In Situ Synthesis of Natural Antioxidase Mimics for Catalytic Anti-Inflammatory Treatments: Rheumatoid Arthritis as an Example

Regulating macrophage glucose metabolism homeostasis via mitochondrial rheostats by short fiber-microsphere scaffolds for bone repair

The alterations in glucose metabolism flux induced by mitochondrial function changes are crucial for regulating bone immune homeostasis. The restoration of mitochondrial homeostasis, serving as a pivotal rheostat for balancing glucose metabolism in immune cells, can effectively mitigate inflammation and initiate osteogenesis. Herein, an ion-activated mitochondrial rheostat fiber-microsphere polymerization system (FM@CeZnHA) was innovatively constructed. Physical-chemical and molecular biological methods confirmed that CeZnHA, characterized by a rapid degradation rate, releases Ce/Zn ions that restore mitochondrial metabolic homeostasis and M1/M2 balance of macrophages through swift redox reactions. This process reduces the glycolysis level of macrophages by down-regulating the NF-κB p65 signaling pathway, enhances their mitochondrial metabolic dependence, alleviates excessive early inflammatory responses, and promptly initiates osteogenesis. The FM network provided a stable platform for macrophage glycolytic transformation and simulated extracellular matrix microenvironment, continuously restoring mitochondrial homeostasis and accelerating ossification center formation through the release of metal ions from the internal CeZnHA for efficient bone immune cascade reactions. This strategy of bone immunity mediated by the restoration of macrophage mitochondrial metabolic function and glucose metabolic flux homeostasis opens up a new approach to treating bone defects.

End-tail soaking strategy toward robust and biomimetic sandwich-layered hydrogels for full-thickness bone regeneration

Despite an increasing number of tissue-engineered scaffolds have been developing for bone regeneration, simple and universal fabrication of biomimetic bone microstructure to repair full-thickness bone defects remains a challenge and an acute clinical demand due to the negligence of microstructural differences within the cortex of cancellous bone. In this work, a biomimetic sandwich-layered PACG-CS@Mn(III) hydrogel (SL hydrogel) was facilely fabricated in an end-tail soaking strategy by simply post-crosslinking of poly(acryloyl 2-glycine)-chitosan (PACG-CS) composite hydrogel using trivalent manganese solutions. Taking the merits of in-situ formation and flexible adjustment of chain entanglements, hydrogen bonds and metal chelate interactions, SL hydrogel with sandwich-like three-layered structures and anisotropic mechanical performance was easily customized through control of the manganese concentration and soaking time in fore-and-aft sides, simulating the structurally and mechanically biomimetic characteristics of cortical and cancellous bone. Furthermore, the produced SL hydrogel also demonstrated favorable biocompatibility and enhanced MnSOD activity via a peroxidase-like reaction, which enabled the excellent radical scavenging efficiency and anti-inflammatory regulation for facilitating the activity, proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). In vivo studies further revealed that these SL hydrogels achieved restrictive pro-vascular regeneration through their stratified structure, thereby promoting the differentiation of osteoblasts. Simultaneously, the mechanical cues of stratified structure could mediate macrophage phenotype transitions in accordance with stem cell-osteoblast differentiation process via the PI3K-AKT pathway, resulting in robust osteogenesis and high-quality bone reconstruction. This facile yet efficient strategy of turning anisotropic hydrogel offers a promising alternative for full-thickness repair of bone defects, which is also significantly imperative to achieve high-performance scaffolds with specific usage requirements and expand their clinic applicability in more complex anisotropic tissues.

In Situ Generation of Pyroptosis Inducer Mediated by Intracellular Labile Copper Pool for Safe and Robust Antitumor Immunotherapy

Pyroptosis has garnered increasing interest in the realm of cancer immunotherapy. Utilizing reactive oxygen species (ROS) to trigger oxidative stress is considered an effective strategy for promoting pyroptosis. However, existing catalytic nanoparticles used as pyroptosis inducers contain heavy metals, which inevitably cause potential side effects on normal tissues due to their high toxicity and off-target effects. Herein, a labile copper pool-mediated in situ pyroptosis inducer was designed and developed using a hydrogen-bonded organic framework (HOF)-based nanoplatform to achieve safe and robust antitumor immunotherapy. The nanoplatform could target mitochondria and elevate labile Cu2+ levels in cells, implementing the in situ synthesis of a pyroptosis inducer through the formation of catalytic nanoparticles with peroxidase (POD) and superoxide dismutase (SOD)-mimicking activities. Our results confirmed that the nanoplatform could generate high levels of ROS, resulting in pyroptotic cell death. When combined with antiprogrammed death receptor 1 therapy (αPD-1), the pyroptosis inducer exhibited excellent antitumor capacity in tumor models. Meanwhile, it exhibited minimal toxicity to healthy tissues due to the low intracellular copper concentration in normal cells. Overall, our work provides potential for the development of efficient and safe antitumor immunotherapy.

Construction of Mn2+-Polyphenol Nanoparticles and Its Application in the Treatment of Ulcerative Colitis

Ulcerative colitis (UC) is an inflammatory bowel disease characterized by chronic inflammation and ulcerative erosion of the colonic mucosa. Because of the complex causes, UC is often difficult to completely cure, greatly increasing the risk of bowel cancer and other diseases. In the UC environment, excessive production of reactive oxygen species (ROS) and high levels of inflammatory factors lead to the continuous deterioration of inflammation. We developed Mn-PEGCG nanoparticles (NPs) based on the metal-polyphenol network for the preventive treatment of UC. Mn-PEGCG NPs were synthesized by the polymerization of epigallocatechin gallate (EGCG) and further complexation with Mn2+. After oral administration, Mn-PEGCG NPs are more likely to reach the inflammation site of the colon through electrostatic interaction, effectively clear ROS, reduce the production of pro-inflammatory cytokines, exert antioxidant and anti-inflammatory effects, and protect colon cells from oxidative stress damage. In addition, it can play the role of EGCG in promoting the expression of tight junction protein and enhancing the intestinal epithelial barrier. In a mouse model of UC, oral administration of Mn-PEGCG NPs reduced intestinal inflammation, alleviated pathological structural damage in mice, and promoted mucus secretion and tight junction protein expression, thereby strengthening the intestinal barrier. Mn-PEGCG NPs can effectively alleviate inflammation and repair the intestinal barrier to maintain the stability of the intestinal environment, which is an ideal treatment strategy for UC.

Inflammation Targeting and Responsive Multifunctional Drug-Delivery Nanoplatforms for Combined Therapy of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by persistent inflammation, joint swelling, pain, and progressive joint destruction. Methotrexate (MTX) is the standard first-line treatment for RA, but its clinical application is hindered by poor water solubility and non-specific delivery. In this work, a multifunctional drug-delivery nanoplatform that targets both macrophages and tumor necrosis factor α (TNFα) is developed to enhance the therapeutic efficacy of MTX in RA. The nanoplatform consists of folic acid (FA, for macrophage targeting) and a TNFα-specific Aptamer (TNFα-Apt), facilitating a dual-targeting strategy that significantly improves the accumulation of MTX at the sites of RA lesions (≈3.5-fold). Moreover, the manganese dioxide (MnO₂) and polydopamine (PDA) coatings on the nanoplatform effectively scavenge reactive oxygen species (ROS), generate oxygen, and promote the polarization of pro-inflammatory M1 macrophages to the anti-inflammatory M2 macrophages. This shift in macrophage polarization restores the expression of key inflammatory cytokines, improving the local inflammatory microenvironment. Ultimately, the nanoplatform significantly ameliorates the inflammation and joint damage in a collagen-induced arthritis (CIA) model, suggesting that this multi-target combination therapy holds considerable potential for the treatment of RA in vivo.

