Which is Better for Nanomedicines: Nanocatalysts or Single-Atom Catalysts?

Global trends and emerging research in nanotechnology for esophageal cancer: a comprehensive bibliometric analysis

BACKGROUND

Despite the growing body of research on nanotechnology for esophageal cancer (EC), a comprehensive bibliometric analysis in this field has yet to be conducted. This study aims to fill this gap by analyzing global research trends, key contributors, and emerging themes in nanotechnology for EC.

METHODS

A bibliometric analysis was performed on publications from 1980 to 2024, using data from the Web of Science Core Collection. The analysis was conducted using VOSviewer, CiteSpace, and the R package 'bibliometrix' to visualize research trends, collaboration networks, and thematic areas.

RESULTS

The analysis included 419 documents authored by 2952 researchers from 44 countries. A significant increase in publications was observed, particularly after 2011, with China, the United States, and Japan leading the contributions. Prominent institutions, including Zhengzhou University and the Chinese Academy of Sciences, were identified as key players. The research predominantly focused on drug delivery systems, nanomedicine, and cancer treatment mechanisms, with emerging trends in the development of advanced nanomaterials for personalized therapies.

CONCLUSION

This comprehensive bibliometric analysis of nanotechnology applications in EC highlights global research trends, key contributors, and emerging research areas. The findings underscore the crucial role of nanotechnology in advancing treatment strategies for EC and identify areas for future research and interdisciplinary collaboration.

Effect of Metal Site Mobility of Single-Atom Catalyst on Photocatalytic Water Oxidation

Understanding the impact of catalytic site diffusion on photocatalytic performance is crucial to the rational design of water oxidation photocatalysts. In this study, we combined ab initio nonadiabatic molecular dynamics (NAMD) with density functional theory (DFT) calculations to investigate single-atom transition metals (Ni, Pd) loaded on HfS2 and their diffusion effects on photocatalytic water oxidation. Transition state calculations indicated that the barriers (0.58 eV) enable the diffusion possibility between the most stable HS site and the metastable HHf site for Pd/1T-HfS2. Moreover, electronic structure simulations reveal distinct properties of Pd/1T-HfS2:Pd adsorption at the HHf site generate a deep defect state (∼0.5 eV above the valence band maximum (VBM)), while adsorption at the HS site introduces a shallow defect state near the VBM (∼0.2 eV above the VBM). Compared to that of pristine 1T-HfS2 (6.2 ns), the electron-hole recombination time extends to 7 ns for Pd(HS)/1T-HfS2 but decreases to 1.7 ns for Pd(HHf)/1T-HfS2, driven by the position of the Pd-induced defect states. Thermodynamically, the catalytic properties of Pd(HS)/1T-HfS2 and Pd(HHf)/1T-HfS2 show a pronounced difference, approximately 0.08 V in limiting potential. Generally, this study enhances understanding of dynamic photocatalytic properties in single-atom catalysts.

Advancements on Single-Atom Catalysts-Mediated Persulfate Activation: Generating Reactive Species for Contaminants Elimination in Water

The single-atom catalyst (SAC) activated persulfate process has emerged as a highly efficient technology for eliminating refractory organic compounds in aqueous environments. This review delves into the intricacies of utilizing SACs for the effective removal of various contaminants in water. The common supports and the preparation procedures of SACs are summarized at first. The synthesis methods of SACs (i.e., wet chemical method, one-pot hydrothermal method, and high-temperature pyrolysis method) are also described. Then, a comprehensive overview of the diverse reaction mechanisms in SAC-activated persulfate systems is presented, including a radical oxidation process via sulfate or hydroxyl radicals and superoxide radicals, or a nonradical process via single oxygen, surface active complex, and high-valent metal-oxo species oxidation. The impact of key factors such as peroxides concentration, SAC dosage, reaction pH, inorganic anions, organic matter, operando stability, and real water is also delved. The removal of various pollutants (i.e., azo dyes, phenolic compounds, pharmaceuticals, and bacteria) by this process is further summarized. Finally, the challenges and perspectives in the field of water treatment utilizing SACs are discussed.

Safety Landscape of Therapeutic Nanozymes and Future Research Directions

Oxidative stress and inflammation are at the root of a multitude of diseases. Treatment of these conditions is often necessary but current standard therapies to fight excessive reactive oxygen species (ROS) and inflammation are often ineffective or complicated by substantial safety concerns. Nanozymes are emerging nanomaterials with intrinsic enzyme-like properties that hold great promise for effective cancer treatment, bacterial elimination, and anti-inflammatory/anti-oxidant therapy. While there is rapid progress in tailoring their catalytic activities as evidenced by the recent integration of single-atom catalysts (SACs) to create next-generation nanozymes with superior activity, selectivity, and stability, a better understanding and tuning of their safety profile is imperative for successful clinical translation. This review outlines the current applied safety assessment approaches and provides a comprehensive summary of the safety knowledge of therapeutic nanozymes. Overall, nanozymes so far show good in vitro and in vivo biocompatibility despite considerable differences in their composition and enzymatic activities. However, current safety investigations mostly cover a limited set of basic toxicological endpoints, which do not allow for a thorough and deep assessment. Ultimately, remaining research gaps that should be carefully addressed in future studies are highlighted, to optimize the safety profile of therapeutic nanozymes early in their pre-clinical development.

