Selenium‐Doped Carbon Quantum Dots for Free‐Radical Scavenging

An assessment of nanotechnology-based interventions for cleaning up toxic heavy metal/metalloid-contaminated agroecosystems: Potentials and issues

Heavy metals (HMs) are among the most dangerous environmental variables for a variety of life forms, including crops. Accumulation of HMs in consumables and their subsequent transmission to the food web are serious concerns for scientific communities and policy makers. The function of essential plant cellular macromolecules is substantially hampered by HMs, which eventually have a detrimental effect on agricultural yield. Among these HMs, three were considered, i.e., arsenic, cadmium, and chromium, in this review, from agro-ecosystem perspective. Compared with conventional plant growth regulators, the use of nanoparticles (NPs) is a relatively recent, successful, and promising method among the many methods employed to address or alleviate the toxicity of HMs. The ability of NPs to reduce HM mobility in soil, reduce HM availability, enhance the ability of the apoplastic barrier to prevent HM translocation inside the plant, strengthen the plant's antioxidant system by significantly enhancing the activities of many enzymatic and nonenzymatic antioxidants, and increase the generation of specialized metabolites together support the effectiveness of NPs as stress relievers. In this review article, to assess the efficacy of various NP types in ameliorating HM toxicity in plants, we adopted a 'fusion approach', in which a machine learning-based analysis was used to systematically highlight current research trends based on which an extensive literature survey is planned. A holistic assessment of HMs and NMs was subsequently carried out to highlight the future course of action(s).

Injectable Hydrogel Loaded with CDs and FTY720 Combined with Neural Stem Cells for the Treatment of Spinal Cord Injury

Purpose

Spinal cord injury (SCI) is an incurable and disabling event that is accompanied by complex inflammation-related pathological processes, such as the production of excessive reactive oxygen species (ROS) by infiltrating inflammatory immune cells and their release into the extracellular microenvironment, resulting in extensive apoptosis of endogenous neural stem cells. In this study, we noticed the neuroregeneration-promoting effect as well as the ability of the innovative treatment method of FTY720-CDs@GelMA paired with NSCs to increase motor function recovery in a rat spinal cord injury model.

Methods

Carbon dots (CDs) and fingolimod (FTY720) were added to a hydrogel created by chemical cross-linking GelMA (FTY720-CDs@GelMA). The basic properties of FTY720-CDs@GelMA hydrogels were investigated using TEM, SEM, XPS, and FTIR. The swelling and degradation rates of FTY720-CDs@GelMA hydrogels were measured, and each group's ability to scavenge reactive oxygen species was investigated. The in vitro biocompatibility of FTY720-CDs@GelMA hydrogels was assessed using neural stem cells. The regeneration of the spinal cord and recovery of motor function in rats were studied following co-treatment of spinal cord injury using FTY720-CDs@GelMA hydrogel in combination with NSCs, utilising rats with spinal cord injuries as a model. Histological and immunofluorescence labelling were used to determine the regeneration of axons and neurons. The recovery of motor function in rats was assessed using the BBB score.

Results

The hydrogel boosted neurogenesis and axonal regeneration by eliminating excess ROS and restoring the regenerative environment. The hydrogel efficiently contained brain stem cells and demonstrated strong neuroprotective effects in vivo by lowering endogenous ROS generation and mitigating ROS-mediated oxidative stress. In a follow-up investigation, we discovered that FTY720-CDs@GelMA hydrogel could dramatically boost NSC proliferation while also promoting neuronal regeneration and synaptic formation, hence lowering cavity area.

Conclusion

Our findings suggest that the innovative treatment of FTY720-CDs@GelMA paired with NSCs can effectively improve functional recovery in SCI patients, making it a promising therapeutic alternative for SCI.

Polyacrylic Acid-Coated Selenium-Doped Carbon Dots Inhibit Ferroptosis to Alleviate Chemotherapy-Associated Acute Kidney Injury

Cisplatin-associated acute kidney injury (AKI) is a severe clinical syndrome that significantly restricts the chemotherapeutic application of cisplatin in cancer patients. Ferroptosis, a newly characterized programmed cell death driven by the lethal accumulation of lipid peroxidation, is widely reported to be involved in the pathogenesis of cisplatin-associated AKI. Targeted inhibition of ferroptosis holds great promise for developing novel therapeutics to alleviate AKI. Unfortunately, current ferroptosis inhibitors possess low bioavailability or perform non-specific accumulation in the body, making them inefficient in alleviating cisplatin-associated AKI or inadvertently reducing the anti-tumor efficacy of cisplatin, thus not suitable for clinical application. In this study, a novel selenium nanomaterial, polyacrylic acid-coated selenium-doped carbon dots (SeCD), is rationally developed. SeCD exhibits high biocompatibility and specifically accumulates in the kidney. Administration of SeCD effectively scavenges broad-spectrum reactive oxygen species and significantly facilitates GPX4 expression by releasing selenium, resulting in strong mitigation of ferroptosis in renal tubular epithelial cells and substantial alleviation of cisplatin-associated AKI, without compromising the chemotherapeutic efficacy of cisplatin. This study highlights a novel and promising therapeutic approach for the clinical prevention of AKI in cancer patients undergoing cisplatin chemotherapy.

Protective effect of carbon dots as antioxidants on intestinal inflammation by regulating oxidative stress and gut microbiota in nematodes and mouse models

Inflammatory bowel disease (IBD) is a recurrent chronic colitis disease with increasing incidence and prevalence year by year. The single efficacy and significant side effects of traditional IBD treatment drugs have promoted the flourishing development of new drugs. Inspired by many health benefits of carbon dots (CDs) based nanomedicine in biomedical applications, a metal-free carbon dots (CP-CDs) was synthesized from citric acid and polyethylene polyamine to treat colitis. Oxidative stress tests at the cellular and nematode levels demonstrated CP-CDs have good antioxidant effects, while the toxicity of CP-CDs to cells and nematodes is low. CP-CDs were further applied to dextran sodium sulfate (DSS)-induced colitis in mice models, and it was found that CP-CDs can reduce the disease activity index (DAI) score of colon tissue and restore the intestinal barrier. Further, the anti-colitis mechanisms of CP-CDs were explored, one of which is to regulate intestinal oxidative stress in inflammatory mice, further reducing the expression of inflammatory cytokines, and thus alleviating colitis. Notably, 16S rRNA sequence analysis showed that the abundance of beneficial bacteria (Ligilactobacillus and Enterorhabdus) in the intestinal tract increased, while that of harmful bacteria (unclassified_Clostridia_UCG_014) decreased after CP-CDs treatment, indicating that CP-CDs rebalancing the gut microbiota destroyed by DSS is another important mechanism. In short, these non-toxic carbon dots not only have the potential for multi-factor combined relief of colitis but also offer an alternative therapy medicine for patients suffering from IBD.

Advancing Spinal Cord Injury Bioimaging and Repair with Multifunctional Gold Nanodots Tracking

High levels of reactive oxygen species (ROS) are known to play a critical role in the secondary cascade of spinal cord injury (SCI). The scavenging of ROS has emerged as a promising approach for alleviating acute SCI. Moreover, identifying the precise location of the SCI site remains challenging. Enhancing the visualization of the spinal cord and improving the ability to distinguish the lesion site are crucial for accurate and safe treatment. Therefore, there is an urgent clinical need to develop a biomaterial that integrates diagnosis and treatment for SCI. Herein, ultra-small-sized gold nanodots (AuNDs) were designed for dual-mode imaging-guided precision treatment of SCI. The designed AuNDs demonstrate two important functions. First, they effectively scavenge ROS, inhibit oxidative stress, reduce the infiltration of inflammatory cells, and prevent apoptosis. This leads to a significant improvement in SCI repair and promotes a functional recovery after injury. Second, leveraging their excellent dual-mode imaging capabilities, the AuNDs enable rapid and accurate identification of SCI sites. The high contrast observed between the injured and adjacent uninjured areas highlights the tremendous potential of AuNDs for SCI detection. Overall, by integrating ROS scavenging and dual-mode imaging in a single biomaterial, our work on functionalized AuNDs provides a promising strategy for the clinical diagnosis and treatment of SCI.

