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

Eudragit S100 coated iron oxide-chitosan nanocomposites for colon targeting of 5-aminosalicylic acid ameliorate ulcerative colitis by improving intestinal barrier function and inhibiting NLRP3 inflammasome

The therapeutic effect of 5-amino salicylic acid (5-ASA), a first-line therapeutic agent for the treatment of ulcerative colitis (UC), is limited by the modest bioavailability afforded by its oral administration. In this study, a 5-ASA oral delivery system was developed using Eudragit S100-coated iron oxide-chitosan nanocomposites (ES-IOCS/5-ASA) to address this issue. According to drug release studies in vitro, ES-IOCS/5-ASA only released a small amount of drug in simulated gastric fluid with a pH of 1.2. However, in a medium with a pH of 7.5, a relatively rapid and complete release was noted. 5-ASA-loaded iron oxide-chitosan nanocomposites (IOCS/5-ASA) could be effectively taken up by NCM460 cells and performed better anti-inflammatory effects than free 5-ASA. At the same time, IOCS/5-ASA improved barrier damage in DSS-induced NCM460 cells. In vivo models of dextran sulphate sodium (DSS)-induced colitis were used to assess the therapeutic efficacy of oral administration of ES-IOCS/5-ASA. ES-IOCS/5-ASA significantly relieved DSS-induced colitis and enhanced the integrity of the intestinal epithelial barrier. ES-IOCS/5-ASA also reduced the expression of NLRP3, ASC and IL-1β. Additionally, iron oxide nanoparticles used as nanozymes could alleviate inflammation. In summary, this study indicates that ES-IOCS/5-ASA exert anti-inflammatory effects on DSS-induced colitis by improving intestinal barrier function and inhibiting NLRP3 inflammasome expression, presenting a viable therapeutic choice for the treatment of UC.

Nanozymes: Potential Therapies for Reactive Oxygen Species Overproduction and Inflammation in Ischemic Stroke and Traumatic Brain Injury

Nanozymes, which can selectively scavenge reactive oxygen species (ROS), have recently emerged as promising candidates for treating ischemic stroke and traumatic brain injury (TBI) in preclinical models. ROS overproduction during the early phase of these diseases leads to oxidative brain damage, which has been a major cause of mortality worldwide. However, the clinical application of ROS-scavenging enzymes is limited by their short in vivo half-life and inability to cross the blood-brain barrier. Nanozymes, which mimic the catalytic function of natural enzymes, have several advantages, including cost-effectiveness, high stability, and easy storage. These advantages render them superior to natural enzymes for disease diagnosis and therapeutic interventions. This review highlights recent advancements in nanozyme applications for ischemic stroke and TBI, emphasizing their potential to mitigate the detrimental effect of ROS overproduction, oxidative brain damage, inflammation, and blood-brain barrier compromise. Therefore, nanozymes represent a promising treatment modality for ROS overproduction conditions in future medical practices.

Biomimetic Integrated Nanozyme for Flare and Recurrence of Gouty Arthritis

Flare and multiple recurrences pose significant challenges in gouty arthritis. Traditional treatments provide temporary relief from inflammation but fail to promptly alleviate patient pain or effectively prevent subsequent recurrences. It should also be noted that both anti-inflammation and metabolism of uric acid are necessary for gouty arthritis, calling for therapeutic systems to achieve these two goals simultaneously. In this study, we propose a biomimetic integrated nanozyme, HMPB-Pt@MM, comprising platinum nanozyme and hollow Prussian blue. It demonstrates anti-inflammatory properties by eliminating reactive oxygen species and reducing infiltration of inflammatory macrophages. Additionally, it rapidly targets inflamed ankles through the camouflage of macrophage membranes. Furthermore, HMPB-Pt@MM exhibits urate oxidase-like capabilities, continuously metabolizing locally elevated uric acid concentrations, ultimately inhibiting multiple recurrences of gouty arthritis. In summary, HMPB-Pt@MM integrates ROS clearance with uric acid metabolism, offering a promising platform for the treatment of gouty arthritis.