Atomically dispersed single-atom catalysts (SACs) and enzymes (SAzymes): synthesis and application in Alzheimer's disease detection

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline and memory loss. Conventional diagnostic methods, such as neuroimaging and cerebrospinal fluid analysis, typically detect AD at advanced stages, limiting the efficacy of therapeutic interventions. Early detection is crucial for improving patient condition by enabling timely administration of treatments that may decelerate disease progression. In this context, single-atom catalysts (SACs) and single-atom nanozymes (SAzymes) have emerged as promising tools offering highly sensitive and selective detection of Alzheimer's biomarkers. SACs, consisting of isolated metal atoms on a support surface, deliver unparalleled atomic efficiency, increased reactivity, and reduced operational costs, although certain challenges in terms of stability, aggregation, and other factors persist. The advent of SAzymes, which integrate SACs with natural metalloprotease catalysts, has further advanced this field by enabling controlled electronic exchange, synergistic productivity, and enhanced biosafety. Particularly, M-N-C SACs with M-Nx active sites mimic the selectivity and sensitivity of natural metalloenzymes, providing a robust platform for early detection of AD. This review encompasses the advancements in SACs and SAzymes, highlighting their pivotal role in bridging the gap between conventional enzymes and nanozyme and offering enhanced catalytic efficiency, controlled electron transfer, and improved biosafety for Alzheimer's detection.

Designing Efficient Single Metal Atom Biocatalysts at the Atomic Structure Level

Various nanomaterials as biocatalysts could be custom-designed and modified to precisely match the specific microenvironment of diseases, showing a promise in achieving effective therapy outcomes. Compared to conventional biocatalysts, single metal atom catalysts (SMACs) with maximized atom utilization through well-defined structures offer enhanced catalytic activity and selectivity. Currently, there is still a gap in a comprehensive overview of the connection between structures and biocatalytic mechanisms of SMACs. Therefore, it is crucial to deeply investigate the role of SMACs in biocatalysis from the atomic structure level and to elucidate their potential mechanisms in biocatalytic processes. In this minireview, we summarize catalysis regulation methods of SMACs at the atomic structure level, focusing on the optimization of catalytic active sites, coordination environment, and active site-support interactions, and briefly discuss biocatalytic mechanisms for biomedical applications.

In the View of Electrons Transfer and Energy Conversion: The Antimicrobial Activity and Cytotoxicity of Metal-Based Nanomaterials and Their Applications

The global pandemic and excessive use of antibiotics have raised concerns about environmental health, and efforts are being made to develop alternative bactericidal agents for disinfection. Metal-based nanomaterials and their derivatives have emerged as promising candidates for antibacterial agents due to their broad-spectrum antibacterial activity, environmental friendliness, and excellent biocompatibility. However, the reported antibacterial mechanisms of these materials are complex and lack a comprehensive understanding from a coherent perspective. To address this issue, a new perspective is proposed in this review to demonstrate the toxic mechanisms and antibacterial activities of metal-based nanomaterials in terms of energy conversion and electron transfer. First, the antimicrobial mechanisms of different metal-based nanomaterials are discussed, and advanced research progresses are summarized. Then, the biological intelligence applications of these materials, such as biomedical implants, stimuli-responsive electronic devices, and biological monitoring, are concluded based on trappable electrical signals from electron transfer. Finally, current improvement strategies, future challenges, and possible resolutions are outlined to provide new insights into understanding the antimicrobial behaviors of metal-based materials and offer valuable inspiration and instructional suggestions for building future intelligent environmental health.

Research Progress of Nanomedicine-Based Mild Photothermal Therapy in Tumor

With the booming development of nanomedicine, mild photothermal therapy (mPTT, 42-45°C) has exhibited promising potential in tumor therapy. Compared with traditional PTT (>50°C), mPTT has less side effects and better biological effects conducive to tumor treatment, such as loosening the dense structure in tumor tissues, enhancing blood perfusion, and improving the immunosuppressive microenvironment. However, such a relatively low temperature cannot allow mPTT to completely eradicate tumors, and therefore, substantial efforts have been conducted to optimize the application of mPTT in tumor therapy. This review extensively summarizes the latest advances of mPTT, including two sections: (1) taking mPTT as a leading role to maximize its effect by blocking the cell defense mechanisms, and (2) regarding mPTT as a supporting role to assist other therapies to achieve synergistic antitumor curative effect. Meanwhile, the special characteristics and imaging capabilities of nanoplatforms applied in various therapies are discussed. At last, this paper puts forward the bottlenecks and challenges in the current research path of mPTT, and possible solutions and research directions in future are proposed correspondingly.

