Enzyme cascade signal amplification platform with immobilized xanthine oxidase on nanozymes exhibiting enhanced POD-like activity for ultrasensitive dual-mode detection of xanthine

Xanthine (XA) metabolic disorders cause many diseases, hence early and precise XA detection is essential. Herein, a dual-mode enzyme cascade nanosensing platform based on Au/FMZIF-rGO/PCN nanomaterial with dual-emissive and high peroxidase-like (POD-like) activity was devised. The rapid electron transfer between Fe, Mn and P elements and the formation of ZIF-rGO/PCN hybrid enhanced POD-like activity. Aggregation-induced emission (AIE) effect improved fluorescence intensity of AuNCs. Furthermore, utilizing the nanozyme to immobilize xanthine oxidase (XOD) also reduced intermediate product diffusion, improving cascade efficiency and platform detection & sdot;H2O2 was catalytically decomposed to generate center dot OH, lowering fluorescence intensity at 627 nm and oxidizing TMB to produce blue oxTMB. So, dual-mode nanosensing platform was constructed with linear ranges for ratio fluorescence and colorimetric detection of XA spanning 0.5-200 mu M and 0.5-300 mu M, respectively, and corresponding LODs of 0.11 and 0.24 mu M. The nanoplatform suggested promising potential for practical clinical detection of XA and other biomarkers.