All Wrapped up: Stabilization of Enzymes within Single Enzyme Nanoparticles

Abstract

Enzymes are extremely useful in many industrial and pharmaceutical areas due to their ability to catalyze reactions with high selectivity. In order to extend their lifetime, significant efforts have been made to increase their stability using protein- or medium engineering as well as by chemical modification. Many researchers have explored the immobilization of enzymes onto carriers, or entrapment within a matrix, framework or nanoparticle with the hope of constricting the movement of the enzyme and shielding it from aggressive environments, thus delaying the denaturation. These strategies often balance three competing interests: (i) maintaining high enzymatic activity, (ii) ensuring good long-term stability against temperature, dehydration, organic solvents, and or aggressive pH, and (iii) enabling a tuning or reversible switching of enzyme activity. In most cases, multiple enzymes will be contained within a single nanoparticle or matrix, but in recent years researchers have begun to wrap up individual enzymes within single enzyme nanoparticles (SENs). In these nanoparticles the enzyme is stabilized by a thin shell, typically a polymer, prepared either by in situ polymerization from the enzyme surface or by assembling a preformed polymer around it. Because of the increased control over the environment directly around the enzyme, and the possibility of more directly controlling substrate diffusion, many SENs show remarkable stability while retaining high initial activities even for quite fragile enzymes. Moreover, the activity of the enzyme can often be more easily fine-tuned by adjusting the layer properties. We postulate that this emerging field will offer exciting and elegant opportunities to both extend the catalytic lifetime of enzymes in aggressive solvents, temperatures and pH, and enable their activity to be switched on and off on demand by modulation of the outer material layer.

Modulating the Biofunctionality of Metal–Organic‐Framework‐Encapsulated Enzymes through Controllable Embedding Patterns

“…Zeolitic imidazolate framework-8 (ZIF-8), synthesized by linking Zn 2+ nodes and HmIM through strong ZnÀN bonds, [27,28] is the most widely used exoskeleton for in situ enzyme encapsulation because of its biocompatible synthesis conditions and relative low-cytotoxicity. [10,11,29] GOx and Cyt Cwere firstly encapsulated into ananoZIF-8 exoskeleton by ad en ovo embedding strategy. [30] We chose nanoZIF-8 as the exoskeleton as the nanoscale porous network allows short diffusion routes of the guest, and thus improves the catalytic efficiency of the encapsulated enzymes.T he as-synthesized GOx@ZIF-8 and Cyt C@ZIF-8 possessed the apparent color of the corresponding parent enzymes (Figure S1A, Supporting Information).…”

The Synthesis of a 2D Ultra‐Large Protein Supramolecular Nanofilm by Chemoselective Thiol–Disulfide Exchange and its Emergent Functions

“…Unlike previously reported surface‐immobilized molecules, the molecules encapsulated in the lysozyme–cysteine nanofilm could be further released from the nanofilm, which is important for a variety of applications, for example, glycemic control by insulin delivery for mellitus patients . The release function of the nanofilm came from the pore formation among closely packed oligomers inside the nanofilm (Figure a) .…”

Nanoarchitectonics of Biofunctionalized Metal–Organic Frameworks with Biological Macromolecules and Living Cells

“…At present, there is a strong desire to develop general methods for encapsulating bioactive molecules within protective exteriors to extend their lifetime, increase tolerance to organic solvents, and enhance the thermal stability. Previously, lifetime extension and denaturation protection of biomolecules have been achieved by creating single‐enzyme nanoparticles with thin shells, allowing for increased control over the environment . In this regard, the exploration of MOFs either as carriers or protective layers for 3D biomolecules is a rapidly emerging research area.…”

“…Previously, lifetime extension and denaturation protection of biomolecules have been achieved by creating singleenzyme nanoparticles with thin shells, allowing for increased control over the envi ronment. [21] In this regard, the exploration of MOFs either as carriers or protective layers for 3D biomolecules is a rapidly emerging research area.…”