Nanozymes With CAT-like Activity

Introduction

With the deepening of research on nanozymes with catalase (CAT)-like activity, more and more researchers have begun to pay attention to this field. CAT, as the important part of the enzymatic antioxidant system in the biosystem, can catalyze the decomposition of H₂O₂. Similar to CAT, nanozymes with CAT-like activity are capable of catalyzing the degradation of H₂O₂ to produce O₂ and H₂O. They have high catalytic activity and stability and can be used in cancer therapy, hepatic injury prevention, etc. With the continuous advancement of technology and in-depth research, it is believed that the application prospects of nanozymes with CAT-like activity will be broader.

Study On Catalytic Mechanism

Nanozymes with catalase (CAT)-like activity are gradually being intensively studied, especially the study of their catalytic mechanism has aroused widespread interest among scientists. For example, Celardo et al. put forward a possible catalytic model of CeO₂ nanoparticles (NPs) with CAT-like activity in 2011. As shown in Figure 1, H₂O₂ was firstly bind to the 2Ce⁴⁺ binding sites presented by the oxygen vacancy site of CeO₂ NPs. Then, the fully reduced oxygen vacancy site was formed as the protons released and two electrons transferred to the two Ce⁴⁺. The oxygen was generated from the reduced oxygen vacancy site. Afterwards, another H₂O₂ molecule was bind to the 2Ce³⁺ sites. The homolysis of O–O bond happened with the transfer of two electrons and a uptake of two protons. After H₂O molecules released, the initial Ce⁴⁺ sites were regenerated on CeO₂ NPs surface^[1]. Furthermore, Guo et al. investigated the possible catalytic mechanism of Co₃O₄ nanozyme with CAT-like activity at atomic or molecular level, involving the base-like dissociative, acid-like dissociative, and bi-hydrogen peroxide associative mechanisms. Based on the calculation of thermochemical energies and associated activation barriers, they confirmed that the bi-hydrogen peroxide associative mechanism was most viable for the CAT-mimicking catalytic recycle of Co₃O₄. The reaction mechanism is as follows. It started with two H₂O₂ molecules coadsorption at the (Co₃O₄)_n surface. One H₂O₂ molecule dissociated into two OH species and the other H₂O₂ molecule dissociated into HOO and H species, OH and H formed H₂O molecule. Subsequently, HOO could readily undergo dissociative chemisorption on the (Co₃O₄)_n surface, with H atom anchored to the surface oxygen. The O₂ molecule was then formed and desorbed from the HOO^[2].

Fig.1 Mechanism of CeO₂ NPs with CAT-like activity.

Applications

Based on the properties of nanozymes with CAT-like activity and their catalytic mechanisms, diverse applications of these products in cancer therapy, hepatic injury prevention, etc. have been achieved.

• Cancer therapy. Nanozymes with CAT-like activity have broad application prospects in the field of cancer therapy. They can be used for photodynamic therapy (PDT), chemodynamic therapy (CDT), photothermal therapy (PTT), radiation therapy, etc. of cancer, which have a good killing effect on tumors. For example, Ma et al. used Au NPs with high CAT-like activity modified nano metal-organic frameworks (Au@ZIF-8) for highly efficient photodynamic therapy^[3].

• Hepatic injury prevention. Nanozymes with CAT-like activity can be used to prevent liver damage induced by acetaminophen and 3-amino-1,2,4-triazole. They can directly scavenge reactive oxygen species (ROS) from liver injury sites and relieve oxidative stress. In addition, while clearing ROS, they can produce a large amount of O₂, significantly alleviate tissue hypoxia, thereby further alleviating liver damage. For example, in Singh's work, cerium oxide-based nanozymes (CeNPs) with CAT-like activity were shown to be useful in preventing hepatic injury in liver cells. CeNPs effectively scavenged the free radicals generated due to elevated H₂O₂ inside the cells. Therefore they can protect hepatic cells from cytotoxicity and genetic damage from the high concentrations of H₂O₂ in the absence of functional CAT^[4].

Alfa Chemistry offers a series of nanozymes with CAT-like activity, which can be used for cancer therapy and hepatic injury prevention. 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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