Cu,Zn Dopants Boost Electron Transfer of Carbon Dots for Antioxidation

Rare-earth-free up and down-conversion dual-emission carbon dots for Cu2+ sensing

In this work, up- and down-conversion dual-emission CDs without rare-earth (UD D-CDs) were synthesized using RhB and 1,4-Diaminoanthraquinone as precursors. The synthesized UD D-CDs exhibited dual emissions at 496 and 580 nm under 260 and 865 nm excitation, respectively. The fluorescence emission mechanism, including contributions from carbon nuclei, surface states, molecular states, and internal defect states, was discussed through the separation and purification of UD D-CDs. Based on the interaction between UD D-CDs and copper ions (Cu2+), a dual-mode ratio fluorescence probe was developed to detect and quantify Cu2+. The up-conversion ratio fluorescent probe shows a linear range of 0.0500-15.0 μM, with a detection limit as low as 2.76 nM. This method has been successfully applied to detecting Cu2+ in human serum and has potential applications in biochemical analysis and biological imaging. The successful preparation of up-conversion fluorescent carbon dots without rare earth elements and the ability to perform low-damage detection in high-background biological samples provide a new approach to constructing non-rare earth up-conversion probes.

Unusual Antibacterial Property and Selectivity Enabled by Tuning Nanozyme Activities of L-Arginine Derived Carbon Dots

Functional integration of antimicrobial activity and cell proliferation promotion at low concentrations is important for the clinical application of carbon dots (CDs). In this study, the precursor, L-arginine, and dopant, copper salt, are used to prepare copper-doped CDs (Cu-CDs). Owing to their excellent synergistic enzyme-like activities, Cu-CDs can rapidly increase reactive oxygen species (ROS) to lethal levels, preferentially in bacteria, and exhibit potent antibacterial ability, which can mainly be attributed to the membrane disruption effect. Concurrently, the cell proliferation-promoting activity of arginine-derived CDs is inherited. The Cu-CDs achieve perfect integration of dual functions at low concentrations, especially advantageous for applications. With as little as 100 µg mL-1 of Cu-CDs, the infected wound heals obviously faster than 2 mg mL-1 of antibiotic, although the traditional antibiotic group shows slightly better antibacterial efficiency, suggesting its effect in simultaneously scavenging bacteria and promoting tissue repair effect in vivo. The super selective mechanism probably originates from the endocytosis of Cu-CDs by mammalian cells, while superoxide dismutase down-regulates ROS levels in cells to act as a mitotic signaling agent for promoting cell growth. This strategy provides an efficient, convenient, and safe solution to combat bacterial infections, and suggests a novel approach for modifying antimicrobial biomaterials.

Carbon Dots in the Pathological Microenvironment: ROS Producers or Scavengers?

Reactive oxygen species (ROS), as metabolic byproducts, play pivotal role in physiological and pathological processes. Recently, studies on the regulation of ROS levels for disease treatments have attracted extensive attention, mainly involving the ROS-induced toxicity therapy mediated by ROS producers and antioxidant therapy by ROS scavengers. Nanotechnology advancements have led to the development of numerous nanomaterials with ROS-modulating capabilities, among which carbon dots (CDs) standing out as noteworthy ROS-modulating nanomedicines own their distinctive physicochemical properties, high stability, and excellent biocompatibility. Despite progress in treating ROS-related diseases based on CDs, critical issues such as rational design principles for their regulation remain underexplored. The primary cause of these issues may stem from the intricate amalgamation of core structure, defects, and surface states, inherent to CDs, which poses challenges in establishing a consistent generalization. This review succinctly summarizes the recently progress of ROS-modulated approaches using CDs in disease treatment. Specifically, it investigates established therapeutic strategies based on CDs-regulated ROS, emphasizing the interplay between intrinsic structure and ROS generation or scavenging ability. The conclusion raises several unresolved key scientific issues and prominent technological bottlenecks, and explores future perspectives for the comprehensive development of CDs-based ROS-modulating therapy.