Oxygen Vacancy Formation Energy Determines the Phase-Activity Relationship of MnO2 Laccase Nanozymes

Although manganese dioxide (MnO2) has been explored as a powerful laccase nanozyme for pollutant oxidation in wastewater treatment, the phase-activity relationship of multiphase MnO2 remains ambiguous and controversial. Herein, the experimental studies show that the laccase-like activities and aerobic catalytic oxidation toward tetracycline antibiotics of the six types of MnO2 are in the following order: β- > λ- > γ- > α- > ε- > δ-MnO2. Density functional theory (DFT) calculations revealed that the catalytic activities are inversely proportional to the oxygen vacancy formation energies of the different MnO2 materials. Further investigation of surface oxygen species with reactivity demonstrated that rich oxygen vacancies boost the oxygen mobility and catalytic efficiency of MnO2 nanozymes, which is in good agreement with both experimental and DFT results. Hence, this study reveals the decisive role of the crystal phase in the oxygen vacancy generation, which elucidates the laccase-like catalytic mechanism of MnO2 nanozymes and is valuable for the future design and synthesis of MnO2 nanocatalysts.

Dual-driven selenium Janus single-atom nanomotors for autonomous regulating mitochondrial oxygen imbalance to catalytic therapy of rheumatoid arthritis

O2 deficiency and excessive reactive oxygen and nitrogen species (RONS) in macrophage mitochondria is a key factor causing oxygen imbalance in rheumatoid arthritis microenvironment (RAM). Although nanocatalytic therapy that simultaneously produce O2 and eliminate RONS offer a novel strategy for RA therapy, the therapeutic efficacy of nanozymes is limited by the lack of autonomous targeting into mitochondria. Herein, we constructed a Janus-structured nanomotor (Pd@MSe) with autonomous targeting ability by embedding Pd single-atom nanozymes into mesoporous selenium (MSe) nanozymes, and obtained a composite nanomotor (Pd@MSe-TPP) with dual-driven forces by modifying with triphenylphosphine (TPP) in MSe hemisphere. In RAM, Pd@MSe-TPP nanomotor achieved autonomously target into macrophages mitochondria with the driven of generation O2 and TPP targeting effect, moreover under the single-atom effect of the Pd nanozymes enhanced electronic transfer between nanozymes, which significantly boosted GPx catalytic activity further effectively enhanced the diffusion of Pd@MSe-TPP nanomotor, thus quickly resorted the oxygen balance. Additionally, while regulating oxygen imbalance, Pd@MSe-TPP nanomotor enable rapidly blocked the inflammatory cascade, restored mitochondrial function and alleviated inflammation, further prevented cartilage degradation and effectively inhibited RA progression. Therefore, the exquisitely designed nanoplatform to regulation arthritic microenvironment provides a new direction for the RA therapy and the clinical translation of nanomedicine.

Biocatalytic cascade reactions for management of diseases

Biocatalytic cascade reactions, which evolve from the confinement of multiple enzymes within living cells, represent a promising strategy for disease management. Using tailor-made nanoplatforms, reactions induced by multiple enzymes and/or nanozymes can be precisely triggered at pathogenic sites. These promote further cascade reactions that generate therapeutic species prompting effective therapeutic outcomes with minimal side effects. Over the past few years, this approach has seen widespread applications in disease management. This review attempts to critically assess and summarize the recent advances in the use of biocatalytic cascade reactions for the management of diseases. Emphasis is placed on the design of cascade catalytic systems of high efficiency and selectivity and the implementation of specific cascade processes that respond to the endogenous substances produced in the pathological processes. The various types of biocatalytic cascade reactions are outlined according to the timeline of the catalytic steps through a series of reported examples. The challenges and outlook in the field are also discussed to encourage the further development of personalized treatments based on biocatalytic cascade reactions.

Antioxidative Aortic Aneurysm Therapy by a Mn-N4 Biomimetic Site-Engineered Nanocatalyst

Oxidative stress is a major factor in the formation of lethal aortic aneurysm. Traditional molecular antioxidants can only act as reactants to scavenge reactive oxygen species (ROS) through stoichiometric reactions, which are consumed in the process, leading to unsustainable antioxidant effects. This study proposes a nanocatalytic antioxidation strategy for treating aortic aneurysm by constructing an antioxidative biomimetic nanocatalyst, which features a Mn-N4 tetra-coordinated structure similar to natural heme catalase, providing a sustained catalytic antioxidation effect that can disproportionate H2O2 into H2O and O2. The underlying structure-function relationship and catalytic pathway of the nanocatalyst are explored, revealing a MnIII/MnV transition mechanism with inner-sphere proton-coupled two-electron transfer. Further cellular and animal investigations demonstrate that the highly antioxidatively active nanocatalyst is capable of eliminating aortal oxidative stress and aortitis to large extents, thus protecting vascular smooth muscle cells and synergistically promoting the morphological and functional recovery of aorta. This nanocatalytic antioxidation strategy holds promise for treating multiple cardiovascular diseases.

Preclinical studies of natural flavonoids in inflammatory bowel disease based on macrophages: a systematic review with meta-analysis and network pharmacology

Flavonoid is a category of bioactive polyphenolic compounds that are extensively distributed in plants with specific pharmacological properties, such as anti-inflammatory and anti-oxidant. Importantly, natural flavonoids have shown the protected function on the dextran sulfate sodium (DSS)-induced colitis in animals and lipopolysaccharides (LPS)-induced inflammatory response in macrophages. The purpose of this systematic review is to explore the efficacy of natural flavonoids in animal models of IBD (inflammatory bowel disease) and potential mechanisms in macrophages by meta-analysis and network pharmacology in preclinical studies. Relevant foundation studies were searched from January 2010 to November 2023 in databases like PubMed, Elsevier ScienceDirect, and Web of Science. Then, OriginPro software was used to extract values from images, and the analysis was performed using Review Manager 5.3. The retrieved data was analyzed according to the fixed-effects model and random-effects model. Subsequently, heterogeneity was evaluated using the I2 statistics. Lastly, network pharmacology was applied to confirm mechanisms of natural flavonoids on IBD. According to the results of meta-analysis, we found the natural flavonoids exhibited powerful therapeutic effects against IBD, which not only reversed colonic shortness (WMD = 1.33, 95% CI (1.07, 1.59), P < 0.00001), but also reduced histological score (SMD =  - 2.66, 95% CI (- 3.77, - 1.95), P < 0.00001) between natural flavonoid treatment groups compared with the experimental IBD model. Furthermore, treatment with natural flavonoids decreased the levels of tumor necrosis factor-α (TNF-α) in macrophages. Mechanistically, our summarized data substantiate that natural flavonoids alleviate LPS-induced M1 macrophage polarization, anti-oxidant, anti-inflammatory, maintain intestinal barrier, and inhibit the activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome in macrophages. Moreover, the results of network pharmacology also support this. This systematic review demonstrated the efficiency of natural flavonoids in treating IBD in preclinical research by meta-analysis and network pharmacology, which offered supporting evidence for clinical trial implementation. However, some limitations remain present, such as technique quality shortage, missed reports on account of negative results, failure to count sample size, and the risk of bias.

Nanozyme-based therapeutic strategies for rheumatoid arthritis

Rheumatoid arthritis (RA) is a prevalent chronic autoimmune disease that leads to severe joint damage and disability. Conventional treatment options are limited by their efficacy and side effect profiles. Nanozymes, nanomaterials with enzyme-like activities, offer a novel therapeutic approach for RA. This review summarizes recent advances in nanozyme-based treatments, focusing on their antioxidant and immunomodulatory roles in mitigating RA. We discuss various nanozymes, including those based on cerium, iron, manganese, silver, copper, platinum, rhodium, and multi-metallic nanozymes, which mimic natural enzymes such as superoxide dismutase, catalase, and peroxidase to reduce oxidative stress. Additionally, we explore nanozyme-based combination therapies that integrate with other strategies, such as vesicles and phototherapy, to achieve synergistic effects and enhance efficacy. This review highlights the significant potential of nanozymes in improving RA treatment, offering a new perspective for future research and clinical applications.