Facile and green synthesis of chlorophyll-derived multi-color fluorescent carbonized polymer dots and their use for sensitive detection of hemin

Due to the very important role in physiological process, a simple and sensitive hemin detection method is necessarily required. Biomass-based carbonized polymer dots (CPDs) have been widely studied especially as fluorescence probe owing to the advantages of low toxicity and the variety of fluorescence color, yet there are still challenges in developing their multi-color emission property from the same raw materials. In this work, red, white and blue emissive CPDs derived from chlorophyll have been synthesized via hydrothermal method. Then white-emitted CPDs (white-CPDs) with the Commission International d'Eclairage (CIE) coordinates at (0.34, 0.32) were used to develop a fluorescence quenched sensing system for hemin determination. There is a good linear relationship between (F0-F)/F0 and concentration of hemin in the range of 0.1-0.95 μM with a detection limit of 0.043 μM, and the quenching mechanism was considered to be caused by inner filter effect (IFE). Moreover, it has been successfully used for hemin detection in serum and also for visual determination, which indicating great potential in applications of disease diagnoses and trace identification.

Current Advances on the Single-Atom Nanozyme and Its Bioapplications

Nanozymes, a class of nanomaterials mimicking the function of enzymes, have aroused much attention as the candidate in diverse fields with the arbitrarily tunable features owing to the diversity of crystalline nanostructures, composition, and surface configurations. However, the uncertainty of their active sites and the lower intrinsic deficiencies of nanomaterial-initiated catalysis compared with the natural enzymes promote the pursuing of alternatives by imitating the biological active centers. Single-atom nanozymes (SAzymes) maximize the atom utilization with the well-defined structure, providing an important bridge to investigate mechanism and the relationship between structure and catalytic activity. They have risen as the new burgeoning alternative to the natural enzyme from in vitro bioanalytical tool to in vivo therapy owing to the flexible atomic engineering structure. Here, focus is mainly on the three parts. First, a detailed overview of single-atom catalyst synthesis strategies including bottom-up and top-down approaches is given. Then, according to the structural feature of single-atom nanocatalysts, the influence factors such as central metal atom, coordination number, heteroatom doping, and the metal-support interaction are discussed and the representative biological applications (including antibacterial/antiviral performance, cancer therapy, and biosensing) are highlighted. In the end, the future perspective and challenge facing are demonstrated.

Rescuing Nucleus Pulposus Cells from ROS Toxic Microenvironment via Mitochondria-Targeted Carbon Dot-Supported Prussian Blue to Alleviate Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is invariably accompanied by excessive accumulation of reactive oxygen species (ROS), resulting in progressive deterioration of mitochondrial function and senescence in nucleus pulposus cells (NPCs). Significantly, the main ROS production site in non-immune cells is mitochondria, suggesting mitochondria is a feasible therapeutic target to reverse IVDD. Triphenylphosphine (TPP), which is known as mitochondrial-tropic ligands, is utilized to modify carbon dot-supported Prussian blue (CD-PB) to scavenge superfluous intro-cellular ROS and maintain NPCs at normal redox levels. CD-PB-TPP can effectively escape from lysosomal phagocytosis, permitting efficient mitochondrial targeting. After strikingly lessening the ROS in mitochondria via exerting antioxidant enzyme-like activities, such as superoxide dismutase, and catalase, CD-PB-TPP rescues damaged mitochondrial function and NPCs from senescence, catabolism, and inflammatory reaction in vitro. Imaging evaluation and tissue morphology assessment in vivo suggest that disc height index, mean grey values of nucleus pulposus tissue, and histological morphology are significantly improved in the IVDD model after CD-PB-TPP is locally performed. In conclusion, this study demonstrates that ROS-induced mitochondrial dysfunction and senescence of NPCs leads to IVDD and the CD-PB-TPP possesses enormous potential to rescue this pathological process through efficient removal of ROS via targeting mitochondria, supplying a neoteric strategy for IVDD treatment.

Tumor diagnosis using carbon-based quantum dots: Detection based on the hallmarks of cancer

Carbon-based quantum dots (CQDs) have been shown to have promising application value in tumor diagnosis. Their use, however, is severely hindered by the complicated nature of the nanostructures in the CQDs. Furthermore, it seems impossible to formulate the mechanisms involved using the inadequate theoretical frameworks that are currently available for CQDs. In this review, we re-consider the structure-property relationships of CQDs and summarize the current state of development of CQDs-based tumor diagnosis based on biological theories that are fully developed. The advantages and deficiencies of recent research on CQDs-based tumor diagnosis are thus explained in terms of the manifestation of nine essential changes in cell physiology. This review makes significant progress in addressing related problems encountered with other nanomaterials.

Roles of PTEN gene methylation in Se-CQDs induced mitochondrial apoptosis of osteosarcoma cells

Biocompatible carbon quantum dots (CQDs) containing anti-osteosarcoma elements are intriguing therapeutics promising for bioimaging and tumor therapy. However, how the anti-osteosarcoma element doped in the structure of such CQDs triggers tumor inhibition remains unclear. Here, selenium-doped CQDs (Se-CQDs) are developed via a one-step hydrothermal route using discarded orange peel as a carbon source and structurally characterized by various physicochemical techniques. The biocompatibility and anti-osteosarcoma efficacy are deeply evaluated using animal and cell models. The resulting spherical Se-CQDs, with a 3-7 nm diameter, possess green-yellow tunable luminescence and excellent biocompatibility. Cell experiments show that Se-CQDs can be up-taken by osteosarcoma U2OS cells and activate the mitochondrial apoptosis pathway triggered by increased reactive oxygen species. They can arrest the cell cycle at the G2/S phase and promote cellular apoptosis with reduced invasion and migration. Molecularly, Se-CQDs can down-regulate the expression of DNMT1 while up-regulating the expression of PTEN due to the decreased promoter methylation. Notably, Se-incorporated CQDs are more effective in inhibiting the proliferation, migration, and invasion of osteosarcoma than Se-free CQDs. It is feasible to use Se-CQDs as candidates for the potential application of early monitoring and treatment of osteosarcoma.

