Catalytically Active Enzyme-Based Nanoparticles for Cellular Modulation
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Abstract
Protein-based nanomedicine platforms are versatile application systems due to their biodegradability, biocompatibility and low toxicity. Especially the use of enzymes, which represent highly specific biocatalysts, is a promising challenge in therapeutic applications. These systems can offer the potential to intervene in cellular mechanisms and to manipulate them.
This PhD thesis presents a novel approach for the synthesis of catalytically active enzyme-based nanoparticles. The nanosystems consist solely of enzyme-polymer conjugates, where natural enzymes are covalently linked to the FDA-approved synthetic polymer polyethylene glycol. The preservation of the enzymatic activity was realized by mild PEGylation routes. For this, four different activated PEG chains were synthesized and used for the surface modification of lysozyme. Due to the design of a lipophilic biomaterial, an emulsion-based technique was used as particle preparation method, resulting in stable nanoparticles in a size range of 120–200 nm. This concept was applied to the development of peroxidase active nanoparticles for the modulation of reactive oxygen species (ROS). Three different peroxidases were used in their PEGylated form as active building blocks. It could be shown that the nanoparticle systems act both, extra- and intracellular as redox-active material, leading to the decrease of harmful ROS.
Furthermore, the design of an active dual-enzyme nanoparticle system was presented. The combination of two PEGylated enzymes in the emulsification evaporation method led to the creation of a cascade-performing particle system. The investigation of five various enzyme quantities within the particle system resulted in catalytically active nanoparticles with different substrate affinities and catalytic efficiencies.
This thesis provides, not only novel bio¬mimetic approaches to study cellular processes but also offer the potential to produce next-generation delivery and manipulation platforms for innovative applications in bio¬medical research.