Photo-Triggered Fluorescence Polyelectrolyte Nanoassemblies: Manipulate and Boost Singlet Oxygen in Photodynamic Therapy

Photodynamic therapy (PDT) is a clinically approved therapeutic modality that has shown great potential for cancer treatment. However, there exist two major problems hindering PDT applications: the nonspecific phototoxicity requiring patients to stay in dark post-PDT, and the limited photodynamic efficiency. Herein, we report a photo-triggered porphyrin polyelectrolyte nanoassembling (photo-triggered PPN) strategy, in which porphyrin photosensitizer and photoswitchable energy accepter are assembled into polyelectrolyte micelles by a combined force of charge interaction and metal-ligand coordination. The polyelectrolyte-based PPN exhibits good biocompatibility, and bestows a unique "confining isolated" inner microenvironment for fully overcoming the π-π stacking of porphyrins with significant photodynamic efficiency (123-fold enhancement). Due to the high Förster resonance energy transfer (FRET) (91.5 %) between porphyrin and photoswitch in closed-form, we could use light as a specific trigger to modulate photoswitch between closed- and open-form, and manipulate the 1O2 generation in three stages: pre-PDT (quenching 1O2 generation), during PDT (activating 1O2 generation), and post-PDT (silencing 1O2 generation). This de novo strategy has for the first time realized remotely manipulating and boosting 1O2 generation in PDT, well resolving the critical and general challenges of limited photodynamic efficiency and side effects from nonspecific phototoxicity.

Antioxidative Therapy of Alcoholic Liver Injury by Amorphous Two-Dimensional Cobalt Hydroxide Nanocatalyst

The intake of excessive ethanol will activate an alternative ethanol metabolic pathway in the liver, resulting in the overproduction of reactive oxygen species (ROS), which further leads to alcoholic liver injury (ALI). Although several molecular antioxidants have been utilized in clinics for treating ALI, their efficacies are still less satisfactory. In this work, a nanocatalytic antioxidation therapeutic strategy is proposed for ALI treatment by constructing amorphous Co(OH)2 nanosheets with catalytic antioxidative property. The bis(μ-hydroxo)CoIICoII dinuclear active sites of Co(OH)2 nanosheets are capable of coordinating with hydrogen peroxide (H2O2) with significantly reduced thermodynamic barrier to form a dihydroxyl adduct bis(μ-hydroxo)CoIII(OH)CoIII(OH) favorable for catalytic H2O2 disproportionation, while amorphous and ultrathin structure further facilitates the reaction, resulting in a high catalytic efficiency (Km=59.31 mM). Thanks to the inherent hepatic passive targeting ability of nanomaterials, the antioxidative nanosheets can accumulate in liver region efficiently after intravenous administration (35.5 % ID/g accumulation efficiency), enabling efficient catalytic antioxidation in the liver to mitigate hepatic oxidative stress, protect hepatocytes from apoptosis/ferroptosis. This study provides a new methodology of nanocatalytic antioxidation for treating ALI and other hepatic diseases related to oxidative stress.

A Core-Brush Nanoplatform with Enhanced Lubrication and Anti-Inflammatory Properties for Osteoarthritis Treatment

Osteoarthritis (OA) is recognized as a highly friction-related joint disease primarily associated with increased joint friction and inflammation due to pro-inflammatory M1-type macrophage infiltration in the articular cavity. Therefore, strategies to simultaneously increase lubrication and relieve inflammation to remodel the damaged articular microenvironment are of great significance for enhancing its treatment. Herein, a multifunctional core-brush nanoplatform composed of a ROS-scavenging polydopamine-coated SiO2 core and lubrication-enhancing zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) brush and loaded with the anti-inflammatory drug curcumin by a reactive oxygen species (ROS)-liable conjugation (named as SiO2@PP-Cur) is rationally designed. Benefiting from the grafted zwitterionic PMPC brush, a tenacious hydration layer with enhanced lubricity for reducing joint abrasions is developed. More importantly, based on the mono-iodoacetic acid-induced arthritis (MIA) rat model, intra-articular injection of SiO2@PP-Cur nanoplatform can effectively alleviate articular inflammation via promoting macrophage polarization from the pro-inflammatory M1 to anti-inflammatory M2 state by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway and attenuating the degradation of cartilage matrix, resulting in the remodeling of the damaged microenvironment into a pro-regenerative microenvironment. As a result, SiO2@PP-Cur can considerably inhibit OA progression. Therefore, the work may provide a novel strategy for the development of an advanced core-brush nanoplatform for enhanced OA therapy.

Electron-donable heterojunctions with synergetic Ru-Cu pair sites for biocatalytic microenvironment modulations in inflammatory mandible defects

The clinical treatments of maxillofacial bone defects pose significant challenges due to complex microenvironments, including severe inflammation, high levels of reactive oxygen species (ROS), and potential bacterial infection. Herein, we propose the de novo design of an efficient, versatile, and precise electron-donable heterojunction with synergetic Ru-Cu pair sites (Ru-Cu/EDHJ) for superior biocatalytic regeneration of inflammatory mandible defects and pH-controlled antibacterial therapies. Our studies demonstrate that the unique structure of Ru-Cu/EDHJ enhances the electron density of Ru atoms and optimizes the binding strength of oxygen species, thus improving enzyme-like catalytic performance. Strikingly, this biocompatible Ru-Cu/EDHJ can efficiently switch between ROS scavenging in neutral media and ROS generation in acidic media, thus simultaneously exhibiting superior repair functions and bioadaptive antibacterial properties in treating mandible defects in male mice. We believe synthesizing such biocatalytic heterojunctions with exceptional enzyme-like capabilities will offer a promising pathway for engineering ROS biocatalytic materials to treat trauma, tumors, or infection-caused maxillofacial bone defects.

Multienzyme-Like Polyoxometalate-Based Single-Atom Enzymes for Cancer-Specific Therapy Through Acid-Triggered Nontoxicity-to-Toxicity Transition

Single-atom enzymes (SAzymes) exhibit great potential for chemodynamic therapy (CDT); while, general application is still challenged by their instability and unavoidable side effects during delivery. Herein, a manganese-based polyoxometalate single-atom enzyme (Mn-POM SAE) is first introduced into tumor-specific CDT, which exhibits tumor microenvironment (TME)-activated transition of nontoxicity-to-toxicity. Different from traditional POM materials, the aggregates of low-toxic Mn-POM SAE nanospheres are obtained at neutral conditions, facilitating efficient delivery and avoiding toxicity problems in normal tissues. Under acid TME conditions, these nanospheres are degraded into smaller units of toxic Mn(II)-PW11; thus, initiating cancer cell-specific therapy. The released active units of Mn(II)-PW11 exhibit excellent multienzyme-like activities (including peroxidase (POD)-like, oxidase (OXD)-like, catalase (CAT)-like, and glutathione peroxidase (Gpx)-like activities) for the synergistic cancer therapy due to the stabilized high valence Mn species (MnIII/MnIV). As demonstrated by both intracellular evaluations and in vivo experiments, ROS is generated to cause damage to lysosome membranes, further facilitating acidification and impaired autophagy to enhance cancer therapy. This study provides a detailed investigation on the acid-triggered releasing of active units and the electron transfer in multienzyme-mimic-like therapy, further enlarging the application of POMs from catalytical engineering into cancer therapy.

Selective Binding of Tannic Acid-Conjugated Lipid Nanovesicles to Proline-Rich Proteins Enhances Transdermal Lipophilic-Antioxidant Delivery

Tannic acid (TA) possesses a notable ability to adhere to proline-rich proteins that make up skin cells and the extracellular matrix (ECM) in the skin tissue. Drug carriers with this specific adhesion ability exhibit improved drug delivery efficiency on the skin. Taking advantage of this, this study presents skin-adhesive TA-conjugated lipid nanovesicles (TANVs) for enhanced transdermal antioxidant delivery. We found that TANVs exhibited selective intermolecular interactions with keratinocyte proline-rich proteins (KPRPs) and collagen that makes up skin cells by hydrogen bonding and van der Waals interactions, further enabling the strong bonding to macroscopic skin itself and ECM. We used vitamin E (α-tocopherol), which is known to effectively reduce oxidative stress but has limited skin penetration, as a drug to verify improved in vitro delivery and therapeutic efficacy. The evaluation revealed that the antioxidant-loaded TANVs exerted excellent scavenging effects against reactive oxygen species induced by ultraviolet light or peroxides in the skin, thereby enabling the development of an active drug delivery system for dermal therapy.