Clinically Approved Ferric Maltol: A Potent Nanozyme with Added Effect for High-Efficient Catalytic Disinfection

Nanozyme has been proven to be an attractive and promising candidate to alleviate the current pressing medical problems. However, the unknown clinical safety and limited function beyond the catalysis of the most reported nanozymes cannot promise an ideal therapeutic outcome in further clinical application. Herein, we find that ferric maltol (FM), a clinically approved iron supplement synthesized through a facile scalable method, exhibits excellent peroxidase-like activity than natural horseradish peroxidase-like (HRP) and commonly reported Fe-based nanozymes, and also shows high antibacterial performance for methicillin-resistant Staphylococcus aureus (MRSA) elimination (100%) and wound disinfection. In addition, with added effects inherited from contained maltol, FM can accelerate skin barrier recovery. Therefore, the exploration of FM as a safe and desired nanozyme provides a timely alternative to current antibiotic therapy against drug-resistant bacteria.

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.

Recent Advances in Chemically Engineered Nanostructures Impact on Ischemic Stroke Treatment

Stroke is a serious public health problem that raises expenses for society and causes long-term impairment and death. However, due to restricted blood-brain barrier (BBB) penetration, there are few treatment alternatives for treating stroke. Recanalization techniques, neuroprotective medications, and recovery techniques are all forms of treatment. The ischemic stroke treatment window is too narrow for logical and efficient therapy, and detection is possible only in advanced stages. BBB integrity disruption, neurotoxicity, and the brief half-life of therapeutic thrombolytics are the key molecular pathogenic causes of ischemic stroke. Existing neuroprotective drugs' inability to promote the recovery of ischemic brain tissue after a stroke is another factor that contributes to the disease's progression, chronic nature, and severity. A possible approach to getting around these medication restrictions and boosting the effectiveness of therapies is nanotechnology. In order to get around these drug-related restrictions and boost the effectiveness of therapies for neurological conditions such as stroke, nanotechnology has emerged as a viable option. These problems might be avoided by using nanoparticle-based methods to create a thrombolytic medication that is safe to use after the tissue plasminogen activator (tPA) treatment window has passed. The idea of using biomimetic nanoparticles in the future for the treatment of ischemic stroke through immunotherapy and stem cell therapy is highlighted, along with recent advancements in the study of nanomaterials for ischemic stroke diagnostics and treatment.

Application of Nanozymes and its Progress in the Treatment of Ischemic Stroke

Nanozymes are a new kind of material which has been applied since the beginning of this century, and its birth has promoted the development of chemistry, materials science, and biology. Nanozymes can be used as a substitute for natural enzyme and has a wide range of applications; therefore, it has attracted extensive attention from all sectors of the community, and the number of studies has constantly increasing. In this paper, we introduced the outstanding achievements in the field of nanozymes in recent years from the main function, the construction of nanozyme-based biosensors, and the treatment of ischemic stroke, and we also illustrated the internal mechanism and the catalytic principle. In the end, the obstacles and challenges in the future development of nanozymes were proposed.

Antioxidant Nanozymes: Mechanisms, Activity Manipulation, and Applications

Antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase play important roles in the inhibition of oxidative-damage-related pathological diseases. However, natural antioxidant enzymes face some limitations, including low stability, high cost, and less flexibility. Recently, antioxidant nanozymes have emerged as promising materials to replace natural antioxidant enzymes for their stability, cost savings, and flexible design. The present review firstly discusses the mechanisms of antioxidant nanozymes, focusing on catalase-, superoxide dismutase-, and glutathione peroxidase-like activities. Then, we summarize the main strategies for the manipulation of antioxidant nanozymes based on their size, morphology, composition, surface modification, and modification with a metal-organic framework. Furthermore, the applications of antioxidant nanozymes in medicine and healthcare are also discussed as potential biological applications. In brief, this review provides useful information for the further development of antioxidant nanozymes, offering opportunities to improve current limitations and expand the application of antioxidant nanozymes.