Regulating Chondro-Bone Metabolism for Treatment of Osteoarthritis via High-Permeability Micro/Nano Hydrogel Microspheres

Destruction of cartilage due to the abnormal remodeling of subchondral bone (SB) leads to osteoarthritis (OA), and restoring chondro-bone metabolic homeostasis is the key to the treatment of OA. However, traditional intra-articular injections for the treatment of OA cannot directly break through the cartilage barrier to reach SB. In this study, the hydrothermal method is used to synthesize ultra-small size (≈5 nm) selenium-doped carbon quantum dots (Se-CQDs, SC), which conjugated with triphenylphosphine (TPP) to create TPP-Se-CQDs (SCT). Further, SCT is dynamically complexed with hyaluronic acid modified with aldehyde and methacrylic anhydride (AHAMA) to construct highly permeable micro/nano hydrogel microspheres (SCT@AHAMA) for restoring chondro-bone metabolic homeostasis. In vitro experiments confirmed that the selenium atoms scavenged reactive oxygen species (ROS) from the mitochondria of mononuclear macrophages, inhibited osteoclast differentiation and function, and suppressed early chondrocyte apoptosis to maintain a balance between cartilage matrix synthesis and catabolism. In vivo experiments further demonstrated that the delivery system inhibited osteoclastogenesis and H-vessel invasion, thereby regulating the initiation and process of abnormal bone remodeling and inhibiting cartilage degeneration in SB. In conclusion, the micro/nano hydrogel microspheres based on ultra-small quantum dots facilitate the efficient penetration of articular SB and regulate chondro-bone metabolism for OA treatment.

Multifunctional Carbon Dots for Biomedical Applications: Diagnosis, Therapy, and Theranostic

Designing suitable nanomaterials is an ideal strategy to enable early diagnosis and effective treatment of diseases. Carbon dots (CDs) are luminescent carbonaceous nanoparticles that have attracted considerable attention. Through facile synthesis, they process properties including tunable light emission, low toxicity, and light energy transformation, leading to diverse applications as optically functional materials in biomedical fields. Recently, their potentials have been further explored, such as enzyme-like activity and ability to promote osteogenic differentiation. Through refined synthesizing strategies carbon dots, a rich treasure trove for new discoveries, stand a chance to guide significant development in biomedical applications. In this review, the authors start with a brief introduction to CDs. By presenting mechanisms and examples, the authors focus on how they can be used in diagnosing and treating diseases, including bioimaging failure of tissues and cells, biosensing various pathogenic factors and biomarkers, tissue defect repair, anti-inflammation, antibacterial and antiviral, and novel oncology treatment. The introduction of the application of integrated diagnosis and treatment follows closely behind. Furthermore, the challenges and future directions of CDs are discussed. The authors hope this review will provide critical perspectives to inspire new discoveries on CDs and prompt their advances in biomedical applications.

Moderate selenium mitigates hand grip strength impairment associated with elevated blood cadmium and lead levels in middle-aged and elderly individuals: insights from NHANES 2011-2014

Background: Selenium (Se) has been reported to have an antagonistic effect on heavy metals in animals. Nevertheless, there is a lack of epidemiological research examining whether Se can mitigate the adverse effects of cadmium (Cd) and lead (Pb) on hand grip strength (HGS) in middle-aged and elderly individuals. Methods: This study used data from the 2011-2014 National Health and Nutrition Examination Survey (NHANES). HGS measurements were conducted by trained examiners with a dynamometer. Concentrations of Se, Cd, and Pb in blood were determined via inductively coupled plasma mass spectrometry. We employed linear regression, restricted cubic splines, and quantile g-computation (qgcomp) to assess individual and combined associations between heavy metals and HGS. The study also explored the potential influence of Se on these associations. Results: In both individual metal and multi-metal models adjusted for confounders, general linear regression showed Se's positive association with HGS, while Cd and Pb inversely related to it. At varying Se-Cd and Se-Pb concentrations, high Se relative to low Se can attenuate Cd and Pb's HGS impact. An inverted U-shaped correlation exists between Se and both maximum and combined HGS, with Se's benefit plateauing beyond approximately 200 μg/L. Stratified analysis by Se quartiles reveals Cd and Pb's adverse HGS effects diminishing as Se levels increase. Qgcomp regression analysis detected Se alleviating HGS damage from combined Cd and Pb exposure. Subsequent subgroup analyses identified the sensitivity of women, the elderly, and those at risk of diabetes to HGS impairment caused by heavy metals, with moderate Se supplementation beneficial in mitigating this effect. In the population at risk for diabetes, the protective role of Se against heavy metal toxicity-induced HGS reduction is inhibited, suggesting that diabetic individuals should particularly avoid heavy metal-induced handgrip impairment. Conclusion: Blood Cd and Pb levels are negatively correlated with HGS. Se can mitigate this negative impact, but its effectiveness plateaus beyond 200 μg/L. Women, the elderly, and those at risk of diabetes are more vulnerable to HGS damage from heavy metals. While Se supplementation can help, its protective effect is limited in high diabetes risk groups.

Selenium and nitrogen co-doped carbon dots with highly efficient electrochemiluminescence for ultrasensitive detection of microRNA

In this work, selenium and nitrogen co-doped carbon dots (SeN-CDs) possessing highly efficient electrochemiluminescence (ECL) and excellent biocompatibility were synthesized as a new emitter with S2O82- as a coreactant for constructing a biosensor to detect microRNA-221 (miRNA-221) sensitively. Notably, the SeN-CDs exhibited superior ECL performance compared with the N-doped CDs, in which selenium with excellent redox activity served as a coreaction accelerator for facilitating the electroreduction of S2O82- to significantly improve ECL efficiency. Furthermore, target-induced T7 exonuclease (T7 Exo)-assisted double cycle amplification strategy could convert traces of target miRNA-221 into large amounts of output DNA to capture three-dimensional (3D) nanostructures (DTN-Au NPs-DOX-Fc) loaded with large amounts of ECL signal quencher. The constructed biosensor could realize ultrasensitive detection of miRNA-221 and has a low detection limit reaching 2.3 aM, with a successful application to detect miRNA-221 in lysate of Hela and MHCC97-L cancer cell. This work explored a novel method to strengthen the ECL performance of CDs to construct an ECL biosensing platform with sensitive detecting of biomarkers and disease diagnosis.

Ultra-fast solvent-free protocol remodels the large-scale synthesis of carbon dots for nucleolus-targeting and white light-emitting diodes

Carbon dots (CDs) provides unprecedented opportunities for optical applications due its unique properties, but the energy-extensive consumption, high-risk factor and time-consuming synthesis procedure greatly hinders its industrialization process. Herein, we proposed an ultra-low energy consumption solvent-free synthetic strategy for fast preparing green/red fluorescence carbon dots (G-/R-CDs) using m-/o-phenylenediamine and primary amine hydrochloride. The involvement of primary amine hydrochloride can improve the formation rate of G-CDs/R-CDs through effectively absorbing microwave energy and providing acid react environment. The developed CDs exhibit good fluorescence efficiency, optical stability and membrane permeability for dexterous bioimaging in vivo. Based on inherently high nitrogen content, the G-CDs/R-CDs possess excellent nuclear/nucleolus targeting ability, and were successfully applied for screening cancer and normal cells. Furthermore, the G-CDs/R-CDs were further applied for fabricating high-safety and high-color rendering index white light-emitting diodes, providing a perfect candidate for indoor lighting. This study opens up new horizons for advancing practical applications of CDs in related fields of biology and optics.

Reactive X (where X = O, N, S, C, Cl, Br, and I) species nanomedicine

Reactive oxygen, nitrogen, sulfur, carbonyl, chlorine, bromine, and iodine species (RXS, where X = O, N, S, C, Cl, Br, and I) have important roles in various normal physiological processes and act as essential regulators of cell metabolism; their inherent biological activities govern cell signaling, immune balance, and tissue homeostasis. However, an imbalance between RXS production and consumption will induce the occurrence and development of various diseases. Due to the considerable progress of nanomedicine, a variety of nanosystems that can regulate RXS has been rationally designed and engineered for restoring RXS balance to halt the pathological processes of different diseases. The invention of radical-regulating nanomaterials creates the possibility of intriguing projects for disease treatment and promotes advances in nanomedicine. In this comprehensive review, we summarize, discuss, and highlight very-recent advances in RXS-based nanomedicine for versatile disease treatments. This review particularly focuses on the types and pathological effects of these reactive species and explores the biological effects of RXS-based nanomaterials, accompanied by a discussion and the outlook of the challenges faced and future clinical translations of RXS nanomedicines.

