Crystal Facet Controlled Metal-Support Interaction in Uricase Mimics for Highly Efficient Hyperuricemia Treatment.

The effect of strong metal-support interaction (SMSI) has never been systematically studied in the field of nanozyme-based catalysis before. Herein, by coupling two different Pd crystal facets with MnO2, i.e., (100) by Pd cube (Pdc) and (111) by Pd icosahedron (Pdi), we observed the reconstruction of Pd atomic structure within the Pd-MnO2 interface, with the reconstructed Pdc (100) facet more disordered than Pdi (111), verifying the existence of SMSI in such coupled system. The rearranged Pd atoms in the interface resulted in enhanced uricase-like catalytic activity, with Pdc@MnO2 demonstrating the best catalytic performance. Theoretical calculations suggested that a more disordered Pd interface led to stronger interactions with intermediates during the uricolytic process. In vitro cell experiments and in vivo therapy results demonstrated excellent biocompatibility, therapeutic effect, and biosafety for their potential hyperuricemia treatment. Our work provides a brand-new perspective for the design of highly efficient uricase-mimic catalysts.

Manganese Amplifies Photoinduced ROS in Toluidine Blue Carbon Dots to Boost MRI Guided Chemo/Photodynamic Therapy.

The contrast agents and tumor treatments currently used in clinical practice are far from satisfactory, due to the specificity of the tumor microenvironment (TME). Identification of diagnostic and therapeutic reagents with strong contrast and therapeutic effect remains a great challenge. Herein, a novel carbon dot nanozyme (Mn-CD) is synthesized for the first time using toluidine blue (TB) and manganese as raw materials. As expected, the enhanced magnetic resonance (MR) imaging capability of Mn-CDs is realized in response to the TME (acidity and glutathione), and r1 and r2 relaxation rates are enhanced by 224% and 249%, respectively. In addition, the photostability of Mn-CDs is also improved, and show an efficient singlet oxygen (1 O2 ) yield of 1.68. Moreover, Mn-CDs can also perform high-efficiency peroxidase (POD)-like activity and catalyze hydrogen peroxide to hydroxyl radicals, which is greatly improved under the light condition. The results both in vitro and in vivo demonstrate that the Mn-CDs are able to achieve real-time MR imaging of TME responsiveness through aggregation of the enhanced permeability and retention effect at tumor sites and facilitate light-enhanced chemodynamic and photodynamic combination therapies. This work opens a new perspective in terms of the role of carbon nanomaterials in integrated diagnosis and treatment of diseases.

Breaking Osteoclast-Acid Vicious Cycle to Rescue Osteoporosis via an Acid Responsive Organic Framework-Based Neutralizing and Gene Editing Platform.

In the osteoporotic microenvironment, the acidic microenvironment generated by excessive osteoclasts not only causes irreversible bone mineral dissolution, but also promotes reactive oxygen species (ROS) production to induce osteoblast senescence and excessive receptor activator of nuclear factor kappa-B ligand (RANKL) production, which help to generate more osteoclasts. Hence, targeting the acidic microenvironment and RANKL production may break this vicious cycle to rescue osteoporosis. To achieve this, an acid-responsive and neutralizing system with high in vivo gene editing capacity is developed by loading sodium bicarbonate (NaHCO3) and RANKL-CRISPR/Cas9 (RC) plasmid in a metal-organic framework. This results showed ZIF8-NaHCO3@Cas9 (ZNC) effective neutralized acidic microenvironment and inhibited ROS production . Surprisingly, nanoparticles loaded with NaHCO3 and plasmids show higher transfection efficiency in the acidic environments as compared to the ones loaded with plasmid only. Finally, micro-CT proves complete reversal of bone volume in ovariectomized mice after ZNC injection into the bone remodeling site. Overall, the newly developed nanoparticles show strong effect in neutralizing the acidic microenvironment to achieve bone protection through promoting osteogenesis and inhibiting osteolysis in a bidirectional manner. This study provides new insights into the treatment of osteoporosis for biomedical and clinical therapies.

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.

Nanofiber-mediated sequential photothermal antibacteria and macrophage polarization for healing MRSA-infected diabetic wounds.

