Enzymes-Nanoparticle Conjugates

The product of the combination of nanoparticles and enzymes forms a molecular hybrid that combines the properties of enzymes and nanoparticles. Typically, such complexes are prepared with the aim of altering the physicochemical properties of the enzyme. Relying on rich experience in nanoparticle modification, CD Bioparticles provides customers with comprehensive enzyme-nanoparticle conjugation strategies. We specialize in applying advanced conjugation techniques to custom develop biomolecules with diverse polymer architectures, including polymer chains, polymer topologies, and conjugated structures. Greater scalability and lower production costs are possible with our nanoparticles bioconjugation services.

Introduction to Enzymes-Nanoparticle Conjugates

Enzymes are known for their high specificity, making them efficient biocatalysts that are environmentally friendly. In clinical applications, many proteins face solubility and stability challenges. This makes these proteins easily degraded in the body and lose their function. In addition, proteins also have disadvantages such as short existence time in vivo and easy triggering of immunogenic reactions. Since enzymes are mainly composed of proteins, their applications are limited by the properties of proteins. In addition, enzymes are very sensitive to non-physiological conditions such as extreme pH, high temperature, or detergents, which further limits their applications. To increase the stability of enzymes, a common strategy is to covalently bind enzymes to inert, biocompatible, water-soluble nanoparticles. Many classes of polymeric nanoparticles have been studied, including polyethylene glycol (PEG), hyaluronic acid, dextran, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), hydroxyethyl starch (HES), Polyethyleneimine (PEI) and polyphosphate. These polymers provide stability to enzymes by shielding and protecting them from denaturing conditions.

Figure 1. Enzymatic bioconjugation of nanoparticles.(Walper SA, et al.; 2015)

Currently, the most commonly used polymer is polyethylene glycol approved by the Food and Drug Administration (FDA). Polyethylene glycol can form a water layer around the enzyme, making the enzyme soluble and active in polar organic solvents. In addition, the steric hindrance of PEG can prevent the dissociation and self-polymerization of the enzyme. In enzyme-polymer conjugates, the polymer reacts with specific amino acids on the enzyme through its functional groups. It is especially important that the polymer has electrophilic functional groups that can react with nucleophilic amino acids such as cysteine, lysine, arginine, serine, threonine, or tyrosine. Under physiological conditions, enzymes form covalent bonds with polymers, resulting in enzyme-polymer conjugates. This enzyme-polymer conjugate can enhance the industrial application potential of enzymes. For example, polymer linkages can better protect enzymes from degradation and thus have a longer half-life in the body than native enzymes. In addition, immobilizing enzymes on nanoparticles also demonstrates a promising strategy for enzyme attachment. In addition to enhancing enzyme activity and stability, this also opens up new vistas for biocatalysis.

The specific features of enzymes-nanoparticle conjugates include:

• Enhanced stability and activity: Nanoparticles have protective properties that protect enzymes from denaturation under harsh conditions such as high temperature or extreme pH. This enhanced stability allows the enzyme to remain active for extended periods of time.
• Improved catalytic efficiency: Enzyme-nanoparticle complexes showed higher catalytic efficiency compared to free enzymes. The high surface area of nanoparticles facilitates increased enzyme loading, resulting in improved substrate binding and reaction rates.
• Tunable substrate specificity: By modifying the nanoparticle surface, researchers are able to influence the substrate specificity of the enzyme in the enzyme-nanoparticle complex. This opens up opportunities to tailor enzyme-catalyzed reactions for specific applications.
• Versatility: Enzyme-nanoparticle complexes can carry multiple enzymes with complementary activities. This enables them to catalyze different reactions sequentially or simultaneously, for use in complex processes.
• Targeted delivery: Nanoparticles can be functionalized to deliver enzymes to specific locations within biological systems. Such targeted delivery improves efficiency and reduces non-specific effects, which is of great value in drug delivery and therapeutic applications.
• Bioimaging: Nanoparticles often have intrinsic imaging properties, such as fluorescence or magnetic resonance contrast. Immobilizing enzymes on these nanoparticles enables simultaneous imaging and enzyme activity monitoring.
• Biosensing: Enzyme-nanoparticle complexes can be used to develop highly sensitive biosensors. Enzyme catalytic activity combined with nanoparticle-based signal amplification increases the detection range of target molecules.
• Biocatalysis in non-biological environments: Enzyme-nanoparticle complexes can function in non-biological environments, such as organic solvents, extending their application to chemical synthesis and other fields.
• Renewable and reusable: Enzyme-nanoparticle complexes are designed to be easily separated from reaction mixtures for regeneration and reusability, especially for industrial processes.
• Synergistic effects with nanoparticle properties: Depending on the material, size, and surface properties of the nanoparticles, enzyme-nanoparticle complexes may exhibit synergistic effects, such as enhanced thermal stability or altered substrate binding properties.

