Circulating microRNAs (miRNAs) play a pivotal role in the occurrence and development of acute myocardial infarction (AMI), and precise detection of them holds significant clinical implications. The development of luminol-based luminophores in the field of electrochemiluminescence (ECL) for miRNA detection has been significant, while their effectiveness is hindered by the instability of co-reactant hydrogen peroxide (H₂O₂). In this work, an iron single-atom catalyst (Fe-PNC) was employed for catalyzing the luminol-O₂ ECL system to achieve ultra-sensitive detection of myocardial miRNA. Target miRNA triggers a hybridization chain reaction (HCR), resulting in the generation of a DNA product featuring multiple sticky ends that facilitate the attachment of Fe-PNC probes to the electrode surface. The Fe-PNC catalyst exhibits high promise and efficiency for the oxygen reduction reaction (ORR) in electrochemical energy conversion systems. The resulting ECL biosensor allowed ultrasensitive detection of myocardial miRNA with a low detection limit of 0.42 fM and a wide linear range from 1 fM to 1.0 nM. Additionally, it demonstrates exceptional performance when evaluated using serum samples collected from patients with AMI. This work expands the application of single-atom catalysis in ECL sensing and introduces novel perspectives for utilizing ECL in disease diagnosis.

Single atom catalysts (SACs) have attracted considerable attention due to their unique structures and excellent catalytic performance, especially in the area of catalysis science and energy conversion and storage. In recent years, SACs have emerged as a new type of sensing material for constructing electrochemical sensors (ECSs), presenting excellent sensitivity, selectivity, and stability. Herein, we review the recent advances of SACs in electrochemical sensing and discuss the status quo of current SAC-based ECSs. Specifically, the fundamentals of SAC-based ECSs are outlined, including the involved central metal atoms and various supports of SACs in this field, the detection mechanisms, and improving strategies of SAC-based ECSs. Moreover, the important applications of SAC-based ECSs are listed and classified, covering the detection of reactive oxygen and nitrogen species, environmental pollutants, disease biomarkers, and pharmaceuticals. Last, based on abundant reported cases, the current conundrums of SAC-based ECSs are summarized, and the prediction of their future developing trends is also put forward.

Single-atom nanozymes (SAZs) with peroxidase (POD)-like activity have good nanocatalytic tumor therapy (NCT) capabilities. However, insufficient hydrogen peroxide (H₂O₂) and hydrogen ions in the cells limit their therapeutic effects. Herein, to overcome these limitations, a biomimetic single-atom nanozyme system was developed for self-enhanced NCT. We used a previously described approach to produce platelet membrane vesicles. Using a high-temperature carbonization approach, copper SAZs with excellent POD-like activity were successfully synthesized. Finally, through physical extrusion, a proton pump inhibitor (PPI; pantoprazole sodium) and the SAZs were combined with platelet membrane vesicles to create PPS. Both in vivo and in vitro, PPS displayed good tumor-targeting and accumulation abilities. PPIs were able to simultaneously regulate the hydrogen ion, glutathione (GSH), and H₂O₂ content in tumor cells, significantly improve the catalytic ability of SAZs, and achieve self-enhanced NCT. Our in vivo studies showed that PPS had a tumor suppression rate of > 90%. PPS also limited the synthesis of GSH in cells at the source; thus, glutamine metabolism therapy and NCT were integrated into an innovative method, which provides a novel strategy for multimodal tumor therapy.

In recent years, the isolated single-atom site (ISAS) catalysts have attracted much attention as they are cost-effective, can achieve 100% atom-utilization efficiency, and often display superior catalytic performance. Here, we developed a biomass-assisted pyrolysis-etching-activation (PEA) strategy to construct ISAS metal decorated on N and B co-doped porous carbon (ISAS M/NBPC, M = Co, Fe, or Ni) catalysts. This PEA strategy can be applied in the universal and large-scale preparation of ISAS catalysts. Interestingly, the ISAS M/NBPC (M = Co, Fe, or Ni) catalysts show multi-functional features and excellent catalytic activities. They can be used to conduct different types of catalytic reactions, such as O-silylation (OSI), oxidative dehydrogenation (ODH), and transfer hydrogenation (THG). In addition, we used the transfer hydrogenation of nitrobenzene as a typical reaction and revealed the difference between ISAS Co/NBPC and ISAS Co/NPC (N-doped porous carbon) catalysts by density functional theory (DFT) calculations, and which showed that the decreased barrier of the rate-determining step and the low-lying potential energy diagram indicate that the catalytic activity is higher when ISAS Co/NBPC is used than that when ISAS Co/NPC is used. These results demonstrate that the catalytic performance can be effectively improved by adjusting the coordination environment around the ISAS.

In the field of electrolysis of water, the design and synthesis of catalysts over a wide pH range have attracted extensive attentions. In this paper, Co and N are co-introduced into the structural unit of tungsten disulfide (WS₂), and the hydrogen evolution reaction (HER) performances of different WS₂-based catalysts are theoretically predicted and systematically studied by density functional theory (DFT) calculations. With the guidance of DFT calculations, an evaporation-pyrolysis strategy is applied to prepare Co and N co-doped WS₂ (Co,N-WS₂) flower-like nanosheets, which exhibits excellent HER performance over a wide pH range. In addition, the DFT calculations show that the active sites in Co,N-WS₂ have a good ability of hydrogen adsorption after the introduction of Co and N, suggesting that such a co-doping system will be an ideal catalyst for oxidative dehydrogenation (ODH). The following experiment results indeed evidence that the Co,N-WS₂ catalyst displays a high activity in the ODH of 1,2,3,4-tetrahydroquinoline (4H-quinoline) and its derivatives. Therefore, this work provides a good example for the rational design and accurate preparation of functional catalysts, which enables it possible to develop other efficient catalysts with multiple functions.