Antioxidant Cascade Nanoenzyme Antagonize Inflammatory Pain by Modulating MAPK/p-65 Signaling Pathway

Chronic pain has attracted wide interest because it is a major obstacle affecting the quality of life. Consequently, safe, efficient, and low-addictive drugs are highly desirable. Nanoparticles (NPs) with robust anti-oxidative stress and anti-inflammatory properties possess therapeutic possibilities for inflammatory pain. Herein, a bioactive zeolitic imidazolate framework (ZIF)-8-capped superoxide dismutase (SOD) and Fe₃ O₄ NPs (SOD&Fe₃ O₄ @ZIF-8, SFZ) is developed to achieve enhanced catalytic, antioxidative activities, and inflammatory environment selectivity, ultimately improving analgesic efficacy. SFZ NPs reduce tert-butyl hydroperoxide (t-BOOH)-induced reactive oxygen species (ROS) overproduction, thereby depressing the oxidative stress and inhibiting the lipopolysaccharide (LPS)-induced inflammatory response in microglia. After intrathecal injection, SFZ NPs efficiently accumulate at the lumbar enlargement of the spinal cord and significantly relieve complete Freund's adjuvant (CFA)-induced inflammatory pain in mice. Moreover, the detailed mechanism of inflammatory pain therapy via SFZ NPs is further studied, where SFZ NPs inhibit the activation of the mitogen-activated protein kinase (MAPK)/p-65 signaling pathway, leading to reductions in phosphorylated protein levels (p-65, p-ERK, p-JNK, and p-p38) and inflammatory factors (tumor necrosis factor [TNF]-α, interleukin [IL]-6, and IL-1β), thereby preventing microglia and astrocyte activation for acesodyne. This study provides a new cascade nanoenzyme for antioxidant treatments and explores its potential applications as non-opioid analgesics.

Mannose-coated superparamagnetic iron oxide nanozyme for preventing postoperative cognitive dysfunction

Postoperative cognitive dysfunction (POCD) is associated with increased postoperative morbidity and mortality in patients. Excessive production of reactive oxygen species (ROS) and the consequent inflammatory response in the postoperative brain play crucial roles in the development of POCD. However, effective ways to prevent POCD have yet to be developed. Moreover, effective penetration of the blood-brain barrier (BBB) and maintaining viability in vivo are major challenges for preventing POCD using traditional ROS scavengers. Herein, mannose-coated superparamagnetic iron oxide nanoparticles (mSPIONs) were synthesized by co-precipitation method. The BBB penetration of mSPIONs was verified through fluorescent imaging and ICP-MS quantification. The ROS scavenging and anti-inflammatory of mSPIONs were evaluated in H₂O₂-treated J774A.1 ​cells and in tibial fracture mice model. The novel object recognition (NOR) and trace-fear conditioning (TFC) were used to test the cognitive function of postoperative mice. The average diameter of mSPIONs was approximately 11 ​nm. mSPIONs significantly reduced ROS levels in H₂O₂-treated cells and in hippocampus of surgical mice. mSPIONs administration reduced the levels of IL-1β and TNF-α in the hippocampus and inhibited surgery-upregulated HIF1-α/NF-κB signaling pathway. Moreover, mSPIONs significantly improved the cognitive function of postoperative mice. This study provides a new approach for preventing POCD using a nanozyme.

Harnessing nanobiotechnology for cerebral ischemic stroke management

Cerebral ischemic stroke remains one of the most serious neurological disorders that pose threats to human health, causing a large amount of long-term disability or even death throughout the world. Based on its physiologic and pathological features, there are limited available therapeutic options for effective ischemic stroke management. Encouragingly, a rapid advancement of nanobiotechnology is bringing new insights into exploring more alternative strategies against cerebral ischemic stroke, which can cleverly overcome the limitations related to conventional treatment methods. Therefore, this review focuses on the recent achievements of nanobiotechnology for ischemic stroke management, which emphasizes diverse targeted delivery strategies using various nanoplatforms including liposomes, micelles, polymeric nanoparticles, nanogels, inorganic nanomaterials, and cell-derived nano-vectors based on the pathophysiological features of ischemic stroke. Moreover, different therapeutic approaches against ischemic stroke such as neuroprotection, anti-inflammation, thrombolysis, increased blood-brain barrier penetration and reactive oxygen species scavenging are highlighted. Meanwhile, this review discusses how these versatile nanoplatforms were designed to assist in the treatment of ischemic stroke. Based on this, challenges, opportunities, and future perspectives using nanobiotechnology through rational design for effective ischemic stroke management are revealed.