Scale-Up Preparation of Manganese-Iron Prussian Blue Nanozymes as Potent Oral Nanomedicines for Acute Ulcerative Colitis

Prussian blue (PB) nanozymes are demonstrated as effective therapeutics for ulcerative colitis (UC), yet an unmet practical challenge remains in the scalable production of these nanozymes and uncertainty over their efficacy. With a novel approach, a series of porous manganese-iron PB (MnPB) colloids, which are shown to be efficient scavengers for reactive oxygen species (ROS) including hydroxyl radical, superoxide anion, and hydrogen peroxide, are prepared. In vitro cellular experiments confirm the capability of the nanozyme to protect cells from ROS attack. In vivo, the administration of MnPB nanozyme through gavage at a dosage of 10 mg kg-1 per day for three doses in total potently ameliorates the pathological symptoms of acute UC in a murine model, resulting in mitigated inflammatory responses and improved viability rate. Significantly, the nanozyme produced at a large scale can be achieved at an unprecedented yield weighting ≈11 g per batch of reaction, demonstrating comparable anti-ROS activities and treatment efficacy to its small-scale counterpart. This work represents the first demonstration of the scale-up preparation of PB analog nanozymes for UC without compromising treatment efficacy, laying the foundation for further testing of these nanozymes on larger animals and promising clinical translation.

Polymerized Network-Based Artificial Peroxisome Reprogramming Macrophages for Photoacoustic Imaging-Guided Treatment of Rheumatoid Arthritis

Artificial peroxisomes (AP) with enzyme-mimetic catalytic activity and recruitment ability have drawn a great deal of attention in fabricating protocell systems for scavenging reactive oxygen species (ROS), modulating the inflammatory microenvironment, and reprogramming macrophages, which is of great potential in treating inflammatory diseases such as rheumatoid arthritis (RA). Herein, a macrophage membrane-cloaked Cu-coordinated polyphthalocyanine-based AP (CuAP) is prepared with a macrocyclic conjugated polymerized network and embedded Cu-single atomic active center, which mimics the catalytic activity and coordination environment of natural superoxide dismutase and catalase, possesses the inflammatory recruitment ability of macrophages, and performs photoacoustic imaging (PAI)-guided treatment. The results of both in vitro cellular and in vivo animal experiments demonstrated that the CuAP under ultrasound and microbubbles could efficiently scavenge excess ROS in cells and tissues, modulate microenvironmental inflammatory cytokines such as interleukin-1β, tumor necrosis factor-α, and arginase-1, and reprogram macrophages by polarization of M1 (proinflammatory phenotype) to M2 (anti-inflammatory phenotype). We believe this study offers a proof of concept for engineering multifaceted AP and a promising approach for a PAI-guided treatment platform for RA.

Critical learning from industrial catalysis for nanocatalytic medicine

Systematical and critical learning from industrial catalysis will bring inspiration for emerging nanocatalytic medicine, but the relevant knowledge is quite limited so far. In this review, we briefly summarize representative catalytic reactions and corresponding catalysts in industry, and then distinguish the similarities and differences in catalytic reactions between industrial and medical applications in support of critical learning, deep understanding, and rational designing of appropriate catalysts and catalytic reactions for various medical applications. Finally, we summarize/outlook the present and potential translation from industrial catalysis to nanocatalytic medicine. This review is expected to display a clear picture of nanocatalytic medicine evolution.

Synovium microenvironment-responsive injectable hydrogel inducing modulation of macrophages and elimination of synovial fibroblasts for enhanced treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a progressive autoimmune disease accompanied by joint swelling, cartilage erosion and bone damage. Drug therapy for RA has been restricted due to poor therapeutic effect, recurrence and adverse effects. Macrophages and synovial fibroblasts both play important roles in the pathology of RA. Macrophages secrete large amount of pro-inflammatory cytokines, while synovial fibroblasts are tightly correlated with hypoxia synovium microenvironment, cytokine release, recruitment of pro-inflammatory cells, bone and cartilage erosion. Therefore, in this timely research, an injectable and pH-sensitive peptide hydrogel loading methotrexate (MTX) and bismuthene nanosheet/polyethyleneimine (BiNS/PEI) has been developed to reduce the activity of macrophages and eliminate over-proliferated synovial fibroblasts simultaneously. MTX can reduce the cytokine secretion of macrophages/anti-apoptosis property of synovial fibroblasts and BiNS/PEI can eliminate synovial fibroblasts via photodynamic therapy (PDT) and photothermal therapy (PTT) routes. The hydrogel was injected into the acidic inflammatory synovium for precise targeting and served as a drug reservoir for pH responsive and sustained drug release, while improving the bioavailability and reducing the toxicity of MTX. Excellent therapeutic efficacy has been achieved in both in vivo and in vitro studies, and this unique drug delivery system provides a new and robust strategy to eliminate synovial fibroblasts and modulate immune system for RA treatment in clinical.

Regulation of Photophysical Behaviors in Hyperbranched Aggregation-Induced Emission Polymers for Reactive Oxygen Species Scavenging

Developing nonconjugated materials with large Stokes shifts is highly desired. In this work, three kinds of hyperbranched aggregation-induced emission (AIE) polymers with tunable n/π electronic effects were synthesized. HBPSi-CBD contains alkenyl groups in the backbone and possesses a promoted n-π* transition and red-shifted emission wavelength with a large Stokes shift of 186 nm. Experiments and theoretical simulations confirmed that the planar π electrons in the backbone are responsible for the red-shifted emission due to the strong through-space n···π interactions and restricted backbone motions. Additionally, the designed HBPSi-CBD could be utilized as an ROS scavenger after coupling with l-methionine. The HBPSi-Met exhibits remarkable ROS scavenging properties with a scavenging capacity of 77%. This work not only gains further insight into the structure-property relationship of nonconjugated hyperbranched AIE polymers but also provides a promising ROS-scavenging biomaterial for the treatment of ROS-related diseases.

Tumor-activated in situ synthesis of single-atom catalysts for O2-independent photodynamic therapy based on water-splitting

Single-atom catalysts (SACs) have attracted interest in photodynamic therapy (PDT), while they are normally limited by the side effects on normal tissues and the interference from the Tumor Microenvironment (TME). Here we show a TME-activated in situ synthesis of SACs for efficient tumor-specific water-based PDT. Upon reduction by upregulated GSH in TME, C3N4-Mn SACs are obtained in TME with Mn atomically coordinated into the cavity of C3N4 nanosheets. This in situ synthesis overcomes toxicity from random distribution and catalyst release in healthy tissues. Based on the Ligand-to-Metal charge transfer (LMCT) process, C3N4-Mn SACs exhibit enhanced absorption in the red-light region. Thereby, a water-splitting process is induced by C3N4-Mn SACs under 660 nm irradiation, which initiates the O2-independent generation of highly toxic hydroxyl radical (·OH) for cancer-specific PDT. Subsequently, the ·OH-initiated lipid peroxidation process is demonstrated to devote effective cancer cell death. The in situ synthesized SACs facilitate the precise cancer-specific conversion of inert H2O to reactive ·OH, which facilitates efficient cancer therapy in female mice. This strategy achieves efficient and precise cancer therapy, not only avoiding the side effects on normal tissues but also overcoming tumor hypoxia.