BACKGROUND: Diabetic wound healing remains a challenge because of its susceptibility to drug-resistant bacterial infection and its persistent proinflammatory state. Switching from proinflammatory M1 macrophages (Mφs) to proregenerative M2 dominant Mφs in a timely manner accelerates wound healing by coordinating inflammatory, proliferative, and angiogenic processes. METHODS: We propose a sequential photothermal antibacterial and subsequent M2 Mφ polarization strategy based on nanofibers (NFs) consisting of polydopamine (PDA) coating on curcumin (Cur) nanocrystals to treat Methicillin-resistant Staphylococcus aureus (MRSA)-infected diabetic wounds. RESULTS: The PDA/Cur NFs showed excellent photothermal conversion and antibacterial effects due to the PDA shell under laser irradiation, consequently resulting in the release of the inner Cur with the ability to promote cell proliferation and reinforce the M2 Mφ phenotype in vitro. In vivo studies on MRSA-infected diabetic wounds showed that PDA/Cur NFs not only inhibited MRSA infection but also accelerated the wound regeneration process. Furthermore, the NFs displayed the ability to promote the M2 Mφ phenotype with enhanced collagen deposition, angiogenesis, and cell proliferation. CONCLUSION: Overall, the NFs displayed great potential as promising therapeutics for healing infected diabetic wounds through a sequential photothermal antibacterial and M2 Mφ polarization strategy.

Bimetallic CuCo2 S4 Nanozymes with Enhanced Peroxidase Activity at Neutral pH for Combating Burn Infections.

Peroxidase-mimicking nanozymes that can generate toxic hydroxyl radicals (. OH) hold great promise as antibacterial alternatives. However, most of them display optimal performance under strongly acidic conditions (pH 3-4), and are thus not feasible for many medical uses, including burn infections with a wound pH close to neutral. Herein, we report a copper-based nanozyme (CuCo2 S4 ) that exhibits intrinsic peroxidase-like activity and can convert H2 O2 into . OH at neutral pH. In particular, bimetallic CuCo2 S4 nanoparticles (NPs) exhibited enhanced peroxidase-like activity and antibacterial capacity, superior to that of the corresponding monometallic CuS and CoS NPs. The CuCo2 S4 nanozymes possessed excellent ability to kill various bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, this CuCo2 S4 nanozymes could effectively disrupt MRSA biofilms in vitro and accelerate MRSA-infected burn healing in vivo. This work provides a new peroxidase mimic to combat bacteria in neutral pH milieu and this CuCo2 S4 nanozyme could be a promising antibacterial agent for the treatment of burn infections.

Copper/Carbon Hybrid Nanozyme: Tuning Catalytic Activity by the Copper State for Antibacterial Therapy.

Metal-carbon hybrid materials have shown promise as potential enzyme mimetics for antibacterial therapy; however, the effects of metal states and corresponding antibacterial mechanisms are largely unknown. Here, two kinds of copper/carbon nanozymes were designed, with tuned copper states from Cu0 to Cu2+. Results revealed that the copper/carbon nanozymes exhibited copper state-dependent peroxidase-, catalase-, and superoxide dismutase-like activities. Furthermore, the antibacterial activities were also primarily determined by the copper state. The different antibacterial mechanisms of these two copper/carbon nanozymes were also proposed. For the CuO-modified copper/carbon nanozymes, the released Cu2+ caused membrane damage, lipid peroxidation, and DNA degradation of Gram-negative bacteria, whereas, for Cu-modified copper/carbon nanozymes, the generation of reactive oxygen species (ROS) via peroxidase-like catalytic reactions was the determining factor against both Gram-positive and Gram-negative bacteria. Lastly, we established two bacterially infected animal models, i.e., bacteria-infected enteritis and wound healing, to confirm the antibacterial ability of the copper/carbon nanozymes. Our findings provide a deeper understanding of metal state-dependent enzyme-like and antibacterial activities and highlight a new approach for designing novel and selective antibacterial therapies based on metal-carbon nanozymes.

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.

Polystyrene microplastics arrest skeletal growth in puberty through accelerating osteoblast senescence.

Polystyrene microplastics (PS-MPs) have attracted worldwide attention to their massive accumulation in terrestrial and aquatic ecosystems. It has been demonstrated that MPs are easily to accumulate in organs and exert toxic effects. However, their exposure risk to the skeleton remains unknown. In this study, we observed PS-MPs accumulation in both the long bones and axial bones, leading to reduced body length, as well as femur and tibia length. PS-MPs treated mice exhibited redundant skeletal growth and impaired trabecular bone micro-architecture, which is due to the suppressed osteogenic ability as the number of osteoblasts decreased significantly in PS-MPs treated mice. In histological analysis, we observed the accumulation of senescent osteoblasts in the bone trabecula of PS-MPs treated mice, as well as the impaired autophagy with decreased autophagosome and reduced autophagy-related proteins in the senescent osteoblasts. Re-establishing autophagy effectively reversed the senescent phenotype in osteoblasts and ameliorated PS-MPs induced skeletal growth arrest. Hence, our study reveals the detrimental role of PS-MPs in skeletal growth in puberty through accelerating osteoblast senescence, which may be alleviated by reactivating the autophagy. This study provides new evidence of the PS-MPs on health threats and the potential therapeutic targets to reverse it.

