Tellurium-Based Polymeric Surfactants as a Novel Seleno-Enzyme Model with High Activity

Glutathione peroxidase-like nanozymes: mechanism, classification, and bioapplication

The field of nanozymes is developing rapidly. In particular, glutathione peroxidase (GPx)-like nanozymes, which catalytically reduce H₂O₂/organic hydroperoxides to H₂O/alcohols, have attracted considerable attention. GPx-like nanozymes are powerful antioxidant enzymes known to combat oxidative stress. They have broad applications, including cytoprotection, anti-inflammation, neuroprotection, tumor therapy, and anti-aging. Although much progress has been made, GPx-like nanozymes have not been well discussed or fully reviewed as other nanozymes. This review aims to summarize recent advances on GPx-like nanozymes from the vantage point of mechanism, classification, and bioapplication. Future prospects for advancing their design and application are also discussed.

Whole-Cell-Based Photosynthetic Biohybrid Systems for Energy and Environmental Applications

With the increasing awareness of sustainable development, energy and environment are becoming two of the most important issues of concern to the world today. Whole-cell-based photosynthetic biohybrid systems (PBSs), an emerging interdisciplinary field, are considered as attractive biosynthetic platforms with great prospects in energy and environment, combining the superiorities of semiconductor materials with high energy conversion efficiency and living cells with distinguished biosynthetic capacity. This review presents a systematic discussion on the synthesis strategies of whole-cell-based PBSs that demonstrate a promising potential for applications in sustainable solar-to-chemical conversion, including light-facilitated carbon dioxide reduction and biohydrogen production. In the end, the explicit perspectives on the challenges and future directions in this burgeoning field are discussed.

One-pot synthesis of biomimetic glutathione peroxidase with temperature responsive catalytic behaviors

Excessive reactive oxygen free radicals (ROS) are the main cause of various oxidative diseases. It is of great significance to develop antioxidant drugs that can intelligently regulate free radical concentrations. The biomimetic simulation of glutathione peroxidase (GPx) can provide an important theoretical basis for the development of antioxidant drugs. In order to explore a simple and efficient strategy for constructing biomimetic GPx, a microgel biomimetic GPx (PNTegel) with temperature responsive catalytic activity was prepared by a one-pot synthesis method. The PNTegel, with typical enzymatic catalytic characteristics, exhibited a maximum catalytic activity at 37 °C (υ₀ = 11.51 mM min⁻¹). The investigation of the catalytic mechanism of PNTegel suggested that the binding of different hydrophobic substrates to PNTegel was altered by the change of hydrophobicity of poly(N-isopropylacrylamide) (PNIPAM) in the microgel scaffold of PNTegel during the temperature response process. The change of hydrophobicity was the main factor for regulating the catalytic activity of PNTegel, which resulted in a temperature responsive catalytic behavior of PNTegel. This new strategy for the simple and efficient construction of biomimetic GPx by a one-pot method provides important theoretical support for exploring the preparation of highly effective antioxidant drugs.

A microgel-based biomimetic glutathione peroxidase with temperature responsive catalytic behavior is synthesized by integrating atom transfer radical polymerization (ATRP) technology into one-pot synthesis.

Construction of a smart microgel glutathione peroxidase mimic based on supramolecular self-assembly

In an effort to construct smart artificial glutathione peroxidase (GPx) featuring high catalytic activity in an efficient preparation process, an artificial microgel GPx (PPAM-ADA-Te) has been prepared using a supramolecular host-guest self-assembly technique. Herein, 6,6'-telluro-bis(6-deoxy-β-cyclodextrin) (CD-Te-CD) was selected as a tellurium-containing host molecule, which also served as the crosslinker for the scaffold of the supramolecular microgel. And an adamantane-containing block copolymer (PPAM-ADA) was designed and synthesized as a guest building block copolymer. Subsequently, PPAM-ADA-Te was constructed through the self-assembly of CD-Te-CD and PPAM-ADA. The formation of this self-assembled construct was confirmed by dynamic light scattering, NMR, SEM and TEM. Notably, PPAM-ADA-Te not only exhibits a significant temperature responsive catalytic activity, but also features the characteristic saturation kinetics behaviour similar to that of a natural enzyme catalyst. We demonstrate in this paper that both the hydrophobic microenvironment and the crosslinker in this supramolecular microgel network played significant roles in enhancing and altering the temperature responsive catalytic behaviour. The successful construction of PPAM-ADA-Te not only provides a novel method for the preparation of microgel artificial GPx with high catalytic activity but also provides properties suitable for the future development of intelligent antioxidant drugs.

Hemin-block copolymer micelle as an artificial peroxidase and its applications in chromogenic detection and biocatalysis

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.

A glimpse on biological activities of tellurium compounds

Tellurium is a rare element which has been regarded as a toxic, non-essential trace element and its biological role is not clearly established to date. Besides of that, the biological effects of elemental tellurium and some of its inorganic and organic derivatives have been studied, leading to a set of interesting and promising applications. As an example, it can be highlighted the uses of alkali-metal tellurites and tellurates in microbiology, the antioxidant effects of organotellurides and diorganoditellurides and the immunomodulatory effects of the non-toxic inorganic tellurane, named AS-101, and the plethora of its uses. Inasmuch, the nascent applications of organic telluranes (organotelluranes) as protease inhibitors and its applications in disease models are the most recent contribution to the scenario of the biological effects and applications of tellurium and its compounds discussed in this manuscript.

Incorporation of glutathione peroxidase active site into polymer based on imprinting strategy

Glutathione peroxidase (GPx, EC 1.11.1.9) is a key enzyme involved in scavenging of reactive oxygen species in biological system. For developing an efficient GPx-like antioxidant, catalytically necessary amino acid derivatives which located near the GPx active center were prepared as functional monomers. Via predetermined imprinting with substrate glutathione (GSH), a polymer-based GPx mimic with a similar structure of catalytic center of natural GPx was developed, and it demonstrated high-catalytic efficiency and substrate specificity. The imprinting polymer (I-PEM) exhibits GPx-like activity about three times higher than that of 2-SeCD, a cyclodextrin-based GPx mimic. The detailed studies on kinetics revealed that not only the substrate binding but also positional arrangement of reacting groups contribute significantly to the catalytic efficiency of the peroxidase model.