Size-Tunable Metal–Organic Framework-Coated Magnetic Nanoparticles for Enzyme Encapsulation and Large-Substrate Biocatalysis

Abstract

Immobilizing enzymes on nanoparticles (NPs) enhances the cost-efficiency of biocatalysis; however, when the substrates are large, it becomes difficult to separate the enzyme@NP from the products while avoiding leaching or damage of enzymes in the reaction medium. Metal–organic framework (MOF)-coated magnetic NPs (MNPs) offer efficient magnetic separation and enhanced enzyme protection; however, the involved enzymes/substrates have to be smaller than the MOF apertures. A potential solution to these challenges is coprecipitating metal/ligand with enzymes on the MNP surface, which can partially bury (protect) the enzyme below the composite surface while exposing the rest of the enzyme to the reaction medium for catalysis of larger substrates. Here, to prove this concept, we show that using Ca2+ and terephthalic acid (BDC), large-substrate enzymes can be encapsulated in CaBDC-MOF layers coated on MNPs via an enzyme-friendly, aqueous-phase one-pot synthesis. Interestingly, we found that using MNPs as the nuclei of crystallization, the composite size can be tuned so that nanoscale composites were formed under low Ca2+/BDC concentrations, while microscale composites were formed under high Ca2+/BDC concentrations. While the microscale composites showed significantly enhanced reusability against a non-structured large substrate, the nanoscale composites displayed enhanced catalytic efficiency against a rigid, crystalline-like large substrate, starch, likely due to the improved diffusivity of the nanoscale composites. To our best knowledge, this is the first report on aqueous-phase one-pot synthesis of size-tunable enzyme@MOF/MNP composites for large-substrate biocatalysis. Our platform can be applied to immobilize other large-substrate enzymes with enhanced reusability and tunable sizes.

Protocol for resolving enzyme orientation and dynamics in advanced porous materials via SDSL-EPR

“…Lysozyme is a good model because both large (∼μm) and small (∼nm) size substrates can be catalyzed by this enzyme ( Vocadlo et al., 2001 , Kao et al., 2014 ). Meanwhile, MOFs/COFs are advanced porous platforms for enzyme encapsulation ( Howarth et al., 2016 , Majewski et al., 2017 , Drout et al., 2019 , Wang et al., 2020 , Gkaniatsou et al., 2017 , Lyu et al., 2014 , Lian et al., 2017 , Li et al., 2020 , Farmakes et al., 2020 , Neupane et al., 2019 ). Note that, a unique feature of SDSL-EPR is that it is immune of the background matrices (under low water volume; see below) ( Pan et al., 2021a ).…”

Advances in Functional Metal‐Organic Frameworks Based On‐Demand Drug Delivery Systems for Tumor Therapeutics

“…Another strategy for using the temperature responses of MOFs is to modify their porous surface with thermo‐responsive polymers, e.g., poly(N‐isopropyl acrylamide) (PNIPAM), which possesses a reversible lower critical solution temperature (LCST) phase transition from a hydroswollen state to a shrunken dehydrated state. [ 71–76 ] In other words, this polymer is hydrophilic and dissolves in water when the temperature is below the T c at ≈32 °C, yet it also forms aggregates. [ 77–79 ] Using this unique feature, Karmakar et al ( Figure 5 ) reported that a chromium‐based MOF (MIL‐101) modified by PNIPAM exhibited thermo‐responsive water capture and release behavior.…”

“…Due to the complicated syntheses and harsh conditions, the degradation of the drug exhibits great potential applications. [ 137–141 ] In this regard, Kim et al reported an enzyme‐responsive MOF composed of Zr‐based porphyrinic MOFP (CN224 MOF) and HA. [ 142 ] The MOF was coated by enzyme‐responsive HA through multivalent coordination bonding between the Zr cluster and carboxylic acids of HA.…”

Preparation of One‐Pot Immobilized Lipase with Fe3O4 Nanoparticles Into Metal‐Organic Framework For Enantioselective Hydrolysis of (R,S)‐Naproxen Methyl Ester

“…Moreover, the potential application of magnetic porous MOFs as the support for enzyme immobilization needs to be explored. To date, there are only a few reports on the preparation of magnetic ZIF biocomposites [7,10,13,21,24–26] . For example, Ricco co‐workers have prepared the enzyme horseradish peroxidase and iron oxide magnetic nanoparticles in a one‐pot synthesis and performed reusable biocatalysts [10] .…”