Catalytic Activity, Stability, and Loading Trends of Alcohol Dehydrogenase Enzyme Encapsulated in a Metal–Organic Framework

Abstract

Recently, it has been shown that enzyme encapsulation inside metal–organic frameworks (MOFs) can increase enzyme activity and serve as protection from adverse environmental conditions. Little is understood about how the enzymes move into and are held inside the MOFs although it is believed that intermolecular forces between the MOF and the enzyme cause it to be held in place. If this process can be better understood, it can have dramatic implications on the cost-effectiveness and implementation of enzyme–MOF complexes. This is of specific importance in the medical sector for protein therapy and the industrial sector where enzyme use is expected to increase. Herein, we synthesized alcohol dehydrogenase (ADH) and PCN-333 to study encapsulation, stability, and enzyme activity to expand the knowledge of our field and offer a potential improvement to a synthetic route for biofuel synthesis. From this, we found a correlation between the concentration of a buffer and the loading of an enzyme, with surprising loading trends. We conclude that the buffer solution decreases interactions between the enzyme and MOF, supporting conventional theory and allowing it to penetrate deeper into the structure causing higher enzyme loading while allowing for excellent stability over time at various pH values and temperatures and after multiple reactions. We also observe new trends such as a rebounding effect in loading and “out-of-bounds” reactions.

Insights into the Interaction between Immobilized Biocatalysts and Metal–Organic Frameworks: A Case Study of PCN-333

“… 51 Recent publications have reported the successful immobilization of different enzymes within the pore network of PCN-333, including horseradish peroxidase (HRP), 51 cytochrome c (Cyt c), 51 microperoxidase-11 (MP-11), 51 catalase (CAT), 52 superoxide dismutase (SOD), 52 and alcohol dehydrogenase (ADH). 53 In this study, we have selected two commercially available enzymes of different sizes for the immobilization experiments: lipase (3.0 × 4.0 × 5.0 nm 3 ) 54 and insulin (1.3 × 1.3 × 3.4 nm 3 ) 55 ( Figure 1 c). Lipase is a commercially important enzyme that catalyzes hydrolysis reactions, 56 and insulin is an important medical hormone responsible for regulating the concentration of glucose in blood plasma.…”

Stabilization of an enzyme cytochrome c in a metal-organic framework against denaturing organic solvents

“…Very early during our study, water has shown to be an ineffective media for cytochrome c diffusion into NU-1000. Since previous reports have shown that buffer concentration influences enzyme loading in a different system through the PSE technique ( Phipps et al., 2020 ), we first explored encapsulation conditions for obtaining the cyt c @NU-1000 composite using Tris buffer at four different concentrations (0.00 M, 0.25 M, 0.50M, and 0.90 M). Prior to assessing the composites’ activities, we examined the structural integrity of the resultant materials.…”

Screen‐printing of nanocube‐based flexible microchips for the precise biosensing of ethanol during fermentation

“…All electrochemical measurements, including cyclic voltammetry (CV) chronoamperometry and electrochemical impedance spectroscopy (EIS), were performed on an electrochemical workstation (CHI 660E, Shanghai Chenhua Instrument Co., Ltd., China). Although we have tested the intrinsic resistance of AuNPs/NFPBA and NFPBA through BDS, considering that the biosensor was working in buffer, EIS was further applied to investigate the resistance of electron transfer ( R ct ) in solution 40 . EIS characterization was carried out in the presence of 5 mM [Fe(CN) 6 ] 3−/4− solution containing 0.1 M KCl, the frequency ranges were also from 0.01 Hz to 10 MHz.…”