Design of a Synthetic Strategy to Achieve Enhanced Fluorescent Carbon Dots with Sulfur and Nitrogen Codoping and Its Multifunctional Applications

Here, a rational strategy to achieve multifunctional N, S codoped carbon dots (N, S-CDs) is reported, aiming to improve the photoluminescence quantum yields (PLQYs) of the CDs. The synthesized N, S-CDs have excellent stability and emission properties independent of excitation wavelength. Through the introduction of S element doping, the fluorescence emission of CDs is red-shifted from 430 to 545 nm, and the corresponding PLQYs can be greatly enhanced from 11.2% to 65.1%. It is found that the doping of S elements causes an increase in the size of CDs and an elevated graphite N content, which may be the key factors to cause the redshift of fluorescence emission. Furthermore, the introduction of S element also serves to suppress the nonradiative transitions, which may be responsible for the elevated PLQYs. Besides, the synthesized N, S-CDs have certain solvent effect and can be applied to detect water content in organic solvents, and have strong sensitivity to alkaline environment. More importantly, the N, S-CDs can be used to achieve an "on-off-on" dual detection mode between Zr4+ and NO2 - . In addition, N, S-CDs combinedwith polyvinylpyrrolidone (PVP) can also be utilized as fluorescent inks for anti-counterfeiting applications.

Luminescence of carbon quantum dots and their application in biochemistry

Similar to fullerenes, carbon nanotubes and graphene, carbon dots (CDs) are causing a lot of research work in their own right. CDs are a type of surface-passivated quantum dot that contain carbon atoms. Their distinctive characteristics, such as luminescent emission that varies with size and wavelength, resistance to photobleaching, easy biological binding, lack of toxicity, and economical production without the need for intricate synthetic processes, have led to a noteworthy surge in attention within the research community. Different techniques can be utilized to create these CDs, spanning from basic candle burning to laser ablation. This review article delves into the principles of fluorescence technology, providing insights into how different synthesis methods of quantum dots impact their luminescent properties. Additionally, it highlights the latest applications of quantum dots in catalysis and biomedical fields, with special emphasis on the current status of luminescent properties in biology and chemistry. Towards the end, the article discusses the limitations of quantum dots in current practical applications, pointing out that CDs hold promising potential for future applications.

X-Ray-Induced Drug Release for Cancer Therapy

Drug delivery systems (DDSs) are designed to deliver therapeutic agents to specific target sites while minimizing systemic toxicity. Recent developments in drug-loaded DDSs have demonstrated promising characteristics and paved new pathways for cancer treatment. Light, a prevalent external stimulus, is widely utilized to trigger drug release. However, conventional light sources primarily concentrate on the ultraviolet (UV) and visible light regions, which suffer from limited biological tissue penetration. This limitation hinders applications for deep-tissue tumor drug release. Given their deep tissue penetration and well-established application technology, X-rays have recently received attention for the pursuit of controlled drug release. With precise spatiotemporal and dosage controllability, X-rays stand as an ideal stimulus for achieving controlled drug release in deep-tissue cancer therapy. This article explores the recent advancements in using X-rays for stimulus-triggered drug release in DDSs and delves into their action mechanisms.

N-Acetylcysteine-Derived Carbon Dots for Free Radical Scavenging in Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is associated with oxidative stress induced reactive oxygen species (ROS) dynamic equilibrium disturbance. Nanozymes, as nanomaterials with enzyme-like activity, can regulate intro-cellular ROS levels. In this study, a new carbon dots nanozyme, N-acetylcysteine-derived carbon dots (NAC-CDs), is developed and proved to be an ideal antioxidant and anti-senescent agent in IVDD management. The results confirmed the NAC-CDs have satisfactory biocompatibility and strong superoxide dismutase (250 U mg-1 ), catalase, glutathioneperoxidase-like activity, and total antioxidant capacity. Then, the powerful free radical scavenging and antioxidant ability of NAC-CDs are demonstrated in vitro as observing the reduced ROS in H2 O2 induced senescent nucleus pulposus cells (NPCs), in which the elimination efficiency of toxic ROS is more than 90%. NAC-CDs also maintained mitochondrial homeostasis and suppressed cellular senescence, subsequently inhibited the expression of inflammatory factors in NPCs. In vivo, evaluations of imaging and tissue morphology assessments suggested that disc height index, magnetic resonance imaging grade and histological score are significantly improved from the degenerative models when NAC-CDs is applied. In conclusion, the study developed a novel carbon dots nanozyme, which efficiently rescues IVDD from ROS induced NPCs senescence and provides a potential strategy in management of IVDD in clinic.

Mackinawite nanozymes as reactive oxygen species scavengers for acute kidney injury alleviation

BACKGROUND

Iron sulfide nanomaterials have been successfully employed as therapeutic agents for bacterial infection therapy and catalytic-ferroptosis synergistic tumor therapy due to their unique structures, physiochemical properties, and biocompatibility. However, biomedical research and understanding of the biological functions of iron sulfides are insufficient, and how iron sulfide nanomaterials affect reactive oxygen species (ROS) in diseases remains unknown. Acute kidney injury (AKI) is associated with high levels of ROS, and therefore nanomedicine-mediated antioxidant therapy has emerged as a novel strategy for its alleviation.

RESULTS

Here, mackinawite nanozymes were synthesized from glutathione (GSH) and iron ions (Fe3+) (denoted as GFeSNs) using a hydrothermal method, and then evaluated as ROS scavengers for ROS-related AKI treatment. GFeSNs showed broad-spectrum ROS scavenging ability through synergistic interactions of multiple enzymes-like and hydrogen polysulfide-releasing properties. Furthermore, both in vitro and in vivo experiments demonstrated that GFeSNs exhibited outstanding cytoprotective effects against ROS-induced damage at extremely low doses and significantly improved treatment outcomes in AKI.

CONCLUSIONS

Given the synergetic antioxidant properties and high biocompatibility, GFeSNs exhibit great potential for the treatment of AKI and other ROS-associated diseases.

Antioxidant and Prooxidant Nanozymes: From Cellular Redox Regulation to Next-Generation Therapeutics

Nanozymes, nanomaterials with enzyme-mimicking activity, have attracted tremendous interest in recent years owing to their ability to replace natural enzymes in various biomedical applications, such as biosensing, therapeutics, drug delivery, and bioimaging. In particular, the nanozymes capable of regulating the cellular redox status by mimicking the antioxidant enzymes in mammalian cells are of great therapeutic significance in oxidative-stress-mediated disorders. As the distinction of physiological oxidative stress (oxidative eustress) and pathological oxidative stress (oxidative distress) occurs at a fine borderline, it is a great challenge to design nanozymes that can differentially sense the two extremes in cells, tissues and organs and mediate appropriate redox chemical reactions. In this Review, we summarize the advances in the development of redox-active nanozymes and their biomedical applications. We primarily highlight the therapeutic significance of the antioxidant and prooxidant nanozymes in various disease model systems, such as cancer, neurodegeneration, and cardiovascular diseases. The future perspectives of this emerging area of research and the challenges associated with the biomedical applications of nanozymes are described.

