Nanozymes With GPx-like Activity

Introduction

Nanozymes with glutathione peroxidase (GPx)-like activity can convert excess H₂O₂ into H₂O by catalyzing glutathione (GSH) and reduce its damage to organisms. Therefore, they have received widespread attention in antioxidation research and applications. In addition to their excellent reactive oxygen species (ROS) removal ability, the nanozymes with GPx-like activity also have good catalytic efficiency and stability. And they are also widely used in imaging.

Study On Catalytic Mechanism

With the in-depth study of nanozymes with GPx-like activity, the exploration of their catalytic mechanism has gradually become a research hotspot. GPx is a kind of antioxidant enzyme with selenium-cysteine as its catalytic center. Therefore, research on the catalytic mechanism of nanozymes with GPx-like activity mainly focuses on selenium-based nanozymes. In 2017, Qu, Ren, and co-workers rationally fabricated a novel nanozyme (GO-Se) with remarkable GPx-like activity by assembling graphene oxide (GO) and selenium. Similar to natural GPx, GO-Se nanozyme might follow a ping-pong reaction mechanism to catalyze the decomposition of H₂O₂. The catalytic mechanism is shown in Figure 1. One molecule H₂O₂ first reacted with nanoselenium to generate selenium oxide intermediate. The obtained intermediate then oxidized GSH to produce oxidized glutathione (GSSG) while the selenium intermediate would return to its initial state. With the assistance of glutathione reductase (GR) as well as its coenzyme nicotinamide adenine dinucleotide phosphate (NADPH), GSSG was reduced to GSH. Then the nanoselenium component could react with another H₂O₂ molecule^[1].

Fig.1 Catalytic mechanism of GO-Se nanozyme with GPx-like activity.

In addition, a series of studies have been conducted on the catalytic mechanism of vanadium-based nanozymes with GPx-like activity. In 2014, Mugesh, D'Silva, and co-workers proposed a catalytic mechanism of V₂O₅ nanowires with significant GPx-like antioxidant activity, as shown in Figure 2. First, the surface of V acts as a template for the reduction of H₂O₂ by GSH. Then GS^- could generate an unstable sulfenate-bound intermediate 2 through the nucleophilic attack of complex 1 on the peroxide bond. This intermediate could then hydrolyze to produce glutathione sulfenic acid 3 and dihydroxo intermediate 4. After that, intermediate 4 would react with H₂O₂ to regenerate complex 1^[2].

Fig.2 Catalytic mechanism of V₂O₅ nanowires with GPx-like activity.

Applications

Based on the GPx-like activity of nanozymes, several important applications have been exploited, such as antioxidation and imaging.

• Antioxidation. Nanozymes with GPx-like activity are important antioxidant enzymes. They have significant ROS scavenging ability and can protect cellular components from oxidative damage, and thus are widely used for cytoprotection. Their excellent antioxidant capacity can also effectively alleviate ear inflammation, enteritis, and pneumonia, indicating the potential of nanozymes with GPx-like activity for anti-inflammatory treatment.

• Imaging. As an excellent multifunctional imaging probe, nanozymes with GPx-like activity are widely used in imaging. They can be used for versatile imaging of base-excision repair (BER) in living cells, as well as magnetic resonance imaging (MRI), photoacoustic imaging, ultrasound imaging, etc. in the diagnosis and treatment of diseases.

Alfa Chemistry offers a series of nanozymes with GPx-like activity, which can be used for  antioxidation and imaging. You can click on our product list for a detailed view. At the same time, we also offer product customization according to customer's detailed requirements. If you are interested in our products or have any questions or needs, please feel free to contact us. We will be happy to provide you with support and services.

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