Boundary-Rich Carbon-Based Electrocatalysts with Manganese(II)-Coordinated Active Environment for Selective Synthesis of Hydrogen Peroxide

Coordinated manganese (Mn) electrocatalysts owing to their electronic structure flexibility, non-toxic and earth abundant features are promising for electrocatalytic reactions. However, achieving selective hydrogen peroxide (H2 O2 ) production through two electron oxygen reduction (2e-ORR) is a challenge on Mn-centered catalysts. Targeting this goal, we report on the creation of a secondary Mn(II)-coordinated active environment with reactant enrichment effect on boundary-rich porous carbon-based electrocatalysts, which facilitates the selective and rapid synthesis of H2 O2 through 2e-ORR. The catalysts exhibit nearly 100 % Faradaic efficiency and H2 O2 productivity up to 15.1 mol gcat -1  h-1 at 0.1 V versus reversible hydrogen electrode, representing the record high activity for Mn-based electrocatalyst in H2 O2 electrosynthesis. Mechanistic studies reveal that the epoxide and hydroxyl groups surrounding Mn(II) centers improve spin state by modifying electronic properties and charge transfer, thus tailoring the adsorption strength of *OOH intermediate. Multiscale simulations reveal that the high-curvature boundaries facilitate oxygen (O2 ) adsorption and result in local O2 enrichment due to the enhanced interaction between carbon surface and O2 . These merits together ensure the efficient formation of H2 O2 with high local concentration, which can directly boost the tandem reaction of hydrolysis of benzonitrile to benzamide with nearly 100 % conversion rate and exclusive benzamide selectivity.

Spatial engineering of single-atom Fe adjacent to Cu-assisted nanozymes for biomimetic O2 activation

The precise design of single-atom nanozymes (SAzymes) and understanding of their biocatalytic mechanisms hold great promise for developing ideal bio-enzyme substitutes. While considerable efforts have been directed towards mimicking partial bio-inspired structures, the integration of heterogeneous SAzymes configurations and homogeneous enzyme-like mechanism remains an enormous challenge. Here, we show a spatial engineering strategy to fabricate dual-sites SAzymes with atomic Fe active center and adjacent Cu sites. Compared to planar Fe-Cu dual-atomic sites, vertically stacked Fe-Cu geometry in FePc@2D-Cu-N-C possesses highly optimized scaffolds, favorable substrate affinity, and fast electron transfer. These characteristics of FePc@2D-Cu-N-C SAzyme induces biomimetic O2 activation through homogenous enzymatic pathway, resembling functional and mechanistic similarity to natural cytochrome c oxidase. Furthermore, it presents an appealing alternative of cytochrome P450 3A4 for drug metabolism and drug-drug interaction. These findings are expected to deepen the fundamental understanding of atomic-level design in next-generation bio-inspired nanozymes.

Biodegradable Metal Complex-Gated Organosilica for Dually Enhanced Chemodynamic Therapy through GSH Depletions and NIR Light-Triggered Photothermal Effects

Hollow silica spheres have been widely studied for drug delivery because of their excellent biosecurity and high porosity. However, difficulties with degradation in the tumor microenvironment (TME) and premature leaking during drug delivery limit their clinical applications. To alleviate these problems, herein, hollow organosilica spheres (HOS) were initially prepared using a "selective etching strategy" and loaded with a photothermal drug: new indocyanine green (IR820). Then, the Cu2+-tannic acid complex (Cu-TA) was deposited on the surface of the HOS, and a new nanoplatform named HOS@IR820@Cu-TA (HICT) was finally obtained. The deposition of Cu-TA can gate the pores of HOS completely to prevent the leakage of IR820 and significantly enhance the loading capacity of HOS. Once in the mildly acidic TME, the HOS and outer Cu-TA decompose quickly in response, resulting in the release of Cu2+ and IR820. The released Cu2+ can react with the endogenous glutathione (GSH) to consume it and produce Cu+, leading to the enhanced production of highly toxic ·OH through a Fenton-like reaction due to the overexpressed H2O2 in the TME. Meanwhile, the ·OH generation was remarkably enhanced by the NIR light-responsive photothermal effect of IR820. These collective properties of HICT enable it to be a smart nanomedicine for dually enhanced chemodynamic therapy through GSH depletions and NIR light-triggered photothermal effects.

Antioxidant nanozymes as next-generation therapeutics to free radical-mediated inflammatory diseases: A comprehensive review

Recent developments in exploring the biological enzyme mimicking properties in nanozymes have opened a separate avenue, which provides a suitable alternative to the natural antioxidants and enzymes. Due to high and tunable catalytic activity, low cost of synthesis, easy surface modification, and good biocompatibility, nanozymes have garnered significant research interest globally. Several inorganic nanomaterials have been investigated to exhibit catalytic activities of some of the key natural enzymes, including superoxide dismutase (SOD), catalase, glutathione peroxidase, peroxidase, and oxidase, etc. These nanozymes are used for diverse biomedical applications including therapeutics, imaging, and biosensing in various cells/tissues and animal models. In particular, inflammation-related diseases are closely associated with reactive oxygen and reactive nitrogen species, and therefore effective antioxidants could be excellent therapeutics due to their free radical scavenging ability. Although biological enzymes and other artificial antioxidants could perform well in scavenging the reactive oxygen and nitrogen species, however, suffer from several drawbacks such as the requirement of strict physiological conditions for enzymatic activity, limited stability in the environment beyond their optimum pH and temperature, and high cost of synthesis, purification, and storage make then unattractive for broad-spectrum applications. Therefore, this review systematically and comprehensively presents the free radical-mediated evolution of various inflammatory diseases (inflammatory bowel disease, mammary gland fibrosis, and inflammation, acute injury of the liver and kidney, mammary fibrosis, and cerebral ischemic stroke reperfusion) and their mitigation by various antioxidant nanozymes in the biological system. The mechanism of free radical scavenging by antioxidant nanozymes under in vitro and in vivo experimental models and catalytic efficiency comparison with corresponding natural enzymes has also been presented.

Bioactive Conjugated Polymer-Based Biodegradable 3D Bionic Scaffolds for Facilitating Bone Defect Repair

Bone defect regeneration is one of the great clinical challenges. Suitable bioactive composite scaffolds with high biocompatibility, robust new-bone formation capability and degradability are still required. This work designs and synthesizes an unprecedented bioactive conjugated polymer PT-C3 -NH2 , demonstrating low cytotoxicity, cell proliferation/migration-promoting effect, as well as inducing cell differentiation, namely regulating angiogenesis and osteogenesis to MC3T3-E1 cells. PT-C3 -NH2 is incorporated into polylactic acid-glycolic acid (PLGA) scaffolds, which is decorated with caffeic acid (CA)-modified gelatin (Gel), aiming to improve the surface water-wettability of PLGA and also facilitate to the linkage of conjugated polymer through catechol chemistry. A 3D composite scaffold PLGA@GC-PT is then generated. This scaffold demonstrates excellent bionic structures with pore size of 50-300 µm and feasible biodegradation ability. Moreover, it also exhibites robust osteogenic effect to promote osteoblast proliferation and differentiation in vitro, thus enabling the rapid regeneration of bone defects in vivo. Overall, this study provides a new bioactive factor and feasible fabrication approach of biomimetic scaffold for bone regeneration.

Silicon-containing nanomedicine and biomaterials: materials chemistry, multi-dimensional design, and biomedical application

The invention of silica-based bioactive glass in the late 1960s has sparked significant interest in exploring a wide range of silicon-containing biomaterials from the macroscale to the nanoscale. Over the past few decades, these biomaterials have been extensively explored for their potential in diverse biomedical applications, considering their remarkable bioactivity, excellent biocompatibility, facile surface functionalization, controllable synthesis, etc. However, to expedite the clinical translation and the unexpected utilization of silicon-composed nanomedicine and biomaterials, it is highly desirable to achieve a thorough comprehension of their characteristics and biological effects from an overall perspective. In this review, we provide a comprehensive discussion on the state-of-the-art progress of silicon-composed biomaterials, including their classification, characteristics, fabrication methods, and versatile biomedical applications. Additionally, we highlight the multi-dimensional design of both pure and hybrid silicon-composed nanomedicine and biomaterials and their intrinsic biological effects and interactions with biological systems. Their extensive biomedical applications span from drug delivery and bioimaging to therapeutic interventions and regenerative medicine, showcasing the significance of their rational design and fabrication to meet specific requirements and optimize their theranostic performance. Additionally, we offer insights into the future prospects and potential challenges regarding silicon-composed nanomedicine and biomaterials. By shedding light on these exciting research advances, we aspire to foster further progress in the biomedical field and drive the development of innovative silicon-composed nanomedicine and biomaterials with transformative applications in biomedicine.