Atomic vacancies-engineered ultrathin trimetallic nanozyme with anti-inflammation and antitumor performances for intestinal disease treatment

Colitis-associated colorectal cancer, which represents a highly aggressive subtypes of colorectal cancer, requires concurrent antitumor and anti-inflammation therapies in clinic. Herein, we successfully engineered Ru38Pd34Ni28 ultrathin trimetallic nanosheets (TMNSs) by introducing diverse transition metal atoms into the structure of RuPd nanosheets. Density functional theory (DFT) calculations reveal that the elaborate introduction of transition metal Ru and Ni facilitates the formation of Ru-O and Ni-O bonds on the surface of TMNSs for efficient reactive oxygen species (ROS) and reactive nitrogen species (RNS) scavenging, respectively. Moreover, the engineered abundant atomic vacancies on their surface conspicuously improve the performance in eliminating reactive oxygen and nitrogen species (RONS). The designed TMNSs act as a multi-metallic nanocatalyst with RONS elimination performance for chronic colitis treatment by relieving inflammation, as well as photothermal conversion capability for colon cancer therapy by inducing hyperthermia effect. Profiting from the excellent RONS scavenging activities, TMNSs can down-regulate the expression levels of the pro-inflammatory factors, thereby leading to prominent therapeutic efficacy against dextran sulfate sodium-induced colitis. Benefiting from the high photothermal performance, TMNSs cause significant suppression of CT-26 tumors without obvious recurrence. This work provides a distinct paradigm to design multi-metallic nanozymes for colon disease treatment by elaborate introduction of transition metal atoms and engineering of atomic vacancies.

Emergency Treatment and Photoacoustic Assessment of Spinal Cord Injury Using Reversible Dual-Signal Transform-Based Selenium Antioxidant

Spinal cord injury (SCI), following explosive oxidative stress, causes an abrupt and irreversible pathological deterioration of the central nervous system. Thus, preventing secondary injuries caused by reactive oxygen species (ROS), as well as monitoring and assessing the recovery from SCI are critical for the emergency treatment of SCI. Herein, an emergency treatment strategy is developed for SCI based on the selenium (Se) matrix antioxidant system to effectively inhibit oxidative stress-induced damage and simultaneously real-time evaluate the severity of SCI using a reversible dual-photoacoustic signal (680 and 750 nm). Within the emergency treatment and photoacoustic severity assessment (ETPSA) strategy, the designed Se loaded boron dipyrromethene dye with a double hydroxyl group (Se@BDP-DOH) is simultaneously used as a sensitive reporter group and an excellent antioxidant for effectively eliminating explosive oxidative stress. Se@BDP-DOH is found to promote the recovery of both spinal cord tissue and locomotor function in mice with SCI. Furthermore, ETPSA strategy synergistically enhanced ROS consumption via the caveolin 1 (Cav 1)-related pathways, as confirmed upon treatment with Cav 1 siRNA. Therefore, the ETPSA strategy is a potential tool for improving emergency treatment and photoacoustic assessment of SCI.

Biogenic Carbon Quantum Dots as a Neoteric Inducer in the Game of Directing Chondrogenesis

The journey into the field of stem cell biology has been an endeavor of paramount advancement in biomedicine, establishing new horizons in the avenue of materiobiology. The creative drive of the scientific community focuses on ameliorating the utilization of stem cells, which is currently untapped on a large scale. With similar motivation, we present a nascent strategy of maneuvering biogenic carbon quantum dots (CQDs) to eclipse the toxic hurdles of chemical synthesis of carbon allotropes to serve as a biocompatible trident in stem cell biology employing a three-prong action of stem cell differentiation, imaging, and migration. The derivation of CQDs from garlic peels as a biogenic precursor abets in realizing the optophysical features of CQDs to image mesenchymal stem cells without hampering the biological systems with cytotoxicity. We report the versatility of biogenic CQDs to generate reactive oxygen species (ROS) to robustly influence stem cell migration and concomitantly chondrocyte differentiation from human Wharton's jelly mesenchymal stem cells (hWJ-MSCs). This was orchestrated without the use of chondrogenic induction factors, which was confirmed from the expression of chondrogenic markers (Col II, Col X, ACAN). Even the collagen content of cells incubated with CQDs was quite comparable with that of chondrocyte-induced cells. Thus, we empirically propose garlic peel-derived CQDs as a tangible advancement in stem cell biology from a materiobiological frame of reference to hone significant development in this arena.

Self-Assembly of Selenium-Doped Carbon Quantum Dots as Antioxidants for Hepatic Ischemia-Reperfusion Injury Management

Hepatic ischemia-reperfusion injury (HIRI) is a critical complication after liver surgery that negatively affects surgical outcomes of patients with the end-stage liver-related disease. Reactive oxygen species (ROS) are responsible for the development of ischemia-reperfusion injury and eventually lead to hepatic dysfunction. Selenium-doped carbon quantum dots (Se-CQDs) with an excellent redox-responsive property can effectively scavenge ROS and protect cells from oxidation. However, the accumulation of Se-CQDs in the liver is extremely low. To address this concern, the fabrication of Se-CQDs-lecithin nanoparticles (Se-LEC NPs) is developed through self-assembly mainly driven by the noncovalent interactions. Lecithin acting as the self-assembly building block also makes a pivotal contribution to the therapeutic performance of Se-LEC NPs due to its capability to react with ROS. The fabricated Se-LEC NPs largely accumulate in the liver, effectively scavenge ROS and inhibit the release of inflammatory cytokines, thus exerting beneficial therapeutic efficacy on HIRI. This work may open a new avenue for the design of self-assembled Se-CQDs NPs for the treatment of HIRI and other ROS-related diseases.

Carbon Dots Based Photoinduced Reactions: Advances and Perspective

Seeking clean energy as an alternative to traditional fossil fuels is the inevitable choice to realize the sustainable development of the society. Photocatalytic technique is considered a promising energy conversion approach to store the abundant solar energy into other wieldy energy carriers like chemical energy. Carbon dots, as a class of fascinating carbon nanomaterials, have already become the hotspots in numerous photoelectric researching fields and particularly drawn keen interests as metal-free photocatalysts owing to strong UV-vis optical absorption, tunable energy-level configuration, superior charge transfer ability, excellent physicochemical stability, facile fabrication, low toxicity, and high solubility. In this review, the classification, microstructures, general synthetic methods, optical and photoelectrical properties of carbon dots are systematically summarized. In addition, recent advances of carbon dots based photoinduced reactions including photodegradation, photocatalytic hydrogen generation, CO₂ conversion, N₂ fixation, and photochemical synthesis are highlighted in detail, deep insights into the roles of carbon dots in various systems combining with the photocatalytic mechanisms are provided. Finally, several critical issues remaining in photocatalysis field are also proposed.

Selenium-decorated biocompatible honeycomb films with redox-switchable surface for controlling cell adhesion/detachment

HYPOTHESIS

Selenium (Se)-containing compound is sensitive to redox stimulation, showing hydrophobic-hydrophilic reversible transition. Introduction of such compound into honeycomb film could confer on it redox-switchable surface wettability, which is expected to control cell adhesion/detachment behavior.

EXPERIMENTS

Didodecyl selenide was designed and mixed with polystyrene to prepare honeycomb films using "breath figure" method. The film microstructures were characterized by scanning electron microscope and atomic force microscopy, and the arrangement of Se atoms in honeycomb film was determined by X-ray photoelectron spectroscopy and energy dispersive spectrometry. The variation of film wettability upon the alternating stimulation of H₂O₂ and Vc was examined. Then the cell adhesion, proliferation, and controlled detachment on honeycomb films were conducted.

