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Development of a Uricase-Free Colorimetric Biosensor for Uric Acid Based on PPy-Coated Polyoxometalate-Encapsulated Fourfold Helical Metal–Organic Frameworks

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journal contribution
posted on 13.02.2020, 16:46 by Ying-Ying Wang, Hai-Feng Zhang, Dong-Hui Wang, Ning Sheng, Gong-Guo Zhang, Ling Yin, Jing-Quan Sha
Developing a new cost-effective and reliable approach used for the detection of uric acid (UA) with no requirement of uricase is still very challenging. Herein, an easily realized, cost-effective, and uricase-free approach is reported for selective colorimetric biosensing of UA utilizing polypyrrole (PPy)-coated polyoxometalate-encapsulated fourfold helical metal–organic frameworks Ag5[bimt]2[PMo12O40]·2H2O (Ag5PMo12) as a monolithic peroxidase mimic. It is demonstrated that the as-obtained Ag5PMo12@PPy possesses excellent peroxidase-like activity originated from the synergistic effect to induce catalytic oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to green oxTMB in the presence of H2O2. Then, the green oxTMB can be selectively converted to colorless TMB induced by UA; thus, UA can inhibit the catalytic oxidation of TMB. Based on these results, a uricase-free colorimetric biosensor for UA is achieved with a linear detection range of 1–50 μM and a detection limit of 0.47 μM. More importantly, the developed biosensor is suited for simple-operated and good reliable UA detection in clinical samples, showing promising application ability in clinical diagnosis and relative fields.