Deciphering the catalytic mechanism of superoxide dismutase activity of carbon dot nanozyme

Abstract

Nanozymes with superoxide dismutase (SOD)-like activity have attracted increasing interest due to their ability to scavenge superoxide anion, the origin of most reactive oxygen species in vivo. However, SOD nanozymes reported thus far have yet to approach the activity of natural enzymes. Here, we report a carbon dot (C-dot) SOD nanozyme with a catalytic activity of over 10,000 U/mg, comparable to that of natural enzymes. Through selected chemical modifications and theoretical calculations, we show that the SOD-like activity of C-dots relies on the hydroxyl and carboxyl groups for binding superoxide anions and the carbonyl groups conjugated with the π-system for electron transfer. Moreover, C-dot SOD nanozymes exhibit intrinsic targeting ability to oxidation-damaged cells and effectively protect neuron cells in the ischemic stroke male mice model. Together, our study sheds light on the structure-activity relationship of C-dot SOD nanozymes, and demonstrates their potential for treating of oxidation stress related diseases.

Red Emissive Carbon Dot Superoxide Dismutase Nanozyme for Bioimaging and Ameliorating Acute Lung Injury

“…[ 40 ] They concluded that the carboxyl groups on the surface of GQDs were the substrate‐binding sites, the carbonyl groups were the catalytically active sites, and the hydroxyl groups inhibited the catalytic activity. In our latest work, [ 42 ] we reported a C‐dot nanozyme with ultra‐high SOD‐like activity (>10000 U mg −1 ). The catalytic mechanism was revealed by surface modifications and theoretical calculations: The carboxyl and hydroxyl groups on the surface of C‐dots capture superoxide anions through hydrogen bonds, while the carbonyl groups coupling with the π‐system take part in electron transfer processes during disproportionation of superoxide anions.…”

“…[ 47 ] Here, by utilizing functional group protection strategies, we reveal that all of the carboxyl, hydroxyl and amino groups on the surface of C‐dots are closely related to the SOD enzymatic activity, which was consistent with our latest work. [ 42 ] Considering the N‐doped graphitic crystal structure and conjugated framework of C‐dots, we proposed a possible catalytic mechanism. The superoxide is anchored to the surface of the C‐dots through the hydrogen bond with the carboxyl group, hydroxyl, and amine groups.…”

Perspectives on Usage of Functional Nanomaterials in Antimicrobial Therapy for Antibiotic-Resistant Bacterial Infections

“…Carbon-based nanomaterials have gained popularity in biomedicine because of their desirable physical and chemical characteristics, biocompatibility, and ability to mimic various enzymes. Such materials have great mechanical qualities and can be used as wound dressings; examples are fullerene, graphene and its derivatives, carbon nitride, carbon dots (CDs), and carbon nanotubes (CNTs) . The peroxidase-like activity of a series of oxidized carbon nanotubes (o-CNTs) produced by Wang et al was exceptional throughout a broad pH range.…”

“…Such materials have great mechanical qualities and can be used as wound dressings; examples are fullerene, graphene and its derivatives, carbon nitride, carbon dots (CDs), and carbon nanotubes (CNTs). 64 The peroxidase-like activity of a series of oxidized carbon nanotubes (o-CNTs) produced by Wang et al 65 was exceptional throughout a broad pH range. The carbonyl-group on the oxidized carbon nanotube surface served as an active catalytic core, with the hydroxyl and carboxyl groups serving as competing sites.…”

Single-Atom Fe Nanozyme with Enhanced Oxidase-like Activity for the Colorimetric Detection of Ascorbic Acid and Glutathione

“…Over the past two decades, nanomaterials with enzyme-like characteristics, termed nanozyme, have attracted great attention because of their easy preparation, good stability in harsh conditions, and low cost. Up to now, a variety of nanomaterials have been discovered with enzyme-mimicking activity, such as transition metal oxide-based nanomaterials [ 14 , 15 , 16 , 17 ], noble metal- or metal-based nanostructures [ 18 , 19 , 20 ], carbon-based nanomaterials [ 21 , 22 , 23 ], and metal–organic framework-based nanostructures (MOFs) [ 24 , 25 , 26 ]. Although some progress has been made in this field, conventional nanozymes still face great challenges such as insufficient enzyme-like activity and low selectivity compared with natural enzymes.…”