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.

In situ formation of ferrous sulfide in glycyrrhizic acid hydrogels to promote healing of multi-drug resistant Staphylococcus aureus-infected diabetic wounds.

Diabetic wound treatment faces great challenges in clinic. Staphylococcus aureus (S. aureus) is one of the most frequently isolated pathogens from the diabetic infections, which can severely impede wound healing time. Herein, ferrous sulfide (FeS) nanoparticles were fabricated through an in situ reaction between Fe2+ and S2- in glycyrrhizic acid (GA) solution. As the FeS nanoparticles aged, the solution gradually transformed into a gel, exhibiting excellent mechanical strength, injectability, and biocompatibility as a wound dressing. In addition to its own pharmacological effects, GA could act as the protector for FeS from oxidation of air. It also provided a weak acidic microenvironment, facilitating the pH-dependent dissolution reaction of FeS to release H2S and Fe2+. Notably, the effective antibacterial performance of the FeS/GA hydrogels towards S. aureus and multi-drug resistant S. aureus (MRSA) was achieved via the degradedly released Fe2+ and H2S through combination of ferroptosis damage and energy metabolism disruption. Moreover, FeS/GA hydrogels effectively modulated the proportion of M1/M2 macrophages, reduced the secretion of inflammatory cytokines, and significantly enhanced the proliferation and migration of fibroblasts in vitro. Importantly, in an MRSA-infected diabetic wound model, the FeS/GA hydrogels efficiently eradicated bacteria and regulated the inflammatory microenvironment, thereby promoting the diabetic wound repair. Overall, our study establishes a novel strategy for developing multifunctional hydrogels that serve as an effective therapeutic platform for managing bacteria-infected diabetic wounds.

Rescuing Nucleus Pulposus Cells From Senescence via Dual-Functional Greigite Nanozyme to Alleviate Intervertebral Disc Degeneration.

High levels of reactive oxygen species (ROS) lead to progressive deterioration of mitochondrial function, resulting in tissue degeneration. In this study, ROS accumulation induced nucleus pulposus cells (NPCs) senescence is observed in degenerative human and rat intervertebral disc, suggesting senescence as a new therapeutic target to reverse intervertebral disc degeneration (IVDD). By targeting this, dual-functional greigite nanozyme is successfully constructed, which shows the ability to release abundant polysulfides and presents strong superoxide dismutase and catalase activities, both of which function to scavenge ROS and maintain the tissue at physical redox level. By significantly lowering the ROS level, greigite nanozyme rescues damaged mitochondrial function in IVDD models both in vitro and in vivo, rescues NPCs from senescence and alleviated the inflammatory response. Furthermore, RNA-sequencing reveals ROS-p53-p21 axis is responsible for cellular senescence-induced IVDD. Activation of the axis abolishes greigite nanozyme rescued NPCs senescence phenotype, as well as the alleviated inflammatory response to greigite nanozyme, which confirms the role of ROS-p53-p21 axis in greigite nanozyme's function to reverse IVDD. In conclusion, this study demonstrates that ROS-induced NPCs senescence leads to IVDD and the dual-functional greigite nanozyme holds strong potential to reverse this process, providing a novel strategy for IVDD management.

Periosteal topology creates an osteo-friendly microenvironment for progenitor cells.

The periosteum on the skeletal surface creates a unique micro-environment for cortical bone homeostasis, but how this micro-environment is formed remains a mystery. In our study, we observed the cells in the periosteum presented elongated spindle-like morphology within the aligned collagen fibers, which is in accordance with the differentiated osteoblasts lining on the cortical surface. We planted the bone marrow stromal cells(BMSCs), the regular shaped progenitor cells, on collagen-coated aligned fibers, presenting similar cell morphology as observed in the natural periosteum. The aligned collagen topology induced the elongation of BMSCs, whichfacilitated the osteogenic process. Transcriptome analysis suggested the aligned collagen induced the regular shaped cells to present part of the periosteum derived stromal cells(PDSCs) characteristics by showing close correlation of the two cell populations. In addition, the elevated expression of PDSCs markers in the cells grown on the aligned collagen-coated fibers further indicated the function of periosteal topology in manipulating cells' behavior. Enrichment analysis revealed cell-extracellular matrix interaction was the major pathway initiating this process, which created an osteo-friendly micro-environment as well. At last, we found the aligned topology of collagen induced mechano-growth factor expression as the result of Igf1 alternative splicing, guiding the progenitor cells behavior and osteogenic process in the periosteum. This study uncovers the key role of the aligned topology of collagen in the periosteum and explains the mechanism in creating the periosteal micro-environment, which gives the inspiration for artificial periosteum design.

