Catalytic cascades obtained from the combination of nanozymes, which are nanomaterials with enzyme-like activity, and natural enzymes have drawn much attention for biosensing and biomedical applications. A key consideration in the development of cascade reaction systems is the integration of nanozymes with enzymes to boost the overall catalytic performance. Here, we report an efficient one-pot approach for the preparation of an enzyme− nanozyme hydrogel composite for cascade catalysis. Prussian blue (PB) nanoparticles (NPs) were prepared by using mild synthetic conditions in a cellulose-based hydrogel network in the presence of glucose oxidase (GOx), resulting in the simultaneous immobilization of PB NPs and active GOx in the hydrogel. This integrated system not only displays peroxidase-like activity relative to the PB NPs but also reveals an enhanced cascade catalytic performance for the colorimetric detection of glucose due to the proximity effect of the enzyme−nanozyme system within the hydrogel matrix. Compared to the analogue mixture with GOx in solution, the composite hydrogel shows enhanced glucose detection and improved stability. The developed colorimetric assay was successfully applied for the analysis of glucose in human serum samples, demonstrating its potential in clinical diagnosis. The versatility of this one-pot protocol holds promise for the development of different multienzyme systems, leading to efficient cascade catalysis for sensing applications.

Metal-coordination complexes are attracting increasing attention as supramolecular cross-linkers to develop polymeric hydrogel networks with tunable and dynamic mechanical properties. Nonetheless, the rational design of these materials is still hindered by the limited mechanistic understanding of how metal−ligand interactions influence the structure and properties of the hydrogel. Here, we report a detailed mechanistic investigation using nuclear magnetic resonance (NMR) spectroscopy combined with molecular dynamics (MD) simulations to explore the formation of cellulose-based hydrogels induced by coordination with paramagnetic Fe 3+ ions. We demonstrate how NMR paramagnetic relaxation enhancement can be used to probe the distances between the metal center and NMR active nuclei on the polymer chain, informing on the metal−ligand coordination network. Experimental results, together with supporting MD simulations, allow us to uncover a structuration of water around the cross-linked metals within the hydrogel, in addition to the establishment of different orientations of the chains governed by hydrogen bonds networks. Progress in understanding the gelation mechanism of metal-coordinated hydrogels will fuel their exploitation for a wide variety of biomedical applications.

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Laboratory determinations on children aged 6 to 10 years obtained over a 5-year period are analysed by a method described in detail for differentiating between children from exposed and control areas of Seveso, Italy. In the analysis, stratification is employed to distinguish the separate days of laboratory measurement. The analyses permit the study of differences based on all variables simultaneously as well as on each variable separately. Results are obtained for each individual year and for longer intervals of 2 successive years, 3 successive years, 4 successive years, and all 5 years. The results and some statistical aspects of the analysis are discussed.

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