Tumour microenvironment-responded Fe-doped carbon dots-sensitized cubic Cu2O for Z-scheme heterojunction-enhanced sono-chemodynamic synergistic tumor therapy

The efficacy of electron-hole separation in a single sonosensitizer and the complexities of the tumor microenvironment (TME) present significant challenges to the effectiveness of sonodynamic therapy (SDT). Designing efficient sonosensitizers to enhance electron-hole separation and alleviate TME resistance is crucial yet challenging. Herein, we introduce a novel Z-scheme heterojunctions (HJs) sonosensitizer using Fe-doped carbon dots (CDs) as auxiliary semiconductors to sensitize cubic Cu2O (Fe-CDs@Cu2O) for the first time. Fe-CDs@Cu2O demonstrated enhanced SDT effects due to improved electron-hole separation. Additionally, the introduction of Fe ions in CDs synergistically enhances Fenton-like reactions with Cu ions in Cu2O, resulting in enhanced chemodynamic therapy (CDT) effects. Moreover, Fe-CDs@Cu2O exhibited rapid glutathione (GSH) depletion, effectively mitigating TME resistance. With high rates of 1O2 and OH generated by Fe-CDs@Cu2O, coupled with strong GSH depletion, single drug injection and ultrasound (US) irradiation effectively eliminate tumors. This innovative heterojunction sonosensitizer offers a promising pathway for clinical anti-tumor treatment.

Cu,Zn,I-Doped Carbon Dots with Boosted Triple Antioxidant Nanozyme Activity for Treatment of DSS-Induced Colitis

Nanozyme-mediated antioxidative therapy is a promising star for treating a myriad of important diseases through eliminating excessive reactive oxygen species (ROS) such as O2·- and H2O2, a critical mechanism for inflammatory bowel disease (IBD). This work provides a high biocompatibility iodine-copper-zinc covalent doped carbon dots (Cu,Zn,I-CDs) with the catalase (CAT)-, superoxide dismutase (SOD)- and glutathione peroxidase (GPx)-like catalytic activities for treating ulcerative colitis (UC) by scavenging overproduced ROS. We found that I dopant aids in counteracting the positive charge at Cu,Zn dopants brought on by low pH, enabling Cu,Zn,I-CDs to process strong triple antioxidant nanozyme activities rather than Cu,Zn-CDs. Vitro experiments displayed that the Cu,Zn,I-CDs could scavenge the excessive ROS to protect cellular against oxidative stress and reduce the expression of proinflammatory cytokines, such as TNF-α, IL-1β, and IL-6. In sodium dextran sulfate (DSS)-induced colitis mice models, Cu,Zn,I-CDs with excellent biocompatibility could effectively relieve the inflammation of the colon, containing the reduction of the colon length, the damaged epithelium, the infiltration of inflammatory cells, and upregulation of antioxidant genes. Therefore, the therapy of Cu,Zn,I-CD antioxidant nanozymes is an effective approach and provides a novel strategy for UC treatment.

Classification and application of metal-based nanoantioxidants in medicine and healthcare

Antioxidants play an important role in the prevention of oxidative stress and have been widely used in medicine and healthcare. However, natural antioxidants have several limitations such as low stability, difficult long-term storage, and high cost of large-scale production. Along with significant advances in nanotechnology, nanomaterials have emerged as a promising solution to improve the limitations of natural antioxidants because of their high stability, easy storage, time effectiveness, and low cost. Among various types of nanomaterials exhibiting antioxidant activity, metal-based nanoantioxidants show excellent reactivity because of the presence of an unpaired electron in their atomic structure. In this review, we summarize some novel metal-based nanoantioxidants and classify them into two main categories, namely chain-breaking and preventive antioxidant nanomaterials. In addition, the applications of antioxidant nanomaterials in medicine and healthcare are also discussed. This review provides a deeper understanding of the mechanisms of metal-based nanoantioxidants and a guideline for using these nanomaterials in medicine and healthcare.

Integrative analysis of bioinformatics and machine learning to identify cuprotosis-related biomarkers and immunological characteristics in heart failure

Backgrounds

Cuprotosis is a newly discovered programmed cell death by modulating tricarboxylic acid cycle. Emerging evidence showed that cuprotosis-related genes (CRGs) are implicated in the occurrence and progression of multiple diseases. However, the mechanism of cuprotosis in heart failure (HF) has not been investigated yet.