A Platelet-Mimicking Single-Atom Nanozyme for Mitochondrial Damage-Mediated Mild-Temperature Photothermal Therapy

Single-atom nanozyme (SAzyme) systems have shown great potential in tumor therapy. A multifunctional SAzyme not only possesses high catalytic activity but also can be used as photothermal agents in photothermal therapy (PTT). Furthermore, it is also imperative to overcome tumor thermal resistance in SAzyme-based PTT so that PTT under a mild temperature is achievable. Herein, a novel platelet membrane (PM)-coated mesoporous Fe single-atom nanozyme (Fe-SAzyme) was formulated to solve these issues. The PM-coated mesoporous Fe-SAzyme (PMS) showed a satisfactory NIR-II photothermal performance, high peroxidase (POD) activity, and good tumor-targeting ability. In addition, PMS may be used as a carrier for protein drugs owing to its inner mesoporous structure. In vitro experiments showed that PMS could inhibit the expression of heat shock protein (HSP) by damaging the mitochondria, thereby finally improving the effect of mild-temperature PTT. Moreover, in vivo results showed that PMS could efficiently accumulate in tumor sites and suppress tumor growth with minimal toxicity in major organs. To the best of our knowledge, this study is the first report of a biomimetic mesoporous Fe-SAzyme used to achieve mitochondrial damage-mediated mild-temperature PTT. The study provides new promising ideas for designing other SAzyme systems for cancer treatment.

Emerging Single-Atom Catalysts/Nanozymes for Catalytic Biomedical Applications

Single-atom catalysts (SACs) are a type of atomically dispersed nanozymes with the highest atom utilization, which employ low-coordinated single atoms as the catalytically active sites. SACs not only inherit the merits of traditional nanozymes, but also hold high catalytic activity and superb catalytic selectivity, which ensure their tremendous application potential in environmental remediation, energy storage and conversion, chemical industry, nanomedicine, etc. Nevertheless, undesired aggregation effect of single atoms during preactivation and reaction processes is significantly enhanced owing to the high surface free energy of single atoms. In this case, appropriate substrates are requisite to prevent the aggregation event through the powerful interactions between the single atoms and the substrates, thereby stabilizing the high catalytic activity of the catalysts. In this review, the synthetic methods and characterization approaches of SACs are first described. Then the application cases of SACs in nanomedicine are summarized. Finally, the current challenges and future opportunities of the SACs in nanomedicine are outlined. It is hoped that this review may have implications for furthering the development of new SACs with improved biophysicochemical properties and broadened biomedical applications.

Copper single-atom catalysts with photothermal performance and enhanced nanozyme activity for bacteria-infected wound therapy

Nanozymes have become a new generation of antibiotics with exciting broad-spectrum antibacterial properties and negligible biological toxicity. However, their inherent low catalytic activity limits their antibacterial properties. Herein, Cu single-atom sites/N doped porous carbon (Cu SASs/NPC) is successfully constructed for photothermal-catalytic antibacterial treatment by a pyrolysis-etching-adsorption-pyrolysis (PEAP) strategy. Cu SASs/NPC have stronger peroxidase-like catalytic activity, glutathione (GSH)-depleting function, and photothermal property compared with non-Cu-doped NPC, indicating that Cu doping significantly improves the catalytic performance of nanozymes. Cu SASs/NPC can effectively induce peroxidase-like activity in the presence of H2O2, thereby generating a large amount of hydroxyl radicals (•OH), which have a certain killing effect on bacteria and make bacteria more susceptible to temperature. The introduction of near-infrared (NIR) light can generate hyperthermia to fight bacteria, and enhance the peroxidase-like catalytic activity, thereby generating additional •OH to destroy bacteria. Interestingly, Cu SASs/NPC can act as GSH peroxidase (GSH-Px)-like nanozymes, which can deplete GSH in bacteria, thereby significantly improving the sterilization effect. PTT-catalytic synergistic antibacterial strategy produces almost 100% antibacterial efficiency against Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA). In vivo experiments show a better PTT-catalytic synergistic therapeutic performance on MRSA-infected mouse wounds. Overall, our work highlights the wide antibacterial and anti-infective bio-applications of Cu single-atom-containing catalysts.