FINDINGS

The introduction of didodecyl selenide helps to form ordered honeycomb film, and Se atoms were found to located on the bottom, pore walls, and top surface of the film. The presence of didodecyl selenide not only greatly improves film biocompatibility by enhancing cell thioredoxin reductase activity, but also imparts the film with H₂O₂-/vitamin C-regulated tunable wettability that controls cell adhesion and detachment. H₂O₂ treatment produces a hydrophilic surface for cell adhesion and proliferation, whereas the addition of vitamin C generates hydrophobic surfaces and allows cells to detach while remaining alive with high activity.

Flame-Retardant and Self-Healing Waterborne Polyurethane Based on Organic Selenium

Waterborne polyurethane has drawn extensive attention due to its environmental friendliness and is widely used in many areas. However, it is still a great challenge to synthesize waterborne polyurethanes with flame retardancy and fast room-temperature self-healing ability, along with excellent mechanical performance and emulsion stability due to the mutually contradictory nature of these properties. Herein, waterborne polyurethanes containing organic selenium (SWPU-x) from 0.67 to 3.28 wt % were synthesized, which could simultaneously realize flame retardancy and self-healing ability based on the ability to scavenge active free radicals at high temperature and the dynamic switch of diselenide. All these SWPU-x films self-extinguished within 1 s after the ignition in the vertical combustion tests. The limiting oxygen index of SWPU-4 was improved to 28.5% with excellent UL-94 level (V-0) and self-healing efficiency (91.25%, after being healed in the photoreactor for 30 min at room temperature), together with high mechanical properties (tensile strength was 18.5 MPa and elongation at break was 869.63%), and the total heat release (THR) for SWPU-4 (49.28 MJ/m²) could decrease to 23.80% of the THR for the original waterborne polyurethane WPU (64.67 MJ/m²). This work discovered a new flame-retardant element (organic selenium) and studied its flame-retardant behaviors and self-healing function simultaneously, which would extremely extend the application of waterborne polyurethanes.

Hydrothermally Derived Green Carbon Dots from Broccoli Water Extracts: Decreased Toxicity, Enhanced Free-Radical Scavenging, and Anti-Inflammatory Performance

Biomass carbon dots (CDs) derived from natural plants possess the advantages of low cost, photostability, and excellent biocompatibility, with potential applications in chemical sensing, bioimaging, and nanomedicine. However, the development of biomass CDs with excellent antioxidant activity and good biocompatibility is still a challenge. Herein, we propose a hypothesis for enhancing the antioxidant capacity of biomass CDs based on precursor optimization, extraction solvent, and other conditions with broccoli as the biomass. Compared to broccoli water extracts, broccoli powders, and broccoli organic solvent extracts, CDs derived from broccoli water extracts (BWE-CDs) have outstanding antioxidant properties due to the abundant C═C, carbonyl, and amino groups on their surface. After optimization of the preparation condition, the obtained BWE-CDs exhibit excellent free-radical scavenging activity with an EC₅₀ of 68.2 μg/mL for DPPH^• and 22.4 μg/mL for ABTS^•+. Cytotoxicity and zebrafish embryotoxicity results indicated that BWE-CDs have lower cytotoxicity and better biocompatibility than that of CDs derived from organic solvents. In addition, BWE-CDs effectively scavenged reactive oxygen species (ROS) in A549 cells, 293T cells, and zebrafish, as well as eliminating inflammation in LPS-stimulated zebrafish. Mechanistic studies showed that the anti-inflammatory effect of BWE-CDs was dependent on the direct reaction of CDs with free radicals, the regulation of NO levels, and the upregulation of the expression of SOD and GPX-4. This work indicates that the antioxidant activity of CDs could be enhanced by using solvent extracts of biomass as precursors, and the obtained BWE-CDs exhibit characteristics of greenness, low toxicity, and excellent antioxidant and anti-inflammatory activities, which suggests the potential promising application of BWE-CDs as an antioxidant nanomedicine for inflammatory therapy.

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.

Recent advances of antioxidant low-dimensional carbon materials for biomedical applications

As the primary cause of many tissue damage and diseases, reactive oxygen species (ROS) and reactive nitrogen species (RNS) are well known to be extremely harmful to a variety of biological components in cells including lipids, proteins and DNA. Numerous antioxidative nanomaterials have been artificially designed and rationally synthesized to protect cells from the oxidative damage caused by reactive oxygen species/reactive nitrogen species. Recent studies demonstrate that low dimensional carbon antioxidative nanomaterials have received a lot of attention owing to their tiny nanoscales and unique physicochemical property. As a result, a brief overview of recent advancements in antioxidant low-dimensional carbon materials is provided. Typically, carbon nanomaterials are classified according to their nanostructure dimensions, which are zero-dimension, one-dimension, and two-dimension. Last but not least, the challenges and perspectives of these high-performance low-dimensional materials in biomedical fields and further clinical usages are discussed as well.

Synthesis, characterization and potential sensing application of carbon dots synthesized via the hydrothermal treatment of cow milk

Carbon quantum dots (CQDs) were synthesized in this study by hydrothermally treating cow milk. The procedure is simple, non-hazardous to the environment, and does not necessitate the use of any special instruments or chemicals. CQDs were practically almost circular when they were manufactured and had an average size of 7 nm. Carbon (67.36%), oxygen (22.73%), and nitrogen (9.91%) comprised the majority of their composition. They feature broad excitation-emission spectra, excitation-dependent emission, and temperature-dependent photoluminescence. They remained quite stable in the presence of a lot of salt, UV radiation, and storage time. Because luminescence quenching mechanisms are sensitive to and selective for Sn²⁺, they can be employed to create a nanosensor for detecting Sn²⁺.

Advanced nanomaterials for modulating Alzheimer's related amyloid aggregation

Alzheimer's disease (AD) is a common neurodegenerative disease that brings about enormous economic pressure to families and society. Inhibiting abnormal aggregation of Aβ and accelerating the dissociation of aggregates is treated as an effective method to prevent and treat AD. Recently, nanomaterials have been applied in AD treatment due to their excellent physicochemical properties and drug activity. As a drug delivery platform or inhibitor, various excellent nanomaterials have exhibited potential in inhibiting Aβ fibrillation, disaggregating, and clearing mature amyloid plaques by enhancing the performance of drugs. This review comprehensively summarizes the advantages and disadvantages of nanomaterials in modulating amyloid aggregation and AD treatment. The design of various functional nanomaterials is discussed, and the strategies for improved properties toward AD treatment are analyzed. Finally, the challenges faced by nanomaterials with different dimensions in AD-related amyloid aggregate modulation are expounded, and the prospects of nanomaterials are proposed.

Recent advances in nanomaterials for the treatment of spinal cord injury

Spinal cord injuries (SCIs) are devastating. In SCIs, a powerful traumatic force impacting the spinal cord results in the permanent loss of nerve function below the injury level, leaving the patient paralyzed and wheelchair-bound for the remainder of his/her life. Unfortunately, clinical treatment that depends on surgical decompression appears to be unable to handle damaged nerves, and high-dose methylprednisolone-based therapy is also associated with problems, such as infection, gastrointestinal bleeding, femoral head necrosis, obesity, and hyperglycemia. Nanomaterials have opened new avenues for SCI treatment. Among them, performance-based nanomaterials derived from a variety of materials facilitate improvements in the microenvironment of traumatic injury and, in some cases, promote neuron regeneration. Nanoparticulate drug delivery systems enable the optimization of drug effects and drug bioavailability, thus contributing to the development of novel treatments. The improved efficiency and accuracy of gene delivery will also benefit the exploration of SCI mechanisms and the understanding of key genes and signaling pathways. Herein, we reviewed different types of nanomaterials applied to the treatment of SCI and summarized their functions and advantages to provide new perspectives for future clinical therapies.

