When Nanozymes Meet Single‐Atom Catalysis

Abstract

Nanomaterials with enzyme‐like activities, coined nanozymes, have been researched widely as they offer unparalleled advantages in terms of low cost, superior activity, and high stability. The complex structure and composition of nanozymes has led to extensive investigation of their catalytic sites at an atomic scale, and to an in‐depth understanding of the biocatalysis occurring. Single‐atom catalysts (SACs), characterized by atomically dispersed active sites, have provided opportunities for mimicking metalloprotease and for bridging the gap between natural enzymes and nanozymes. In this Minireview, we illustrate the unique properties of nanozymes and we discuss recent advances in the synthesis, characterization, and applications of SACs. Subsequently, we outline the impressive progress made in single‐atom nanozymes and we discuss their applications in sensing, degradation of organic pollutants, and in therapeutic roles. Finally, we present the major challenges and opportunities remaining for a successful marriage of nanozymes and SACs.

Single‐Atom Catalysts in Catalytic Biomedicine

“…Recently, the scientific community has witnessed the significant breakthroughs of supported single-atom catalysts (SACs) for versatile biomedical applications due to their excellent catalytic performance, selectivity, and stability of atomically distributed metal atoms, which are attributed to several factors, covering maximum atomic utilization efficiency, unsaturated coordination environment, quantum size effect, and strengthened support-metal atoms interaction. [19] Herein, we summarize and discuss the very recent progress in the synthetic strategies, surface engineering, characterization techniques, and catalytic activities of SACs for versatile biomedical applications. Furthermore, we discuss some specific paradigms of biomedical use of SACs, focusing on biosensing, anticancer therapy, antibacterial treatment, and oxidative-stress cytoprotection (Table 1).…”

“…[32] In addition, similar to nanosized catalysts, these reported SACs may promote two or more kinds of catalytic reactions under endogenous/exogenous stimuli, which thus lower the catalytic activity and selectivity towards one specific biomedical reaction. [19] Therefore, in-depth comprehending the synthetic processes of SACs and exploiting feasible strategies (heteroatom doping, defects, multiple metal loading, and appropriate precursors) are vital to improve the active-site density of SACs and enhance the selectivity for specific catalytic reactions, thereby implementing high-performance catalytic reactions for desirable biomedical applications.…”

“…Currently, the majority of catalytic processes in biomedical applications are monitored via ex situ spectroscopic and microscopic approaches. [19] However, the actual active sites of catalytic processes in biomedical applications may be incongruity with that monitored by ex situ characterization strategies owing to some chemical or physical factors, such as pH, temperature, biological surroundings, and reaction substances. [53] Consequently, developing direct and efficient in situ dynamic measurements, such as in situ STM, XAFS, STEM, and FTIR, is of prominent significance to fundamentally understand the in vitro and in vivo catalytic processes and reaction mechanism as well as rational design of high-performance SACs for versatile biomedical applications.…”

“…They exhibit high potential in protecting cells from oxidative stress. [19] For instance, Fe single atoms dispersed on N-doped porous carbon (Fe-SAs/NC) was fabricated and utilized to mimic antioxidative enzymes for efficiently scavenging ROS. [46] The obtained Fe-SAs/NC accelerated the disassociation of H 2 O 2 into H 2 O and O 2 as well as O 2 • − into H 2 O 2 and O 2 , thus facilitating them to scavenge cellular ROS as produced in the process of oxidative stress (Figure 12a).…”

Dioxygen Binding to all 3d, 4d, and 5d Transition Metals from Coupled‐Cluster Theory

“…[59,60] Large-system DFT descriptors are not likely to be successful due to the uncertainties described above, including model-dependent errors and issues with chemical composition and sampling of conformations. [61,62] Instead, we have argued that small systems are required, [48,63] because 1) they are the minimal catalytic units relevant to single-atom catalysis; [9,[64][65][66][67][68] 2) their data are less noisy and errorprone in terms of solvent, conformation sampling, and chemical composition; 3) they can be studied by high-quality quantum chemistry; 4) they do not suffer the complex and partly inseparable modulations from large-scale catalyst structure, which can be added systematically to enable rational predictive power; [69] 5) their trend chemistry transfers to large systems because other modulating effects are secondary in magnitude to the local, very strong metal-oxygen interactions that have the similar d-block trends and physical effects in large and small systems. [55,69] The present paper reports coupled-cluster CCSD(T) energies of all the 3d-, 4d-, and 5d-transition MO 2 complexes, and reports the bond strengths of the MÀ O 2 and (M)C-> OÀ O bonds to assess trends in OÀ O bond activation.…”