Methods

The HF microarray datasets GSE16499, GSE26887, GSE42955, GSE57338, GSE76701, and GSE79962 were downloaded from the Gene Expression Omnibus (GEO) database to identify differentially expressed CRGs between HF patients and nonfailing donors (NFDs). Four machine learning models were used to identify key CRGs features for HF diagnosis. The expression profiles of key CRGs were further validated in a merged GEO external validation dataset and human samples through quantitative reverse-transcription polymerase chain reaction (qRT-PCR). In addition, Gene Ontology (GO) function enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and immune infiltration analysis were used to investigate potential biological functions of key CRGs.

Results

We discovered nine differentially expressed CRGs in heart tissues from HF patients and NFDs. With the aid of four machine learning algorithms, we identified three indicators of cuprotosis (DLAT, SLC31A1, and DLST) in HF, which showed good diagnostic properties. In addition, their differential expression between HF patients and NFDs was confirmed through qRT-PCR. Moreover, the results of enrichment analyses and immune infiltration exhibited that these diagnostic markers of CRGs were strongly correlated to energy metabolism and immune activity.

Conclusions

Our study discovered that cuprotosis was strongly related to the pathogenesis of HF, probably by regulating energy metabolism-associated and immune-associated signaling pathways.

The Guidelines for the Design and Synthesis of Transition Metal Atom Doped Carbon Dots

Atoms doping is a practical approach to modulate the physicochemical properties of carbon dots (CDs) and thus has garnered increasing attention in recent years. Compared to non-metal atoms, transition metal atoms (TMAs) possess more unoccupied orbitals and larger atomic radii. TMAs doping can significantly alter the electronic structure of CDs and bestow them with new intrinsic characteristics. TMAs-doped CDs have exhibited widespread application potential as a new class of single-atom-based nanomaterials. However, challenges remain for the successful preparation and precise design of TMAs-doped CDs. The key to successfully preparing TMA-doped CDs lies in anchoring TMAs to the carbon precursors before the reaction. Herein, taking the formation mechanism of TMAs-doped CDs as a starting point, we systematically summarized the ligands employed for synthesizing TMAs-doped CDs and proposed the synthetic strategy involving multiple ligands. Additionally, we summarize the functional properties imparted to CDs by different TMA dopants to guide the design of TMA-doped CDs with different functional characteristics. Finally, we describe the bottlenecks TMAs-doped CDs face and provide an outlook on their future development.

Carbon dots with selective fluorescence response to hydroxyl radical for sensitive detection of bleomycin

In this work, antioxidant carbon dots (ACDs) with high quantum yield (63.98%) were developed through a one-step strategy using citric acid, ethylenediamine, and L-arginine as sources. The ACDs demonstrated excellent in vitro antioxidant activity. Additionally, ACDs displayed a unique fluorescence response to hydroxyl radical (OH). Leveraging this distinctive feature, a selective and sensitive fluorescence-based sensor was developed for detecting bleomycin (BLM) in the presence of ferrous ions (Fe2+). The studies on the oxidizing properties and dynamic quenching mechanism of ACDs by OH suggested that OH reduced the contents of the amino and hydroxyl groups of ACDs, leading to a decreased electron cloud density of ACDs for dynamic quenching of ACDs. Under optimally refined conditions, the detection limit of this strategy for BLM was 0.58 μg/mL, with a linear range spanning from 1 to 24 μg/mL when employing ACDs as the probe. This fluorescence sensing strategy provides a promising method for the detection of BLM in clinical samples.

Metal Site and Size-Controlled BTC-Based MOF as Cysteine Oxidase Mimic for Self-Cascade Detection of Cysteine and Hg2

Nanozyme-mediated strategy for sensing has been widely applied nowadays, in which the construction of a nanozyme cascade platform is an effective and challenging method to simulate the complexity and multifunctionality of natural systems. Herein, a simple and convenient self-cascade sensing platform was developed for the fluorescent detection of cysteine and Hg2+ by a BTC-based MOF through screening the metal sites and crystal sizes. By the introduction of polyvinylpyrrolidone, the as-prepared Cu-BTC possessed a metal center of Cu2+ and smaller size, which exhibited both cysteine oxidase- and peroxidase-like activities. The dual enzymic characters of Cu-BTC made a self-cascade reaction occur during which cysteine was first oxidized to cystine and generated H2O2 in the presence of O2, then H2O2 was decomposed into ·OH, and finally the ·OH triggered the turn-on fluorescence of Cu-BTC. Based on the self-cascade reactions and high affinity of Hg2+ and -SH within cysteine, a fluorescent method was developed to detect cysteine and Hg2+ with a range of 0-160/0-15 μM and a limit of detection of 0.04/0.09 μM, respectively. This work reveals the important role of the Cu2+ center for mimicking cysteine oxidase and gives a feasible strategy for constructing simple self-cascade reactions.