The Role of Ferroptosis in Blood-Brain Barrier Injury

The blood-brain barrier (BBB) is an important barrier that maintains homeostasis within the central nervous system. Brain microvascular endothelial cells are arranged to form vessel walls and express tight junctional complexes that limit the paracellular pathways of the BBB and therefore play a crucial role in ensuring brain function. These vessel walls tightly regulate the movement of ions, molecules, and cells between the blood and the brain, which protect the neural tissue from toxins and pathogens. Primary damage caused by BBB dysfunction can disrupt the expression of tight junctions, transport proteins and leukocyte adhesion molecules, leading to brain edema, disturbances in ion homeostasis, altered signaling and immune infiltration, which can lead to neuronal cell death. Various neurological diseases are known to cause BBB dysfunction, but the mechanism that causes this disorder is not clear. Recently, ferroptosis has been found to play an important role in BBB dysfunction. Ferroptosis is a new form of regulatory cell death, which is caused by the excessive accumulation of lipid peroxides and iron-dependent reactive oxygen species. This review summarizes the role of ferroptosis in BBB dysfunction and the latest progress of ferroptosis mechanism, and further discusses the influence of various factors of ferroptosis on the severity and prognosis of BBB dysfunction, which may provide better therapeutic targets for BBB dysfunction.

Structure design mechanisms and inflammatory disease applications of nanozymes

Nanozymes are artificial enzymes with high catalytic activity, low cost, and good biocompatibility, and have received ever-increasing attention in recent years. Various inorganic and organic nanoparticles have been found to exhibit enzyme-like activities and are used as nanozymes for diverse biomedical applications ranging from tumor imaging and therapeutics to detection. However, their further clinical applications are hindered by the potential toxicity and long-term retention of nanomaterials in vivo. Clarifying the catalytic mechanism of nanozymes and identifying the key factors responsible for their behavior can guide the design of nanozyme structure, enlighten the ways to improve their enzyme-like activities, and minimize the dosage of nanozymes, leading to reduced toxicity to the human body for a real biomedical application prospect. In particular, inflammation occurring in numerous diseases is closely related to reactive oxygen species, and the active oxygen scavenging ability of nanozymes potentially exerts excellent therapeutic effects on inflammatory diseases. In this review, we systematically summarize the structure-activity relationship of nanozymes, including regulation strategies for size and morphology, surface structure, and composition. Based on the structure-activity mechanisms, a series of chemically designed nanozymes developed to target various inflammatory diseases are briefly summarized.

Newly developed gas-assisted sonodynamic therapy in cancer treatment

Sonodynamic therapy (SDT) is an emerging noninvasive treatment modality that utilizes low-frequency and low-intensity ultrasound (US) to trigger sensitizers to kill tumor cells with reactive oxygen species (ROS). Although SDT has attracted much attention for its properties including high tumor specificity and deep tissue penetration, its anticancer efficacy is still far from satisfactory. As a result, new strategies such as gas-assisted therapy have been proposed to further promote the effectiveness of SDT. In this review, the mechanisms of SDT and gas-assisted SDT are first summarized. Then, the applications of gas-assisted SDT for cancer therapy are introduced and categorized by gas types. Next, therapeutic systems for SDT that can realize real-time imaging are further presented. Finally, the challenges and perspectives of gas-assisted SDT for future clinical applications are discussed.

Nanozymes for Regenerative Medicine

Nanozymes refer to nanomaterials that catalyze enzyme substrates into products under relevant physiological conditions following enzyme kinetics. Compared to natural enzymes, nanozymes possess the characteristics of higher stability, easier preparation, and lower cost. Importantly, nanozymes possess the magnetic, fluorescent, and electrical properties of nanomaterials, making them promising replacements for natural enzymes in industrial, biological, and medical fields. On account of the rapid development of nanozymes recently, their application potentials in regeneration medicine are gradually being explored. To highlight the achievements in the regeneration medicine field, this review summarizes the catalytic mechanism of four types of representative nanozymes. Then, the strategies to improve the biocompatibility of nanozymes are discussed. Importantly, this review covers the recent advances in nanozymes in tissue regeneration medicine including wound healing, nerve defect repair, bone regeneration, and cardiovascular disease treatment. In addition, challenges and prospects of nanozyme researches in regeneration medicine are summarized.