Anti-Acidification and Immune Regulation by Nano-Ceria-Loaded Mg-Al Layered Double Hydroxide for Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is a chronic autoimmune disease featuring an abnormal immune microenvironment and resultant accumulation of hydrogen ions (H+ ) produced by activated osteoclasts (OCs). Currently, clinic RA therapy can hardly achieve sustained or efficient therapeutic outcomes due to the failures in generating sufficient immune modulation and manipulating the accumulation of H+ that deteriorates bone damage. Herein, a highly effective immune modulatory nanocatalytic platform, nanoceria-loaded magnesium aluminum layered double hydroxide (LDH-CeO2 ), is proposed for enhanced immune modulation based on acid neutralization and metal ion inherent bioactivity. Specifically, the mild alkaline LDH initiates significant M2 repolarization of macrophages triggered by the elevated antioxidation effect of CeO2 via neutralizing excessive H+ in RA microenvironment, thus resulting in the efficient recruitment of regulatory T cell (Treg) and suppressions on T helper 17 cell (Th 17) and plasma cells. Moreover, the osteogenic activity is stimulated by the Mg ion released from LDH, thereby promoting the damaged bone healing. The encouraging therapeutic outcomes in adjuvant-induced RA model mice demonstrate the high feasibility of such a therapeutic concept, which provides a novel and efficient RA therapeutic modality by the immune modulatory and bone-repairing effects of inorganic nanocatalytic material.

A novel highly thermostable and stress resistant ROS scavenging metalloprotein from Paenibacillus

Reactive oxygen species (ROS) are unstable metabolites produced during cellular respiration that can cause extensive damage to the body. Here we report a unique structural metalloprotein called RSAPp for the first time, which exhibits robust ROS-scavenging activity, high thermostability, and stress resistance. RSAPp is a previously uncharacterized DUF2935 (domain of unknown function, accession number: cl12705) family protein from Paenibacillus, containing a highly conserved four-helix bundle with binding sites for variable-valence metal ions (Mn2+/Fe2+/Zn2+). Enzymatic characterization results indicated that RSAPp displays the functionality of three different antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). In particular, RSAPp exhibits a significant SOD-like activity that is remarkably effective in eliminating superoxide radicals (up to kcat/KM = 2.27 × 1011 mol-1 s-1), and maintains the catalytical active in a wide range of temperatures (25-100 °C) and pH (pH 2.0-9.0), as well as resistant to high temperature, alkali and acidic pH, and 55 different concentrations of detergent agents, chemical solvents, and inhibitors. These properties make RSAPp an attractive candidate for various industrial applications, including cosmetics, food, and pharmaceuticals.

Deep Insight of Design, Mechanism, and Cancer Theranostic Strategy of Nanozymes

Since the discovery of enzyme-like activity of Fe3O4 nanoparticles in 2007, nanozymes are becoming the promising substitutes for natural enzymes due to their advantages of high catalytic activity, low cost, mild reaction conditions, good stability, and suitable for large-scale production. Recently, with the cross fusion of nanomedicine and nanocatalysis, nanozyme-based theranostic strategies attract great attention, since the enzymatic reactions can be triggered in the tumor microenvironment to achieve good curative effect with substrate specificity and low side effects. Thus, various nanozymes have been developed and used for tumor therapy. In this review, more than 270 research articles are discussed systematically to present progress in the past five years. First, the discovery and development of nanozymes are summarized. Second, classification and catalytic mechanism of nanozymes are discussed. Third, activity prediction and rational design of nanozymes are focused by highlighting the methods of density functional theory, machine learning, biomimetic and chemical design. Then, synergistic theranostic strategy of nanozymes are introduced. Finally, current challenges and future prospects of nanozymes used for tumor theranostic are outlined, including selectivity, biosafety, repeatability and stability, in-depth catalytic mechanism, predicting and evaluating activities.

Multiple therapeutic mechanisms of pyrrolic N-rich g-C3N4 nanosheets with enzyme-like function in the tumor microenvironment

Nanozyme-based synergistic catalytic therapies for tumors have attracted extensive research attention. However, the unsatisfactory efficiency and negative impact of the tumor microenvironment (TME) hinder its clinical applications. In this study, we provide an easy method to prepare transition metals loaded onto pyrrolic nitrogen-rich g-C3N4 (PN-g-C3N4) for forming metal-N4 sites. This N-rich material effectively transfers electrons from g-C3N4 to metal-N4 sites, promotes the oxidation-reduction reaction of metals with different valence states, and improves material reusability. Under TME conditions, copper ions loaded onto PN-g-C3N4 (Cu-PN-g-C3N4, CPC) can produce ·OH through a Fenton-like reaction for tumor inhibition. This Fenton-like reaction and tumor cell inhibition can be improved further by a photodynamic effect caused by light irradiation. We introduced upconversion nanoparticles (UCNPs) into CPC to obtain nano-enzymes (UCNPs@Cu-PN-g-C3N4, UCPC) for effectively penetrating the tissue, which emits light corresponding to the UV absorption region of CPC when excited with 980 nm near-infrared (NIR) light. The nanoplatform can reduce H2O2 concentration upon exposure to NIR light; this induces an increase in dissolved oxygen content and produces a higher supply of reactive oxygen species (ROS) for destroying tumor cells. Owing to the narrow bandgap (1.92 eV) of UCPC under 980 light irradiation, even under the condition of hypoxia, the excited electrons in the conduction band can reduce insoluble O2 through a single electron transfer process, thus effectively generating O2•-. Nanoenzyme materials with catalase properties produce three types of ROS (·OH, O2•- and 1O2) when realizing chemodynamic and photodynamic therapies. An excellent therapeutic effect was established by killing cells in vitro and the tumor-inhibiting effect in vivo, proving that the prepared nanoenzymes have an effective therapeutic effect and that the endogenous synergistic treatment of multiple treatment technologies can be realized.

Metal ions: the unfading stars of bone regeneration-from bone metabolism regulation to biomaterial applications

In recent years, bone regeneration has emerged as a remarkable field that offers promising guidance for treating bone-related diseases, such as bone defects, bone infections, and osteosarcoma. Among various bone regeneration approaches, the metal ion-based strategy has surfaced as a prospective candidate approach owing to the extensive regulatory role of metal ions in bone metabolism and the diversity of corresponding delivery strategies. Various metal ions can promote bone regeneration through three primary strategies: balancing the effects of osteoblasts and osteoclasts, regulating the immune microenvironment, and promoting bone angiogenesis. In the meantime, the complex molecular mechanisms behind these strategies are being consistently explored. Moreover, the accelerated development of biomaterials broadens the prospect of metal ions applied to bone regeneration. This review highlights the potential of metal ions for bone regeneration and their underlying mechanisms. We propose that future investigations focus on refining the clinical utilization of metal ions using both mechanistic inquiry and materials engineering to bolster the clinical effectiveness of metal ion-based approaches for bone regeneration.

Multifunctional nanozyme-reinforced copper-coordination polymer nanoparticles for drug-resistance bacteria extinction and diabetic wound healing

BACKGROUND

Drug-resistant bacterial infections in chronic wounds are a persistent issue, as they are resistant to antibiotics and can cause excessive inflammation due to generation of reactive oxygen species (ROS). An effective solution would be to not only combat bacterial infections but also scavenge ROS to relieve inflammation at the wound site. Scaffolds with antioxidant properties are attractive for their ability to scavenge ROS, and there is medical demand in developing antioxidant enzyme-mimicking nanomaterials for wound healing.

METHODS

In this study, we fabricated copper-coordination polymer nanoparticles (Cu-CPNs) through a self-assembly process. Furthermore, ε-polylysine (EPL), an antibacterial and cationic polymer, was integrated into the Cu-CPNs structure through a simple one-pot self-assembly process without sacrificing the glutathione peroxidase (GPx) and superoxide dismutase (SOD)-mimicking activity of Cu-CPNs.