An Inter-Supplementary Biohybrid System Based on Natural Killer Cells for the Combinational Immunotherapy and Virotherapy of Cancer.

Oncolytic adenoviruses (Ads) have gained great attention in cancer therapy because they cause direct cytolytic infection and indirectly induce antitumor immunity. However, their efficacy is compromised by host antiviral immune response, poor tumor delivery, and the immunosuppressive tumor microenvironment (TME). Here, a natural killer (NK) cell-mediated Ad delivery system (Ad@NK) is generated by harnessing the merits of the two components for combinational immunotherapy and virotherapy of cancer. In this biohybrid system, NK cells with a tumor-homing tropism act as bioreactors and shelters for the loading, protection, replication, amplification, and release of Ads, thereby leading to a highly efficient systemic tumor-targeted delivery. As feedback, Ad infection offers NK cells an enhanced antitumor immunity by activating type I interferon signaling in a STAT4-granzyme B-dependent manner. Moreover, it is found that the Ad@NK system can relieve immunosuppression in the TME by promoting the maturation of dendritic cells and the polarization of macrophages to M1 phenotype. Both in vitro and in vivo data indicate the excellent antitumor and antimetastatic functions of Ad@NKs by destroying tumor cells, inducing immunogenic cell death, and immunomodulating TME. This work provides a clinical basis for improved oncolytic virotherapy in combination with NK cell therapy based on the inter-supplementary biohybrid system.

Dietary Fe3O4 Nanozymes Prevent the Injury of Neurons and Blood-Brain Barrier Integrity from Cerebral Ischemic Stroke.

Cerebral ischemic stroke stimulates excessive reactive oxygen species, which lead to blood-brain-barrier disruption, neuron death, and aggravated cerebral infarction. Thus, it is critical to develop an antioxidant strategy for stroke treatment. Herein, we report a dietary strategy to promote stroke healing using iron oxide (Fe3O4) nanoparticles with intrinsic enzyme-like activities. We find that Fe3O4 nanozymes exhibit triple enzyme-like activities, peroxidase, catalase, and superoxide dismutase, thus potentially possessing the ability to regulate the ROS level. Importantly, intragastric administration of PEG-modified Fe3O4 nanozymes significantly reduces cerebral infarction and neuronal death in a rodent model following cerebral ischemic stroke. Ex vivo analysis shows that PEG-modified Fe3O4 nanozymes localize in the cerebral vasculature, ameliorate local redox state with decreased malondialdehyde and increased Cu/Zn SOD, and facilitate blood-brain-barrier recovery by elevating ZO-1 and Claudin-5 in the hippocampus. Altogether, our results suggest that dietary PEG-modified Fe3O4 nanozymes can facilitate blood-brain-barrier reconstruction and protect neurons following ischemic stroke.

Oral Administration of Nanoiron Sulfide Supernatant for the Treatment of Gallbladder Stones with Chronic Cholecystitis.

Cholelithiasis with chronic cholecystitis is prevalent and threatens human health. Most cholecystitis caused by bacterial infection or biofilms is accompanied by gallstones in the clinic, making gallbladder removal the only effective solution. Here, we provide a strategy to eliminate gallstone biofilms and dissolve gallstones by oral administration of a supernatant derived from nanoscale iron sulfide (nFeS supernatant). First, by using gallstones obtained from the clinic, we simulated biofilm formation on gallstones and tested the antibacterial activity of a nFeS supernatant in vitro. We found that the supernatant kills bacteria with a 5-log reduction in viability and destroys the biofilm structure. Smashed gallstones coincubated with E. coli biofilms promote gallstone formation, while nFeS supernatant can inhibit this process. Second, by using a murine (C57BL/6) model of cholelithiasis and cholecystitis, we tested the antibacterial efficacy and therapeutic effects of nFeS supernatant on cholelithiasis in vivo. Animal experimental data show that oral administration of nFeS supernatant can reduce 60% of bacteria in the gallbladder and, remarkably, remove gallstones with 2 days of treatment compared with clinical drug combinations (chenodeoxycholid acid and ciprofloxacin). Third, by performing protein abundance analysis of L02 cells and mouse livers, we observed the changes in CYP7a1, HMGCR, and SCP2 expression, indicating that the nFeS supernatant can also regulate cholesterol metabolism to prevent gallstone formation. Finally, hematologic biochemistry analysis and high-throughput sequencing technology show that the nFeS supernatant possesses high biocompatibility. Therefore, our work demonstrates that the nFeS supernatant may be a potential regimen for the treatment of cholelithiasis and cholecystitis by oral administration.

