Hemin-Block Copolymer Micelle as an Artificial Peroxidase and Its Applications in Chromogenic Detection and Biocatalysis

Abstract

Following an inspiration from the fine structure of natural peroxidases, such as horseradish peroxidase (HRP), an artificial peroxidase was constructed through the self-assembly of diblock copolymers and hemin, which formed a functional micelle with peroxidase-like activity. The pyridine moiety in block copolymer poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP) can coordinate with hemin, and thus hemin is present in a five-coordinate complex with an open site for binding substrates, which mimics the microenvironment of heme in natural peroxidases. The amphiphilic core-shell structure of the micelle and the coordination interaction of the polymer to the hemin inhibit the formation of hemin μ-oxo dimers, and thereby enhance the stability of hemin in the water phase. Hemin-micelles exhibited excellent catalytic performance in the oxidation of phenolic and azo compounds by H2O2. In comparison with natural peroxidases, hemin-micelles have higher catalytic activity and better stability over wide temperature and pH ranges. Hemin-micelles can be used as a detection system for H2O2 with chromogenic substrates, and they anticipate the possibility of constructing new biocatalysts tailored to specific functions.

Enhancing the Activity of Peptide-Based Artificial Hydrolase with Catalytic Ser/His/Asp Triad and Molecular Imprinting

“…[9][10][11][12][13][14][15] Peptide-based nanofibers that are built from peptides self-assembly is an ideal supramolecular framework for constructing artificial enzymes because the building blocks of peptides are amino acid residues and the driving forces for self-assembly are non-covalent interactions, which share many characteristics with natural proteins. 16,17 Furthermore, the nanofibers built through non-covalent interactions can form the amphiphilic architecture, in which the functional groups are in close proximity and establish additional non-covalent interactions that contribute to the catalytic activity of nanofibers.…”

Artificial Peroxidase/Oxidase Multiple Enzyme System Based on Supramolecular Hydrogel and Its Application as a Biocatalyst for Cascade Reactions

“…An artificial peroxidase was used instead of HRP, which was an effective measure to keep the enzymatic activity at a high level. 23 The complex micelles and oxidases were encapsulated in the hydrogels, in this way, the diffusion of Many attempts have been made to prepare tough hydrogels with inner crosslinking. 41,42 However, the crosslinking process is always time-consuming and has negative effect on the enzymatic activity.…”

“…23 Large amounts of H 2 O 2 were required during the oxidation reactions. However, chemical synthesis of H 2 O 2 is not environmentally friendly, and high concentration of H 2 O 2 may lead to inactivation of peroxidases.…”

Directed motion of a polyelectrolyte micelle along tethered chains of oppositely charged polyelectrolyte brush

“…The understanding of the complexation of micelles or proteins with oppositely charged polyelectrolyte (PE) brushes is of fundamental importance in various scientific fields especially in the design of efficient artificial enzymes for environmental, industrial, medical, and biosensing applications . The reason is that the immobilization through complexation of micelles (artificial enzymes) or proteins (natural enzymes) into spherical or planar brushes enhances the stability in various environments and induces enzyme selectivity because substrates with different sizes have different diffusion characteristics into immobilization media and consequently different performances in catalytic reactions …”