Reactive oxygen nanobiocatalysts: activity-mechanism disclosures, catalytic center evolutions, and changing states

Benefiting from low costs, structural diversities, tunable catalytic activities, feasible modifications, and high stability compared to the natural enzymes, reactive oxygen nanobiocatalysts (RONBCs) have become dominant materials in catalyzing and mediating reactive oxygen species (ROS) for diverse biomedical and biological applications. Decoding the catalytic mechanism and structure-reactivity relationship of RONBCs is critical to guide their future developments. Here, this timely review comprehensively summarizes the recent breakthroughs and future trends in creating and decoding RONBCs. First, the fundamental classification, activity, detection method, and reaction mechanism for biocatalytic ROS generation and elimination have been systematically disclosed. Then, the merits, modulation strategies, structure evolutions, and state-of-art characterisation techniques for designing RONBCs have been briefly outlined. Thereafter, we thoroughly discuss different RONBCs based on the reported major material species, including metal compounds, carbon nanostructures, and organic networks. In particular, we offer particular insights into the coordination microenvironments, bond interactions, reaction pathways, and performance comparisons to disclose the structure-reactivity relationships and mechanisms. In the end, the future challenge and perspectives for RONBCs are also carefully summarised. We envision that this review will provide a comprehensive understanding and guidance for designing ROS-catalytic materials and stimulate the wide utilisation of RONBCs in diverse biomedical and biological applications.

N-Acetyl-l-cysteine-Derived Carbonized Polymer Dots with ROS Scavenging via Keap1-Nrf2 Pathway Regulate Alveolar Bone Homeostasis in Periodontitis

Periodontitis is a type of chronic inflammatory oral disease characterized by the destruction of periodontal connective tissue and progressive alveolar bone resorption. As oxidative stress is the key cause of periodontitis in the early periodontal microenvironment, antioxidative therapy has been considered a viable treatment for periodontitis. However, more stable and effective reactive oxygen species (ROS)-scavenging nanomedicines are still highly needed due to the instability of traditional antioxidants. Herein, a new type of N-acetyl-l-cysteine (NAC)-derived red fluorescent carbonized polymer dots (CPDs) has been synthesized with excellent biocompatibility, which can serve as an extracellular antioxidant to scavenge ROS effectively. Moreover, NAC-CPDs can promote osteogenic differentiation in human periodontal ligament cells (hPDLCs) under H2 O2 stimulation. In addition, NAC-CPDs are capable of targeted accumulation in alveolar bone in vivo, reducing the level of alveolar bone resorption in periodontitis mice, as well as performing fluorescence imaging in vitro and in vivo. In terms of mechanism, NAC-CPDs may regulate redox homeostasis and promote bone formation in the periodontitis microenvironment by modulating the kelch-like ECH-associated protein l (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. This study provides a new strategy for the application of CPDs theranostic nanoplatform for periodontitis.

Modulating Electronic Structures of Iron Clusters through Orbital Rehybridization by Adjacent Single Copper Sites for Efficient Oxygen Reduction

