A GO-Se nanocomposite as an antioxidant nanozyme for cytoprotection

Selenium-Based Nanozyme as Biomimetic Antioxidant Machinery

A self-assembly nanocomposite was designed to mimic intracellular enzymatic and non-enzymatic antioxidants-constituted antioxidant defense machinery. In this work, selenium nanocomponent served as one model to mimic antioxidant enzyme, whereas polydopamine was able to mimic non-enzymatic antioxidant biomolecule in living systems. With the excellent glutathione peroxidase-mimic capacity of selenium and the reducibility of polydopamine, this Se@pDA nanozyme could achieve synergetic antioxidative efficiency to protect cellular components against oxidative damage. The pneumonia model of mice further proved the potential of our nanocomposites for anti-inflammation therapy.

A label-free fluorescence assay for hydrogen peroxide and glucose based on the bifunctional MIL-53(Fe) nanozyme

A label-free nanozyme MIL-53(Fe) with the dual-function of catalyzing and emitting fluorescence was utilized for turn-on fluorescence detection of hydrogen peroxide and glucose. The proposed strategy provides a cost-effective, safe and sensitive method for the design and development of multiple enzyme cascade assays for various biomolecules.

Evaluation of the structure–activity relationship of carbon nanomaterials as antioxidants

Aim: To develop the potential application of carbon nanomaterials as antioxidants calls for better understanding of how the specific structure affects their antioxidant activity. Materials & methods: Several typical carbon nanomaterials, including graphene quantum dots and fullerene derivatives were characterized and their radical scavenging activities were evaluated; in addition, the in vitro and in vivo radioprotection experiments were performed. Results: These carbon nanomaterials can efficiently scavenge free radicals in a structure-dependent manner. In vitro assays demonstrate that administration of these carbon nanomaterials markedly increases the surviving fraction of cells exposed to ionizing radiation. Moreover, in vivo experiments confirm that their administration can also increase the survival rates of mice exposed to radiation. Conclusion: All results confirm that large, buckyball-shaped fullerenes show the strongest antioxidant properties and the best radioprotective efficiency. Our work will be useful in guiding the design and optimization of nanomaterials for potential antioxidant and radioprotection bio-applications.

Antioxidant activity of nanomaterials

Nanomaterials represent one of the most promising frontiers in the research for improved antioxidants. Some nanomaterials, including organic (i.e. melanin, lignin) metal oxides (i.e. cerium oxide) or metal (i.e. gold, platinum) based nanoparticles, exhibit intrinsic redox activity that is often associated with radical trapping and/or with superoxide dismutase-like and catalase-like activities. Redox inactive nanomaterials can be transformed into antioxidants by grafting low molecular weight antioxidants on them. Herein, we propose a classification of nanoantioxidants based on their mechanism of action, and we review the chemical methods used to measure antioxidant activity by providing a rationale of the chemistry behind them.

Few-layered MoSe2 nanosheets as an efficient peroxidase nanozyme for highly sensitive colorimetric detection of H2O2 and xanthine

MoSe₂ nanosheets possess intrinsic peroxidase-like activity and are applied to H₂O₂ and xanthine detection with high sensitivity and selectivity.

Selenium-Functionalized Graphene Oxide That Can Modulate the Balance of Reactive Oxygen Species

Graphene oxide (GO) is an important two-dimensional material since it is water-soluble and can be functionalized to adapt to different applications. However, the current covalent functionalization methods usually require hash conditions, long duration, and sometimes even multiple steps, while noncovalent functionalization is inevitably unstable, especially under a physiological environment where competing species exist. Diselenide bond is a dynamic covalent bond and can respond to both redox conditions and visible light irradiation in a sensitive manner. Thus, in this work by combining the stimuli response of diselenide bond and the oxidative/radical attackable nature of GO, we achieved the in situ covalent functionalization of GO simply by stirring GO with diselenide-containing molecules in aqueous solution. The covalent functionalization was proved by Fourier transform infrared, time-of-flight secondary ion mass spectrometry, atomic force microscopy, thermogravimetric analysis, and so forth, and the functionalization mechanism was deduced to involve both redox reaction and radical addition reaction according to the X-ray photoelectron spectrscopy, atomic emission spectroscopy, and Raman spectroscopy. Moreover, we modified GO with a biocompatible diselenide-containing polymer (mPEGSe)₂ and found selenium-functionalized GO could modulate the balance of reactive oxygen species (ROS). GOSe could decrease ROS level by accelerating the reduction of peroxides when the ROS concentration is high while boosting the ROS level by in situ generating ROS when its concentration is relatively low.