Self-Assembled Multiple-Enzyme Composites for Enhanced Synergistic Cancer Starving-Catalytic Therapy.

Inspired by the particularity of tumor microenvironments, including acidity and sensibility to reactive oxygen species (ROS), advanced and smart responsive nanomaterials have recently been developed. The present study synthesized tumor-targeted and pH-sensitive supramolecular micelles that self-assembled via host-guest recognition. The micelles consumed intratumoral glucose and lactate via loading with glucose oxidase (GOD) and lactate oxidase (LOD). Intratumoral glucose and lactate were converted into hydrogen peroxide (H2O2) and were sequentially reduced to highly toxic hydroxyl radicals (•OH) via the peroxidase (POD)-like activity of the loaded C-dot nanozymes. Tumor-killing effects were observed via cascade catalytic reactions. After an intravenous injection, the nanocomposite exhibited an excellent tumor-targeted ability with good biocompatibility, which demonstrated its effective antitumor effect. The nanocomposite effectively combined starvation and catalytic therapies and exerted a synergistic anticancer effect with minimal side effects and without external addition.

Oral biofilm elimination by combining iron-based nanozymes and hydrogen peroxide-producing bacteria.

Dental caries is a global risk in terms of oral health in many schoolchildren and in a vast majority of adults. The primary factor for caries formation is the attachment of bacteria on the tooth surface to form an oral biofilm which generates acids to demineralize calcium and eventually cause tooth decay. Oral biofilm elimination is still a challenge because bacteria are embedded inside with the biofilm matrix protecting them, preventing the penetration of antibiotics or bactericides. Promising strategies for disrupting oral biofilms have been developed, including the use of natural enzymes to degrade the biofilm matrix and hydrogen peroxide to kill bacteria. Here we demonstrate a strategy that combines nanozymes with peroxidase-like activity and bacteria generating biogenic hydrogen peroxide to eliminate oral biofilms for caries treatment. By using a saliva-coated hydroxyapatite disc and sectioned human tooth to mimic the real oral environment, we analyze the influence of iron oxide nanozymes or iron sulfide nanozymes on a Streptococcus mutans biofilm in the presence of Streptococcus gordonii which can generate hydrogen peroxide. Bacterial viability assays and biofilm morphology characterization show that the combination of nanozymes and bacteria remarkably reduces the bacteria number (5 lg reduction) and biofilm matrix (85% reduction). Therefore, the combination of iron-based nanozymes and hydrogen peroxide-generating bacteria may provide a new strategy for oral biofilm elimination in dental caries treatment.

Vitamin B2 functionalized iron oxide nanozymes for mouth ulcer healing.

Mouth ulcer is associated with inflammation and high risk of bacterial infection, which aggravates the patient's condition. Currently, there is no effective treatment for mouth ulcer. Herein, we report that vitamin-modified iron oxide nanoparticles improve the healing of mouth ulcer through anti-inflammation and antibacterial activities. We discovered that vitamin B2 (VB2) modified iron oxide nanoparticles performed enhanced peroxidase-like, catalase-like, and superoxide dismutase (SOD)-like activities, acting as typical iron oxide nanozymes (IONzymes) with triad activities. In particular, VB2 modification significantly improved the SOD-like activity, thus providing a reactive oxygen species (ROS)-scavenging ability. Cellular antioxidant experiments showed that vitamin B2 modified IONzymes (VB2-IONzymes) protect human oral keratinocytes (HOK) and BALB/3T3 cells from hydrogen peroxide (H2O2), and these cells have high biocompatibility to eukaryotic cells. In addition, VB2-IONzymes exerted an antibacterial activity against Streptococcus mutans, Staphylococcus aureus, and Escherichia coli. Importantly, VB2-IONzymes accelerated the recovery of mouth ulcer and reduced the local secretion of inflammatory factors in mouse ulcer model via ROS scavenging and antibacterial activity. Taken together, our work demonstrates that vitamin B2 modification endows iron oxide nanoparticles with enhanced enzyme-like activities and VB2-IONzymes may be a promising reagent in the treatment of mouth ulcer because of their intrinsic anti-inflammation and antibacterial capabilities.