The atom-cluster interaction has recently been exploited as an effective way to increase the performance of metal-nitrogen-carbon catalysts for oxygen reduction reaction (ORR). However, the rational design of such catalysts and understanding their structure-property correlations remain a great challenge. Herein, we demonstrate that the introduction of adjacent metal (M)-N4 single atoms (SAs) could significantly improve the ORR performance of a well-screened Fe atomic cluster (AC) catalyst by combining density functional theory (DFT) calculations and experimental analysis. The DFT studies suggest that the Cu-N4 SAs act as a modulator to assist the O2 adsorption and cleavage of O-O bond on the Fe AC active center, as well as optimize the release of OH* intermediates to accelerate the whole ORR kinetic. The depositing of Fe AC with Cu-N4 SAs on nitrogen doped mesoporous carbon nanosheet are then constructed through a universal interfacial monomicelles assembly strategy. Consistent with theoretical predictions, the resultant catalyst exhibits an outstanding ORR performance with a half-wave potential of 0.92 eV in alkali and 0.80 eV in acid, as well as a high power density of 214.8 mW cm-2 in zinc air battery. This work provides a novel strategy for precisely tuning the atomically dispersed poly-metallic centers for electrocatalysis.

Nanomedicine-Based Therapeutics for Myocardial Ischemic/Reperfusion Injury

Myocardial ischemic/reperfusion (IR) injury is a global cardiovascular disease with high mortality and morbidity. Therapeutic interventions for myocardial ischemia involve restoring the occluded coronary artery. However, reactive oxygen species (ROS) inevitably impair the cardiomyocytes during the ischemic and reperfusion phases. Antioxidant therapy holds great promise against myocardial IR injury. The current therapeutic methodologies for ROS scavenging depend predominantly on administering antioxidants. Nevertheless, the intrinsic drawbacks of antioxidants limit their further clinical transformation. The use of nanoplatforms with versatile characteristics greatly benefits drug delivery in myocardial ischemic therapy. Nanoplatform-mediated drug delivery significantly improves drug bioavailability, increases therapeutic index, and reduces systemic toxicity. Nanoplatforms can be specifically and reasonably designed to enhance molecule accumulation at the myocardial site. The present review initially summarizes the mechanism of ROS generation during the process of myocardial ischemia. The understanding of this phenomenon will facilitate the advancement of innovative therapeutic strategies against myocardial IR injury. The latest developments in nanomedicine for treating myocardial ischemic injury are then discussed. Finally, the current challenges and perspectives in antioxidant therapy for myocardial IR injury are addressed.

Ultrasonic enhancement of microdroplet-based interfacial reaction for improving the synthesis of Ag2S QDs

Ag2S quantum dots (QDs) have aroused extensive concerns in intravital imaging field due to their merits of narrow bandgap, low biological toxicity and decent fluorescence emission properties in the second near-infrared (NIR-II) window. However, low quantum yield (QY) and poor uniformity of Ag2S QDs are still main obstacles for its application. In this work, a novel strategy of utilizing ultrasonic field is presented, which can enhance the microdroplet-based interfacial synthesis of Ag2S QDs. The ultrasound increases the presence of ions at the reaction sites by enhancing the ion mobility in the microchennels. Therefore, the QY is enhanced from 2.33 % (optimal QY without ultrasound) to 8.46 %, which is the highest value of Ag2S ever reported without ion-doping. Also, the decrease of the corresponding full width at half maximum (FWHM) from 312 nm to 144 nm indicates the obvious uniformity improvement of the obtained QDs. Further mechanism exploration illustrates that ultrasonic cavitation significantly increases the interfacial reaction sites by splitting the droplets. Meanwhile, the acoustic flow field strengthens the ion renewal at the droplet interface. Consequently, the mass transfer coefficient increases by more than 500 %, which is favorable to improve both the QY and quality of Ag2S QDs. This work serves both fundamental research and practical production for the synthesis of Ag2S QDs.

Positively Charged Carbon Dots with Antibacterial and Antioxidant Dual Activities for Promoting Infected Wound Healing

Bacterial infection and excess reactive oxygen species are key factors that lead to slow or substantially delayed wound healing. It is crucial to design and develop new nanomaterials with antibacterial and antioxidative capabilities for wound healing. Here, positively charged carbon dots (CDs) are rationally designed and synthesized from p-phenylenediamine and polyethyleneimine by a facile one-pot solvothermal method, which show good biocompatibility in in vitro cytotoxicity, hemolysis assays, and in vivo toxicity evaluation. The positively charged CDs show superior antimicrobial effect against Staphylococcus aureus (S. aureus) at very low concentrations, reducing the risk of wound infection. At the same time, CDs with surface defects and unpaired electrons can effectively scavenge excess free radicals to reduce oxidative stress damage, accelerate wound inflammation-proliferation transition, and promote wound healing. The mouse model of skin infection demonstrates that CDs can effectively promote the wound healing of skin infection without obvious side effects by simply dropping or spraying onto the wound. We believe that the prepared CDs have satisfactory biocompatibility, antioxidant capacity, and excellent antibacterial activity and have great application potential in wound healing.