Nitrogen and boron co-doped carbon dots as a novel fluorescent probe for fluorogenic sensing of Ce4+ and ratiometric detection of Al3

Carbon dots have been widely focused on the field of metal ion detection due to their excellent optical property. Herein, novel orange fluorescent nitrogen and boron co-doped carbon dots (NB-CDs) are obtained by one-pot solvothermal using p-phenylenediamine and boric acid as raw materials. The NB-CDs exhibit excitation-independent emissions and the maximum emission wavelength is 597 nm at 420 nm excitation. The fluorescence can be quenched by Ce⁴⁺ effectively and selectively, and the detection range of Ce⁴⁺ is gained from 0.14 to 180 μM with a detection limit of as low as 0.14 μM. Furthermore, Al³⁺ can also recombine with NB-CDs surface functional groups, which shows a detection range from 1.07 to 100 μM and a detection limit of as low as 1.07 μM, accompanied with a blue-shift to 527 nm.

Low dimensional nanomaterials for treating acute kidney injury

Acute kidney injury (AKI) is one of the most common severe complications among hospitalized patients. In the absence of specific drugs to treat AKI, hemodialysis remains the primary clinical treatment for AKI patients. AKI treatment has received significant attention recently due to the excellent drug delivery capabilities of low-dimensional nanomaterials (LDNs) and their unique therapeutic effects. Diverse LDNs have been proposed to treat AKI, with promising results and the potential for future clinical application. This article aims to provide an overview of the pathogenesis of AKI and the recent advances in the treatment of AKI using different types of LDNs. In addition, it is intended to provide theoretical support for the design of LDNs and implications for AKI treatment.

Multifunctional N,S-doped and methionine functionalized carbon dots for on-off-on Fe3+ and ascorbic acid sensing, cell imaging, and fluorescent ink applying

Fluorescent carbon dots (CDs) have been identified as potential nanosensors and attracted tremendous research interests in wide areas including anti-counterfeiting, environmental and biological sensing and imaging in considering of the attractive optical properties. In this work, we present a CDs based fluorescent sensor from polyvinylpyrrolidone, citric acid, and methionine as precursors by hydrothermal approach. The selective quantifying of Fe3+ and ascorbic acid (AA) are based on the fluorescent on-off-on process, in which the fluorescent quenching is induced by the coordination of the Fe3+ on the surface of the CDs, while the fluorescence recovery is mainly attributed to redox reaction between Fe3+ and AA, breaking the coordination and bringing the fluorescence back. Inspired by the good water solubility and biocompatibility, significant photostability, superior photobleaching resistance as well as high selectivity, sensitivity, and interference immunity, which are constructed mainly from the N,S-doping and methionine surface functionalization, the CDs have not only been employed as fluorescence ink in multiple anti-counterfeiting printing and confidential document writing or transmitting, but also been developed as promising fluorescence sensors in solution and solid by CDs doped test strips and hydrogels for effectively monitoring and removing of Fe3+ and AA in environmental aqueous solution. The CDs have been also implemented as effective diagnostic candidates for imaging and tracking of Fe3+ and AA in living cells, accelerating the understanding of their function and importance in related biological processes for the prevention and treatment specific diseases.

Electronic Supplementary Material

Supplementary material (fluorescence spectra: UV and Xe irradiation, TG, thermo stability, ionic strength, relationship between fluorescence responses at different concentrations of Fe3+ and AA, reaction time-dependent fluorescent responses; XPS spectra of CDs + Fe3+ and Fe3+@CDs + AA; structural characterization; equations about fluorescence lifetime, quantum yield and LOD; comparison of the CDs for the detection of Fe3+ and AA with reported methods; detection of Fe3+ and AA in real samples; absorption of Fe3+ in environmental samples and MTT assay results) is available in the online version of this article at 10.1007/s12274-022-5107-7.

Metal-Free SeBN Ternary-Doped Porous Carbon as Efficient Electrocatalysts for CO2 Reduction Reaction

Cost-effective heteroatom-doped porous carbons are considered promising electrocatalysts for CO₂ reduction reaction (CO₂RR). Traditionally porous carbons with N doping or N/X codoping (X denotes the second type of heteroatom) have been widely studied, leaving ternary doping a much less studied yet exciting topic to be explored. Herein, a series of electrocatalysts based on metal-free Se, B, and N ternary-doped porous carbons (termed "SeBN-Cs") were synthesized and tested as metal-free electrocatalysts in CO₂RR. Our study indicates that the major product of CO₂RR on the SeBN-C electrocatalysts was CO with a small fraction (<5%) of H₂ as the byproduct. The optimal electrocatalyst sample SeBN-C-1100 prepared at 1100 °C exhibits a high CO selectivity with a Faradaic efficiency of CO reaching 95.2%. After 10 h of continuous electrolysis operation, the Faradaic efficiency and the current density are maintained high at 97.6 and 84.7% of the initial values, respectively, indicative of a long-term operational stability. This study provides an excellent reference to deepen our understanding of the properties and functions of multi-heteroatom-doped porous carbon electrocatalysts in CO₂RR.

Protein-Mimicking Nanoparticles in Biosystems

Proteins are essential elements for almost all life activities. The emergence of nanotechnology offers innovative strategies to create a diversity of nanoparticles (NPs) with intrinsic capacities of mimicking the functions of proteins. These artificial mimics are produced in a cost-efficient and controllable manner, with their protein-mimicking performances comparable or superior to those of natural proteins. Moreover, they can be endowed with additional functionalities that are absent in natural proteins, such as cargo loading, active targeting, membrane penetrating, and multistimuli responding. Therefore, protein-mimicking NPs have been utilized more and more often in biosystems for a wide range of applications including detection, imaging, diagnosis, and therapy. To highlight recent progress in this broad field, herein, representative protein-mimicking NPs that fall into one of the four distinct categories are summarized: mimics of enzymes (nanozymes), mimics of fluorescent proteins, NPs with high affinity binding to specific proteins or DNA sequences, and mimics of protein scaffolds. This review covers their subclassifications, characteristic features, functioning mechanisms, as well as the extensive exploitation of their great potential for biological and biomedical purposes. Finally, the challenges and prospects in future development of protein-mimicking NPs are discussed.

Inorganic quantum dots - anammox consortia hybrid for stable nitrogen elimination under high-intensity solar-simulated irradiation

External stimulus such as light irradiation is able to deteriorate intracellular redox homeostasis and induce photooxidative damage to non-photogenic bacteria. Exploiting effective strategies to help bacteria resisting infaust stress is meaningful for achieving a stable operation of biological treatment system. In this work, selenium-doped carbon quantum dots (Se-CQDs) were blended into anaerobic ammonia oxidation (anammox) bacteria and an inorganic nanoparticle-microbe hybrid was successfully fabricated to evaluate its nitrogen removal performance under solar-simulated irradiation. It was found that the specific anammox activity decreased by 29.7 ± 5.2% and reactive oxygen species (ROS) content increased by 134.8 ± 4.1% under 50,000 lux light. Sludge activity could be completely recovered under the optimum dosage of 0.42 mL·(g volatile suspended solid) ^-1 Se-CQDs. Hydroxyl radical (·OH) and superoxide anion radical (·O₂^-) were identified as the leading ROS inducing lipid peroxidation and antioxidase function detriment. Also, the structure of ladderane lipids located on anammoxosome was destroyed by ROS and functional genes abundances declined accordingly. Although cell surface coated Se-CQDs could absorb ultraviolet light and partially mitigated the photoinhibition, the direct scavenging of ROS by intracellular Se-CQDs primarily contributed to the cellular redox homeostasis, antioxidase activity recovery and sludge activity improvement. The findings of this work provide in-depth understanding the metabolic response mechanism of anammox consortia to light irradiation and might be valuable for a more stable and sustainable nitrogen removal technology, i.e., algal-bacterial symbiotic system, development.

