Rational Design of Yolk-Shell CuO/Silicalite-1@mSiO₂ Composites for a High-Performance Nonenzymatic Glucose Biosensor

In this study, an interface coassembly strategy is employed to rationally synthesize a yolk-shell CuO/silicalite-1@void@mSiO₂ composite consisting of silicalite-1 supported CuO nanoparticles confined in the hollow space of mesoporous silica, and the obtained composite materials were used as a novel nonenzymatic biosensor for highly sensitive and selective detecting glucose with excellent anti-interference ability. The synthesis of CuO/silicalite-1@mSiO₂ includes four steps: coating silicalite-1 particles with resorcinol-formaldehyde polymer (RF), immobilization of copper species, interface deposition of a mesoporous silica layer, and final calcination in air to decompose RF and form CuO nanoparticles. The unique hierarchical porous structure with mesopores and micropores is beneficial to selectively enrich glucose for fast oxidation into gluconic acid. Besides, the mesopores in the silica shell can effectively inhibit the large interfering substances or biomacromolecules diffusing into the void as well as the loss of CuO nanoparticles. The hollow chamber inside serves as a nanoreactor for glucose oxidation catalyzed by the active CuO nanoparticles, which are spatially accessible for glucose molecules. The nonenzymatic glucose biosensors based on CuO/silicalite-1@mSiO₂ materials show excellent electrocatalytic sensing performance with a wide linear range (5-500 μM), high sensitivity (5.5 μA·mM^-1·cm^-2), low detection limit (0.17 μM), and high selectivity against interfering species. Furthermore, the unique sensors even display a good capability in the determination of glucose in real blood serum samples.