404 mм) which can catalyze the oxidation of ascorbic acid (AA) by dissolved O2 into dehydroascorbic acid (DHAA). Inspired by these, a colorimetric sensor has been practiced as a competitive method to detect acetaminophen (AP). The addition of AP and then increasing the concentration can lead to a color gradient change in CS-PtNPs-catalyzed TMB system. More significantly, AA interference in AP detection can be eliminated by the ascorbate oxidase-like activity of CS-PtNPs. In experimental measurements, AP in effervescent tablets containing AA can be successfully detected with satisfactory results.