Unraveling the Structure Transition and Peroxidase Mimic Activity of Copper Sites over Atomically Dispersed Copper-Doped Carbonized Polymer Dots

The lack of systematic structural resolution makes it difficult to build specific transition-metal-atom-doped carbonized polymer dots (TMA-doped CPDs). Herein, the structure-activity relationship between Cu atoms and CPDs was evaluated by studying the peroxidase-like properties of Glu-Cu-CPDs prepared by using copper glutamate (Glu) with a Cu-N₂ O₂ initial structure. The results showed that the Cu atoms bound to Glu-Cu-CPDs in the form of Cu-N₂ C₂ , indicating that Cu-O bonds changed into Cu-C bonds under hydrothermal conditions. This phenomenon was also observed in other copper-doped CPDs. Moreover, the carboxyl and amino groups content decreased after copper-atom doping. Theoretical calculations revealed a dual-site catalytic mechanism for catalyzing H₂ O₂ . The detection of intracellular H₂ O₂ suggested their application prospects. Our study provides an in-depth understanding of the formation and catalytic mechanism of TMA-doped-CPDs, allowing for the generation specific TMA-doped-CPDs.

Multienzyme-Mimicking Au@Cu2O with Complete Antioxidant Capacity for Reactive Oxygen Species Scavenging

Most enzyme catalysts are unable to achieve effective oxidation resistance because of the monotonous mimicking function or production of secondary reactive oxygen species (ROS). Herein, the Au@Cu₂O heterostructure with multienzyme-like activities is deigned, which has significantly improved antioxidant capacity compared with pure Cu₂O for the scavenging of highly cell-damaging secondary ROS, i.e.,·OH. Experiments and theoretical calculations show that the heterostructure exhibits a built-in electric field and lattice mismatch at the metal-semiconductor interface, which facilitate to generate abundant oxygen vacancies, redox couples, and surface electron deficiency. On the one hand, the presence of rich oxygen vacancies and redox couple can enhance the adsorption and activation of oxygen-containing ROS (including O₂^·- and H₂O₂). On the other hand, the electron transfer between the electron-deficient Au@Cu₂O surface and electron donor would promote peroxide-like activity and avoid producing ·OH. Importantly, endogenous ·OH could be eliminated in both acidic and neutral conditions, which is no longer limited by the volatile physiological environment. Therefore, Au@Cu₂O can simulate superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and glutathione peroxidase (GPx) to form a complete antioxidant system. The deigned nanoenzyme is explored in the real sample world such as A549 cells and zebrafish. This work provides theoretical and practical strategies for the construction of a complete antioxidant enzyme system.

Construction of photo-induced zinc-doped carbon dots based on drug-resistant bactericides and their application for local treatment

In this project, we propose a highly effective photosensitizer that breaks through drug-resistant bacterial infections with zinc-doped carbon dots. By passing through the membrane of drug-resistant bacteria, the photosensitizers produce ROS in bacteria under the action of blue light to directly kill bacteria, so as to realize the antibacterial local treatment of drug-resistant bacteria. The experiment firstly uses an efficient one-step hydrothermal method to prepare zinc-doped red-light CDs as photosensitizers, in which zinc metal was doped to improve the optical properties of the CDs. Then we try first to use EDTA as a second-step attenuator for preparing CDs to obtain photosensitizers with high-efficiency and low toxicity. In vitro cytotoxicity tests, bacterial effect tests, and in vivo animal experiments have also demonstrated that this antibacterial method has great potential for clinical translation, with a bactericidal efficiency of up to 90%. More notably, we used this antibacterial regimen seven times repeatedly to simulate the bacterial resistance process, with a bactericidal efficiency of up to 90% every time. The result indicated that S. aureus did not develop resistance to our method, showing that our method has the potential to break through drug-resistant bacterial infections as an alternative to antibiotic candidates.

