Polypyrrole Coating Eightfold Helical Wells-Dawson POMs based Cu-FKZ Framework for Boosting Colorimetric Sensing

To explore novel colorimetric biosensor with highly sensibility and selectivity, a new Wells-Dawson type polyoxometelates (POMs) based metal-organic framework (MOF) with eightfold helix, [Cu9(FKZ)12(H2O)8][H3P2W18O62]2·4H2O (CuFKZP2W18) (HFKZ = 1-(2,4-difluorophenyl)-1,1-bis[(1H-1,2,4-triazol-1-yl)methyl] ethanol), were successfully synthesized, then polypyrrole (PPy) were introduced to fabricate CuFKZP2W18/PPy(n) nanocomposites (n = 7%, 15%, 30%) via a facile ‘in situ’ oxidation polymerization process. All results indicate that CuFKZP2W18/PPy(15%) as the colorimetric biosensor exhibits the lowest limit of detection (0.07 μM towards H2O2 and 0.627 μM to ascorbic acid), the smallest Km value (0.106 mM for H2O2 and 0.042 mM for o-phenylenediamine) and the highest sensitivity (0.0227 1/μM towards H2O2 and 0.0025 1/μM to ascorbic acid) compared to most reported enzyme mimetics, to the best our knowledge.