Design of Diselenide-Bridged Hyaluronic Acid Nano-antioxidant for Efficient ROS Scavenging to Relieve Colitis

Overproduction of reactive oxygen species (ROS), a key characteristic of inflammatory bowel disease (IBD), is responsible for dysregulation of signal transduction, inflammatory response, and DNA damage, which ultimately leads to disease progression and deterioration. Thus, ROS scavenging has become a promising strategy to navigate IBD. Inspired by the targeting capability of hyaluronic acid (HA) to CD44-overexpressed inflammatory cells together with the redox regulation capacity of diselenide compounds, we developed an oral nanoformulation, i.e., diselenide-bridged hyaluronic acid nanogel (SeNG), with a view to treat colitis through a ROS scavenging mechanism. Our data demonstrated that SeNG specifically accumulated in colitis tissue that was mediated by highly efficient CD44-HA interaction. This has allowed us to demonstrate a significant anti-inflammatory effect in an acute colitis mouse model induced by dextran sulfate sodium and trinitrobenzenesulfonic acid. Mechanistically, we continued to show SeNG reduced the ROS level via both direct elimination and up-regulation of the Nrf2/HO-1 signal pathway. Collectively, our work provides proof-of-principle evidence for a SeNG-mediated nano-antioxidant strategy, by which colitis could be effectively managed.

Reverse Conversion Treatment of Gaseous Sulfur Trioxide Using Metastable Sulfides from Sulfur-Rich Flue Gas

Sulfur trioxide (SO₃) is an unstable pollutant, and its removal from the gas phase of industrial flue gas remains a significant challenge. Herein, we propose a reverse conversion treatment (RCT) strategy to reduce S(VI) in SO₃ to S(IV) by combining bench-scale experiments and theoretical studies. We first demonstrated that metastable sulfides can break the S-O bond in SO₃, leading to the re-formation of sulfur dioxide (SO₂). The RCT performance varied between mono- and binary-metal sulfides, and metastable CuS had a high SO₃ conversion efficiency in the temperature range of 200-300 °C. Accordingly, the introduction of selenium (Se) lowered the electronegativity of the CuS host and enhanced its reducibility to SO₃. Among the CuSe_1-xS_x composites, CuSe_0.3S_0.7 was the optimal RCT material and reached a SO₂ yield of 6.25 mmol/g in 120 min. The low-valence state of selenium (Se^2-/Se^1-) exhibited a higher reduction activity for SO₃ than did S^2-/S^1-; however, excessive Se doping degraded the SO₃ conversion owing to the re-oxidation of SO₂ by the generated SeO₃^2-. The density functional theory calculations verified the stronger SO₃ adsorption performance (E_ads = -2.76 eV) and lower S-O bond breaking energy (E_a = 1.34 eV) over CuSe_0.3S_0.7 compared to those over CuS and CuSe. Thus, CuSe_1-xS_x can serve as a model material and the RCT strategy can make use of field temperature conditions in nonferrous smelters for SO₃ emission control.

Fluorescent hydrogels based on oxidized carboxymethyl cellulose with excellent adsorption and sensing abilities for Ag. Int J Biol Macromol 2022;213:955-966. [PMID: 35690162 DOI: 10.1016/j.ijbiomac.2022.06.029]

Heavy metal contamination in water and soil are harmful and destructive to the environment, it has always been regarded as a big problem. Herein, we developed a self-healing fluorescent hydrogel based on oxidized carboxymethyl cellulose with excellent sensing and adsorption abilities for Ag⁺. The detection and adsorption effects of hydrogels on heavy metal ions were studied. It turned out that the fluorescent hydrogel has sensitive detection and high adsorption capacity for Ag⁺, the detection limit was 3.798 μM, and the maximum adsorption capacity was 407 mg/g. The adsorption isotherm fitted the Langmuir model well, and the pseudo-secondary model for adsorption kinetics fitted well. The hydrogel could heal itself without external stimulus, it could be easily regenerated 7 times without loss of adsorption performance. In short, the prepared hydrogel has capability of self-healing, detecting and adsorbing heavy metal ions at the same time, good mechanical strength, these all made it a promising long-life adsorbent and provided a new way for wastewater treatment.

Low-Dimensional Nanomaterial Systems Formed by IVA Group Elements Allow Energy Conversion Materials to Flourish

In response to the exhaustion of traditional energy, green and efficient energy conversion has attracted growing attention. The IVA group elements, especially carbon, are widely distributed and stable in the earth’s crust, and have received a lot of attention from scientists. The low-dimensional structures composed of IVA group elements have special energy band structure and electrical properties, which allow them to show more excellent performance in the fields of energy conversion. In recent years, the diversification of synthesis and optimization of properties of IVA group elements low-dimensional nanomaterials (IVA-LD) contributed to the flourishing development of related fields. This paper reviews the properties and synthesis methods of IVA-LD for energy conversion devices, as well as their current applications in major fields such as ion battery, moisture electricity generation, and solar-driven evaporation. Finally, the prospects and challenges faced by the IVA-LD in the field of energy conversion are discussed.

Beneficial Effect of Selenium Doped Carbon Quantum Dots Supplementation on the in vitro Development Competence of Ovine Oocytes

Background

After the synthesis of selenium doped carbon quantum dots (Se/CDs) via a step-by-step hydrothermal synthesis method with diphenyl diselenide (DPDSe) as precursor, the beneficial effects of Se/CDs’ supplementation on the in vitro development competence of ovine oocytes were firstly investigated in this study by the assay of maturation rate, cortical granules’ (CGs) dynamics, mitochondrial activity, reactive oxygen species (ROS) production, epigenetic modification, transcript profile, and embryonic development competence.

Results

The results showed that the Se/CDs’ supplementation during the in vitro maturation (IVM) process not only enhanced the maturation rate, CGs’ dynamics, mitochondrial activity and embryonic developmental competence of ovine oocytes, but remarkably decreased the ROS production level of ovine oocytes. In addition, the expression levels of H3K9me3 and H3K27me3 in the ovine oocytes were significantly up-regulated after the Se/CDs’ supplementation, in consistent with the expression levels of 5mC and 5hmC. Moreover, 2994 up-regulated differentially expressed genes (DEGs) and 846 repressed DEGs were found in the oocytes after the Se/CDs’ supplementation. According to the analyses of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), these DEGs induced by the Se/CDs’ supplementation were positively related to the progesterone mediated oocyte maturation and mitochondrial functions. And these remarkably up-regulated expression levels of DEGs related to oocyte maturation, mitochondrial function, and epigenetic modification induced by the Se/CDs’ supplementation further confirmed the beneficial effect of Se/CDs’ supplementation on the in vitro development competence of ovine oocytes.

Conclusion

The Se/CDs prepared in our study significantly promoted the in vitro development competence of ovine oocytes, benefiting the extended research about the potential applications of Se/CDs in mammalian breeding technologies.