Carbon dots nanozyme for anti-inflammatory therapy via scavenging intracellular reactive oxygen species

Developing an efficient antioxidant for anti-inflammatory therapy via scavenging reactive oxygen species (ROS) remains a great challenge owing to the insufficient activity and stability of traditional antioxidants. Herein, we explored and simply synthesized a biocompatible carbon dots (CDs) nanozyme with excellent scavenging activity of ROS for anti-inflammatory therapy. As expected, CDs nanozyme effectively eliminate many kinds of free radicals including •OH, O2 •- , and ABTS+•. Benefiting from multienzyme activities against ROS, CDs nanozyme can decrease the levels of pro-inflammatory cytokines, resulting in good anti-inflammatory effect. Taken together, this study not only sheds light on design of bioactive antioxidants but also broadens the biomedical application of CDs in the treatment of inflammation.

Enhancing the Electron Transport, Quantum Yield, and Catalytic Performance of Carbonized Polymer Dots via MnO Bridges

Carbonized polymer dots (CPDs) have received tremendous attention during the last decade due to their excellent fluorescent properties and catalytic performance. Doping CPDs with transition metal atoms accelerates the local electron flow in CPDs and improves the fluorescent properties and catalytic performance of the CPDs. However, the binding sites and the formation mechanisms of the transition-metal-atom-doped CPDs remain inconclusive. In this work, Mn²⁺ -ion-doped CPDs (Mn-CPDs) are synthesized by the hydrothermal method. The Mn²⁺ ions form MnO bonds that bridge the sp² domains of carbon cores and increases the effective sp² domains in the Mn-CPDs, which redshifts the fluorescence emission peak of the Mn-CPDs slightly. The Mn²⁺ ions form covalent bonds in the CPDs and remedy the oxygen vacancies of the CPDs, which cuts off the non-radiative-recombination process of the Mn-CPDs and increases the quantum yield of the Mn-CPDs to 70%. Furthermore, the MnO bonds accelerate the electron flow between adjacent sp² domains and enhances the electron transport in the Mn-CPDs. Thus, the Mn-CPDs demonstrate excellent catalytic performance to activate hydrogen peroxide (H₂ O₂ ) and produce hydroxyl radicals (•OH) to degrade methylene blue (MB) and rhodamine B (RhB).

Carbon Nanomaterials (CNMs) and Enzymes: From Nanozymes to CNM-Enzyme Conjugates and Biodegradation

Carbon nanomaterials (CNMs) and enzymes differ significantly in terms of their physico-chemical properties-their handling and characterization require very different specialized skills. Therefore, their combination is not trivial. Numerous studies exist at the interface between these two components-especially in the area of sensing-but also involving biofuel cells, biocatalysis, and even biomedical applications including innovative therapeutic approaches and theranostics. Finally, enzymes that are capable of biodegrading CNMs have been identified, and they may play an important role in controlling the environmental fate of these structures after their use. CNMs' widespread use has created more and more opportunities for their entry into the environment, and thus it becomes increasingly important to understand how to biodegrade them. In this concise review, we will cover the progress made in the last five years on this exciting topic, focusing on the applications, and concluding with future perspectives on research combining carbon nanomaterials and enzymes.

NanoZnO-modified titanium implants for enhanced anti-bacterial activity, osteogenesis and corrosion resistance

Titanium (Ti) implants are widely used in dentistry and orthopedics owing to their excellent corrosion resistance, biocompatibility, and mechanical properties, which have gained increasing attention from the viewpoints of fundamental research and practical applications. Also, numerous studies have been carried out to fine-tune the micro/nanostructures of Ti and/or incorporate chemical elements to improve overall implant performance. Zinc oxide nanoparticles (nano-ZnO) are well-known for their good antibacterial properties and low cytotoxicity along with their ability to synergize with a variety of substances, which have received increasingly widespread attention as biomodification materials for implants. In this review, we summarize recent research progress on nano-ZnO modified Ti-implants. Their preparation methods of nano-ZnO modified Ti-implants are introduced, followed by a further presentation of the antibacterial, osteogenic, and anti-corrosion properties of these implants. Finally, challenges and future opportunities for nano-ZnO modified Ti-implants are proposed.