RESULTS

The resulting Cu-CPNs exhibit excellent antioxidant propertiesin mimicking the activity of glutathione peroxidase and superoxide dismutase and allowing them to effectively scavenge harmful ROS produced in wound sites. The in vitro experiments showed that the resulting Cu-CPNs@EPL complex have superior antioxidant properties and antibacterial effects. Bacterial metabolic analysis revealed that the complex mainly affects the cell membrane integrity and nucleic acid synthesis that leads to bacterial death.

CONCLUSIONS

The Cu-CPNs@EPL complex has impressive antioxidant properties and antibacterial effects, making it a promising solution for treating drug-resistant bacterial infections in chronic wounds. The complex's ability to neutralize multiple ROS and reduce ROS-induced inflammation can help relieve inflammation at the wound site. Schematic illustration of the ROS scavenging and bacteriostatic function induced by Cu-CPNs@EPL nanozyme in the treatment of MRSA-infected wounds.

Ferrihydrite Nanoparticles Alleviate Rheumatoid Arthritis by Nanocatalytic Antioxidation and Oxygenation

Oxidative stress and hypoxia are two key biochemical factors in the development of rheumatoid arthritis (RA). As both reactive oxygen species (ROS) and oxygen gas (O2) are oxygen-related chemicals, we suggest that a redox reaction converting ROS into O2 can mitigate oxidative stress and hypoxia concurrently, synergistically modulating the inflammatory microenvironment. In this work, ferrihydrite, a typical iron oxyhydroxide, is prepared in nanodimensions in which tetrahedrally coordinated Fe can form a composite catalytic center by coupling with an adjacent hydroxyl group, cooperatively facilitating H2O2 decomposition and O2 generation, presenting a high catalase-like activity. In the RA region, the nanomaterial catalyzes the conversion of excess H2O2 into O2, achieving both antioxidation and oxygenation favoring the alleviation of inflammation. Both cellular and in vivo experiments demonstrate the desirable efficacy of ferrihydrite nanoparticles for RA treatment. This work provides a methodology for the catalytic therapy of inflammatory diseases featuring both oxidative stress and hypoxia.

Ca-DEX biomineralization-inducing nuts reverse oxidative stress and bone loss in rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease, and the inflammatory response during its development can lead to joint cartilage and bone damage up to disability. Dexamethasone (DEX) can effectively alleviate the inflammatory response in RA, but the severe adverse effects that occur after its long-term administration limit its clinical development. Herein, we propose a Ca-DEX biomineralization-inducing nut (CaCO3-DEX) with controlled release properties for mitigating the toxic side effects of DEX in RA treatment, especially the damage to cartilage and bone. CaCO3-DEX releases the drug and Ca2+ preferentially in an inflammatory environment. Both in vitro and in vivo studies demonstrate that CaCO3-DEX significantly reduces the secretion of pro-inflammatory factors and inhibits ROS production in vitro, as well as demonstrates superior pro-biomineralization and osteogenic differentiation potential. In the collagen-induced rheumatoid arthritis model (CIA model), CaCO3-DEX significantly reduces the clinical score of arthritis in mice, and the imaging results show a noticeable relief of edema and bone erosion in CIA model mice treated with CaCO3-DEX, while inflammatory factors at the injury areas are significantly reduced, which provides favorable protection to cartilage and bone.

Bio-responsive and multi-modality imaging nanomedicine for osteoarthritis theranostics

Osteoarthritis (OA) is one of the most common joint diseases currently, characterized by the gradual degradation of cartilage, remodeling of subchondral bone, development of synovitis, degenerative alterations in the menisci, and formation of osteophytes. Generally, loss of articular cartilage is the most common pathological manifestation of OA. However, owing to the lack of blood vessels and nerves, the damaged cartilage is unable to execute self-repair. Therefore, early detection and treatment of cartilage lesions are extremely vital. Given that precise diagnosis and therapeutic strategy are indispensable from the basic pathological features of OA, an ideal therapeutic strategy should cater to the specific features of the OA microenvironment to achieve disease-modifying therapy. To date, nanomedicine presents an opportunity to achieve the precisely targeted delivery of agents and stimuli-sensitive release at the optimum dose, which may be coupled with a controlled release profile and reduced side effects. This review mainly summarizes inherent and microenvironment traits of OA and outlines stimuli-responsive nanotherapies, including internal bio-responsive (e.g., reactive oxygen species, pH, and protease) and external (e.g., photo stimuli, temperature, ultrasound, and magnetic field) responsive nanotherapies. Furthermore, multi-targeted therapeutic strategies combined with multi-modality imaging are also discussed. In general, future exploration of more novel stimuli-responsive nanotherapies that can be used for early diagnosis and cartilage targeting may help ameliorate OA-related cartilage damage, decrease pain, and promote joint function.

Macrophage Reprogramming via Targeted ROS Scavenging and COX-2 Downregulation for Alleviating Inflammation

Inflammation-related diseases affect large populations of people in the world and cause substantial healthcare burdens, which results in significant costs in time, material, and labor. Preventing or relieving uncontrolled inflammation is critical for the treatment of these diseases. Herein, we report a new strategy for alleviating inflammation by macrophage reprogramming via targeted reactive oxygen species (ROS) scavenging and cyclooxygenase-2 (COX-2) downregulation. As a proof of concept, we synthesize a multifunctional compound named MCI containing a mannose-based macrophage targeting moiety, an indomethacin (IMC)-based segment for inhibiting COX-2, and a caffeic acid (CAF)-based section for ROS clearance. As revealed by a series of in vitro experiments, MCI could significantly attenuate the expression of COX-2 and the level of ROS, leading to M1 to M2 macrophage reprogramming, as evidenced by the reduction and the elevation in the levels of pro-inflammatory M1 markers and anti-inflammatory M2 markers, respectively. Furthermore, in vivo experiments show MCI's promising therapeutic effects on rheumatoid arthritis (RA). Our work illustrates the success of targeted macrophage reprogramming for inflammation alleviation, which sheds light on the development of new anti-inflammatory drugs.

Manganese-Based Antioxidase-Inspired Biocatalysts with Axial Mn-N5 Sites and 2D d-π-Conjugated Networks for Rescuing Stem Cell Fate

Constructing highly effective biocatalysts with controllable coordination geometry for eliminating reactive oxygen species (ROS) to address the current bottlenecks in stem-cell-based therapeutics remains challenging. Herein, inspired by the coordination structure of manganese-based antioxidase, we report a manganese-coordinated polyphthalocyanine-based biocatalyst (Mn-PcBC) with axial Mn-N5 sites and 2D d-π-conjugated networks that serves as an artificial antioxidase to rescue stem cell fate. Owing to the unique chemical and electronic structures, Mn-PcBC displays efficient, multifaceted, and robust ROS-scavenging activities, including elimination of H2 O2 and O2 ⋅- . Consequently, Mn-PcBC efficiently rescues the bioactivity and functionality of stem cells in high-ROS-level microenvironments by protecting the transcription of osteogenesis-related genes. This study offers essential insight into the crucial functions of axially coordinated Mn-N5 sites in ROS scavenging and suggests new strategies to create efficient artificial antioxidases for stem-cell therapies.

Multifunctional Janus Nanoplatform for Efficiently Synergistic Theranostics of Rheumatoid Arthritis

Progress has been made in the application of nanomedicine in rheumatoid arthritis (RA) treatment. However, the whole process of monitoring and treatment of RA remains a formidable challenge due to the complexity of the chronic autoimmune disease. In this study, we develop a Janus nanoplatform (denoted as Janus-CPS) composed of CeO₂-Pt nanozyme subunit on one side and periodic mesoporous organosilica (PMO) subunit on another side for simultaneous early diagnosis and synergistic therapy of RA. The Janus nanostructure, which enables more active sites to be exposed, enhances the reactive oxygen species scavenging capability of CeO₂-Pt nanozyme subunit as compared to their core-shell counterpart. Furthermore, micheliolide (MCL), an extracted compound from natural plants with anti-osteoclastogenesis effects, is loaded into the mesopores of PMO subunit to synergize with the anti-inflammation effect of nanozymes for efficient RA treatment, which has been demonstrated by in vitro cellular experiments and in vivo collagen-induced arthritis (CIA) model. In addition, by taking advantage of the second near-infrared window (NIR-II) fluorescent imaging, indocyanine green (ICG)-loaded Janus-CPS exhibits desirable effectiveness in detecting RA lesions at a very early stage. It is anticipated that such a Janus nanoplatform may offer an alternative strategy of functional integration for versatile theranostics.

