A cascade sensing platform of glucose oxidase loaded Fe-MOF functionalized via boric acid modification and defect...

Of tunable porosity, high specific surface area and excellent stability, the metal-organic frameworks (MOFs) as nanozyme capably not only catalyze the bio-substrate but load the natural enzyme, so as for the cascade catalyzation achievement. However, the limited mass transfer rate and natural enzyme abscission of MOFs are still fatal for the practical application. Herein, taking P-aminobenzoic acid (PABA) as a pore-size regulator and boronic acid (BA) as the bio-affinity sorbent, BA-MIL-100(Fe)-PABA of enlarged pores and better affinity was acquired as the peroxidase to ensure the efficient mass transfer and enzyme protection. Via the thorough investigation, the maximum reaction rate of H₂O₂ catalyzation by BA-MIL-100(Fe)-PABA was up to 2.62 × 10^-7 M·s^-1 with $K_m$ as low as 0.357 mM, along with the LOD of 0.77 μM. Loading GOx, a cascade platform of GOx@BA-MIL-100(Fe)-PABA was subsequently obtained to detect the blood glucose stable-selectively, with the wide linear response range (0.025-1.5 mM) and the LOD of 0.017 mM. The recycled catalytic activity of the platform was better 68% during 12 cycles. A new method for constructing defective MOFs at room temperature was thus proposed to achieve an efficient mass transfer and a better bio-affinity for glucose detection with high sensitivity and selectivity, paving the way for more sensitive detection and advanced applications.