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

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 m\M) 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 center dot- 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 m\M) 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.

Automated summary

Platinum nanozymes have been modified with chondroitin sulfate to exhibit lower Km value and both oxidase-like and ascorbate oxidase-like activities. This modification allows for potential applications in detecting acetaminophen with the ability to eliminate interference from ascorbic acid.