Novel enzyme cascade colorimetric nanosensing platform based on 3D diatomic nanozymes synergistically enhancing peroxidase-like activity for the detection of xanthine

Abstract

Abnormal xanthine (XA) levels could cause various diseases, making sensitive and reliable XA detection crucial for early diagnosis. In this study, novel enzyme cascade colorimetric nanosensing platform based on 3D PtAu/PCN/S-rGO diatomic nanozymes with peroxidase-like (POD-like) activity was designed and fabricated. The doping of S and P increased the electron transfer rate, and the synergy of 3D PCN/S-rGO carriers increased the POD-like activity of diatomic nanozymes. Additionally, an efficient enzyme cascade nanosensing platform XOD@3D PtAu/PCN/S-rGO for the colorimetric detection of XA was constructed by utilizing this nanocomposite as a carrier for immobilizing xanthine oxidase (XOD) which could effectively enhance cascade efficiency. The intermediate •OH was produced during the cascade reaction, and the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by •OH was catalyzed by the nanocomposites to form blue oxTMB, which increased the absorbance at 652 nm and thus generated a colorimetric signal for the detection of XA. The linear range of XA detection was 1.5–250 μM, and the limit of detection was 1.29 μM. This nanosensing platform exhibited significant reproducibility, specificity, and stability, making it suitable for detecting XA in real human blood samples. Therefore, this enzyme cascade colorimetric diatomic nanosensing platform has potential applications for the detection of XA and other biomarkers in actual clinical samples.