Enzyme Immobilization in MOF‐derived Porous NiO with Hierarchical Structure: An Efficient and Stable Enzymatic Reactor

Abstract

MOF‐derived porous NiO with hierarchical structure (MHNiO) was prepared based on thermolysis of Ni metal organic framework (Ni‐MOF), which was used as carrier for the immobilization of horseradish peroxidase (HRP) and cytochrome C (Cyt c). The pore size of MHNiO was tuned as 11.8 nm to match the size of free enzyme so as to depress the aggregation of the enzymes in the pore. Meanwhile, the hierarchical structure allowed the substrates concentrated in the vicinity of the enzymes. The obtained enzymatic reactors exhibited better thermal stability, storage stability and reusability. For example, over 83 % of its original activity after 1 h incubation at 70 °C could be remained compared to 18.1 % or 38.4 % remained activity of free HRP and Cyt c, respectively; After 12 cycles of use, over 53 % of original catalytic activity of both the enzymatic reactor could be maintain. The enzymatic kinetic data (Km, Vmax, kcat) and thermodynamic data (Ka, ΔH, ΔS and ΔG) indicated that the improved catalytic performance was attributed to the affinity, selectivity and binding of enzyme to substrate. The two enzymatic reactors could be applied in the fast degradation of 2,4‐dichlorophenol and rifaximin in artificial wastewater, a complete degradation of 2 mg ⋅ mL−1 of 2,4‐dichlorophenol or 20 μg ⋅ mL−1 of rifaximin was achieved in only 20 min.

Hydrogel Paper-Based Analytical Devices: Separation-Free In Situ Assay of Small-Molecule Targets in Whole Blood

“…The hydrogel with an egg-box network structure is triggered by Ca 2+ produced by the reaction of CH 3 COOH with CaCO 3 in the sol solution. As the alginate network grows, enzymes GO x (6.0 nm × 5.5 nm × 7.7 nm) and HRP (4.4 nm × 4.4 nm × 6.8 nm) and TMB are encapsulated. The hydrodynamic diameter of tens of nanometers was estimated for TMB since 3,3′-diaminobenzidine (DAB), which has a similar structure to that of TMB, was estimated to have a hydrodynamic radius of tens of nanometers .…”

MOF‐Hosted Enzymes for Continuous Flow Catalysis in Aqueous and Organic Solvents

“…Furthermore, the separation of the catalyst from the product, a time‐consuming and costly process, is substantially accelerated for MOF‐embedded enzymes [6, 21] . Several proof‐of‐principle studies have demonstrated the potential MOF‐hosted enzymes, but so far studies were mostly limited to simple batch experiments [22–24] . Continuous‐flow experiments as required for technologically relevant applications have not yet been reported for enzymes infiltrated in MOF systems.…”

“…[6,21] Several proof-of-principle studies have demonstrated the potential MOF-hosted enzymes, but so far studies were mostly limited to simple batch experiments. [22][23][24] Continuous-flow experiments as required for technologically relevant applications have not yet been reported for enzymes infiltrated in MOF systems. Tian et al reported a continuous flow reactor filled with MOF coated micelles containing the enzyme CALB.…”

In MOF eingebettete Enzyme für die kontinuierliche Durchflusskatalyse in wässrigen und organischen Lösungsmitteln

“…Darüber hinaus wird die Trennung des Katalysators vom Produkt – ein zeit‐ und kostenaufwendiger Prozess – bei in MOF eingebetteten Enzymen erheblich beschleunigt [6, 21] . Mehrere Proof‐of‐Principle‐Studien haben das Potenzial von in MOF eingebetteten Enzymen aufgezeigt, bislang waren die Studien jedoch meist auf einfache Batch‐Experimente beschränkt [22–24] . Experimente mit einem kontinuierlichen Durchfluss, wie sie für technologisch relevante…”