Our Featured Services

• Construction of Nanoscale Biocatalysts

The formation of nanoscale biocatalysts can be achieved by the immobilization of enzymes, using traditional methods such as covalent coupling or embedding to generate hybrid units containing individual enzymes, or by combining them with nanocarriers. The main advantage of nanoscale biocatalysts lies in their high enzyme loading per unit weight, which enables them to exhibit excellent catalytic performance. We provide customized nanoscale biocatalyst development services, including single-enzyme nanogels (SENs), polymeric micelles, dendritic nanoparticles, giant amphiphiles, reverse micelles, polyion complex vesicles, and MOF-enzyme nano hybrids, etc.

• Microstructured Enzyme-Polymer Assemblies

Compared with macroscopic structures, micron-scale polymers usually exhibit lower diffusion problems and better scale-up capabilities, making them one of the best choices in biocatalytic bioreactor design. At CD Bioparticles, we specialize in the polymeric hydrogels, layer-by-layer assembled enzyme microparticles, cross-linked polymers, and enzyme hybrids prepared by electrospun polymeric fibers. Our microstructured enzyme-polymer assembly services include: custom enzyme hydrogel micromixtures, custom enzyme-polymer microhybrids, custom cross-linked enzyme-polymer conjugates, and custom enzyme-polymer fiber hybrids.

• Integrated Assembly of Enzymes and Polymers

CD Bioparticles also focuses on applying macrostructured polymers to enzyme immobilization platforms to form monolithic and continuous films. The size of these materials endows the blends with superior mechanical properties, extending their range of applications. Our macrostructural enzyme-polymer assembly services include: customization of polymer-enzyme hybrids and enzyme-polymer thin films.

The applications of enzymes-nanoparticle conjugates include:

• Enzyme-polymer nanocomposites: Enzymes can be immobilized on the surface of polymers, encapsulated in hollow structures, or embedded in porous polymer networks. These materials have had a dramatic impact on diverse applications such as biocatalysis, bioseparation, imaging, biosensing, in vitro biotransformation, drug delivery, and therapy.
• Biocatalysis applications: In the field of biocatalysis, polymers provide suitable anchoring sites for enzymes (widely used in heterogeneous biocatalysis), and can also actively participate in regulating the properties of enzymes to achieve synergistic enhancement effects of catalytic systems.
• Single-enzyme nanogels: Single-enzyme nanogels, as a promising technology, encapsulate enzymes individually in thin hydrogel layers. This core-shell structure is synthesized in situ, in which biomolecules are preserved in the core region, while the polymer acts as a protective shell. Typically, these structures exhibit catalytic properties similar to natural enzymes.

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References

1. Ding S, et al.; Increasing the activity of immobilized enzymes with nanoparticle conjugation. Curr Opin Biotechnol. 2015, 34:242-50.
2. Huang Y, et al.; Nanozymes: Classification, Catalytic Mechanisms, Activity Regulation, and Applications. Chem Rev. 2019, 119(6):4357-4412.
3. Walper SA, et al.; Enzymatic bioconjugation of nanoparticles: developing specificity and control. Curr Opin Biotechnol. 2015, 34:232-41.