Electron transfer-based antioxidant nanozymes: Emerging therapeutics for inflammatory diseases

Inflammatory diseases are usually featured with relatively high level of reactive oxygen species (ROS). The excess ROS facilitate the polarization of microphages into proinflammatory M1 phenotype, and cause DNA damage, protein carbonylation, and lipid peroxidation, resulting in further deterioration of inflammatory diseases. Therefore, alleviating oxidative stress by ROS scavenging has been an effective strategy for reversing inflammation. Inspired by the natural antioxidant enzymes, electron transfer-based artificial antioxidant nanozymes have been emerging therapeutics for the treatment of inflammatory diseases. The present review starts with the basic knowledge of ROS and diseases, followed by summarizing the possible active centers for the preparation of antioxidant nanozymes. The strategies for the design of antioxidant nanozymes on the purpose of higher catalytic activity are provided, and the applications of the developed antioxidant nanozymes on the therapy of inflammatory diseases are discussed. A perspective is included for the design and applications of artificial antioxidant nanozymes in biomedicine as well.

Multifunctional Nanoplatform for Mild Microwave-Enhanced Thermal, Antioxidative, and Chemotherapeutic Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is usually associated with excessive proliferation of M1-type proinflammatory macrophages, resulting in severe hypoxia and excess reactive oxygen species (ROS) in the joint cavity. Inhibiting M1-type proinflammatory macrophages and/or repolarizing them into M2 phenotype anti-inflammatory cells by alleviating hypoxia and scavenging ROS could be a promising strategy for RA treatment. In this work, a microwave-sensitive metal-organic framework of UiO-66-NH₂ is constructed for coating a nanoenzyme of cerium oxide (CeO₂) and loading with the drug celastrol (Cel) to give UiO-66-NH₂/CeO₂/Cel, which is ultimately wrapped with hyaluronic acid (HA) to form a nanocomposite UiO-66-NH₂/CeO₂/Cel@HA (UCCH). With the microwave-susceptible properties of UiO-66-NH₂, the thermal effect of microwaves can eliminate the excessive proliferation of inflammatory cells. In addition, superoxide-like and catalase-like activities originating from CeO₂ in UCCH are boosted to scavenge ROS and accelerate the decomposition of H₂O₂ to produce O₂ under microwave irradiation. The nonthermal effect of microwaves could synergistically promote the repolarization of M1-type macrophages into the M2 phenotype. Accompanied by the release of the anti-RA chemotherapeutic drug Cel, UCCH can efficiently ameliorate RA in vitro and in vivo through microwave-enhanced multisynergistic effects. This strategy could inspire the design of other multisynergistic platforms enhanced by microwaves to exploit new treatment modalities in RA therapies.

Glucose Oxidase-Integrated Metal-Polyphenolic Network as a Microenvironment-Activated Cascade Nanozyme for Hyperglycemic Wound Disinfection

The high systemic blood glucose concentration of hyperglycemic wound microenvironment (WME) severely impedes the disinfection and healing of infected skin wounds. Herein, a WME-activated smart natural product, integrated GOx-GA-Fe nanozyme (GGFzyme), is engineered, which combines a nanozyme and natural enzyme to promote reactive oxygen species (ROS) generation in situ for hyperglycemic wound disinfection. GGFzyme can consume a high concentration of glucose in hyperglycemia wounds and generate H₂O₂. The conversion of glucose into gluconic acid not avails starvation treatment but reduces the pH of WME to elevate the catalytic activities of both the nanozyme (GA-Fe) and natural enzyme (GOx). And H₂O₂ is then high efficiently catalyzed into ^•OH and O₂^•- in situ to combat pathogenic bacteria and promote wound disinfection. The high catalytic antibacterial capacity and superior biosafety, combined with beneficial WME modulation, demonstrate that GGFzyme is a promising therapeutic agent for hyperglycemic wounds.

ROS generation strategy based on biomimetic nanosheets by self-assembly of nanozymes

Reactive oxygen species (ROS) play an important role in physiology and have been applied in tumor therapy. However, insufficient endogenous H₂O₂ and hypoxia in cancer cells can lead to limited ROS production and poor therapeutic efficacy. Herein, we develop a biomimetic nanosheet material based on the self-assembly of nanozymes that could supply H₂O₂ under acidic conditions and catalyze a cascade of intracellular biochemical reactions to produce ROS under both normoxic and hypoxic conditions without any external stimuli. In this system, the copper peroxide nanosheets (CPNS), which are pH-responsive, were prepared through coordination of H₂O₂ to Cu²⁺ and then modified using ultrafine Pt NPs to form CPNS@Pt. The CPNS could decompose under acidic conditions, allowing the simultaneous release of Fenton catalytic Cu²⁺ and H₂O₂ accompanied by a Fenton-type reaction between them. On the other hand, Pt NPs were also released. The released Pt NPs behave as an oxidase mimic and catalase mimic. In this way, the well-defined CPNS@Pt can not only relieve hypoxic conditions but also generate ROS to induce cell apoptosis, thereby paving the way for the development of a nanozyme with multienzyme activity as a therapeutic strategy.

Combining Cobalt Ferrite Nanozymes with a Natural Enzyme to Reshape the Tumor Microenvironment for Boosted Cascade Enzyme-Like Activities

Nanozymes with the merits of effective enzyme-mimic activities, tunable catalytic properties, pH/temperature tolerance, and high stability have been consumingly researched for nanocatalytic therapy. Herein, the union nanozymes and a natural enzyme nanoplatform (DMSN@CoFe₂O₄/GOD-PCM) are elaborately designed by simply depositing an ultrasmall cobalt ferrite (CoFe₂O₄) bimetallic oxide nanozyme and natural glucose oxidase (GOD) that are loaded into the aperture (∼12 nm) of dendritic mesoporous silica (DMSN) for near-infrared-II-enhanced tumor therapy. Upon irradiation, the hyperthermia generated by CoFe₂O₄ nanozymes unlocks the "gate" of phase-change material (PCM) for releasing GOD, which reshapes the specific tumor microenvironment (TME) through the glucose metabolism pathway. The resulting strengthened acid condition and a considerable amount of H₂O₂ efficiently initiate the cascade catalysis reactions. Moreover, highly toxic hydroxyl radicals are generated with a Co/Fe dual-cycle system of ultrasmall CoFe₂O₄ nanozymes. The in situ glutathione consumption and hypoxia relief further amplify oxidative stress. In addition, chemotherapeutic effects due to the cytotoxicity of cobalt ions enhance the therapeutic performance. Collectively, this study provides a proof of concept for TME-reshaped natural and artificial nanozyme cascade catalysis for combined reactive oxygen species-based therapy and chemotherapy.

Nano-Based Co-Delivery System for Treatment of Rheumatoid Arthritis

A systemic autoimmune condition known as rheumatoid arthritis (RA) has a significant impact on patients’ quality of life. Given the complexity of RA’s biology, no single treatment can totally block the disease’s progression. The combined use of co-delivery regimens integrating various diverse mechanisms has been widely acknowledged as a way to make up for the drawbacks of single therapy. These days, co-delivery systems have been frequently utilized for co-treatment, getting over drug limitations, imaging of inflammatory areas, and inducing reactions. Various small molecules, nucleic acid drugs, and enzyme-like agents intended for co-delivery are frequently capable of producing the ability to require positive outcomes. In addition, the excellent response effect of phototherapeutic agents has led to their frequent use for delivery together with chemotherapeutics. In this review, we discuss different types of nano-based co-delivery systems and their advantages, limitations, and future directions. In addition, we review the prospects and predicted challenges for the combining of phototherapeutic agents with conventional drugs, hoping to provide some theoretical support for future in-depth studies of nano-based co-delivery systems and phototherapeutic agents.