A portable smartphone-based detection of glyphosate based on inhibiting peroxidase-like activity of heptanoic acid/Prussian blue decorated Fe3O4 nanoparticles

The rapid and onsite detection of glyphosate in tobacco products is still a great challenge. In this study, a novel smartphone-assisted sensing platform for the detection of glyphosate has been successfully proposed through the peroxidase-like activity of Fe3O4-based nanozyme. Heptanoic acid/Prussian blue (PB) decorated Fe3O4 nanoparticles (Fe3O4@C7/PB) could catalyze and oxidize 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS, colorless) into a steel blue colored product in the presence of hydrogen peroxide. Glyphosate could specifically inhibit the peroxidase-like activity of Fe3O4@C7/PB by occupying the active site, thereby the glyphosate detection could be accomplished within 10 min by monitoring the color change of ABTS. This study has developed a smartphone-based portable detection platform for online analysis of glyphosate with a detection limit of 0.1 μg mL-1. The absorbance response curve of glyphosate showed good linearity in the concentration range of 0.125-15 μg mL-1 at 415, 647, and 730 nm. Moreover, by employing a co-precipitation technology and inhibiting the peroxidase-like activity, the glyphosate analysis would be less affected by the tobacco sample matrix. The nanosensor possesses excellent selectivity and anti-interference ability, which has application value in actual samples for onsite screening.

Nanoparticles in the diagnosis and treatment of vascular aging and related diseases

Aging-induced alternations of vasculature structures, phenotypes, and functions are key in the occurrence and development of vascular aging-related diseases. Multiple molecular and cellular events, such as oxidative stress, mitochondrial dysfunction, vascular inflammation, cellular senescence, and epigenetic alterations are highly associated with vascular aging physiopathology. Advances in nanoparticles and nanotechnology, which can realize sensitive diagnostic modalities, efficient medical treatment, and better prognosis as well as less adverse effects on non-target tissues, provide an amazing window in the field of vascular aging and related diseases. Throughout this review, we presented current knowledge on classification of nanoparticles and the relationship between vascular aging and related diseases. Importantly, we comprehensively summarized the potential of nanoparticles-based diagnostic and therapeutic techniques in vascular aging and related diseases, including cardiovascular diseases, cerebrovascular diseases, as well as chronic kidney diseases, and discussed the advantages and limitations of their clinical applications.

Fe3O4 Nanozymes Improve Neuroblast Differentiation and Blood-Brain Barrier Integrity of the Hippocampal Dentate Gyrus in D-Galactose-Induced Aged Mice

Aging is a process associated with blood-brain barrier (BBB) damage and the reduction in neurogenesis, and is the greatest known risk factor for neurodegenerative disorders. However, the effects of Fe₃O₄ nanozymes on neurogenesis have rarely been studied. This study examined the effects of Fe₃O₄ nanozymes on neuronal differentiation in the dentate gyrus (DG) and BBB integrity of D-galactose-induced aged mice. Long-term treatment with Fe₃O₄ nanozymes (10 μg/mL diluted in ddH₂O daily) markedly increased the doublecortin (DCX) immunoreactivity and decreased BBB injury induced by D-galactose treatment. In addition, the decreases in the levels of antioxidant proteins including superoxide dismutase (SOD) and catalase as well as autophagy-related proteins such as Becin-1, LC3II/I, and Atg7 induced by D-galactose treatment were significantly ameliorated by Fe₃O₄ nanozymes in the DG of the mouse hippocampus. Furthermore, Fe₃O₄ nanozyme treatment showed an inhibitory effect against apoptosis in the hippocampus. In conclusion, Fe₃O₄ nanozymes can relieve neuroblast damage and promote neuroblast differentiation in the hippocampal DG by regulating oxidative stress, apoptosis, and autophagy.

Nanomaterials alleviating redox stress in neurological diseases: mechanisms and applications

Overproduced reactive oxygen and reactive nitrogen species (RONS) in the brain are involved in the pathogenesis of several neurological diseases, such as Alzheimer's disease, Parkinson's disease, traumatic brain injury, and stroke, as they attack neurons and glial cells, triggering cellular redox stress. Neutralizing RONS, and, thus, alleviating redox stress, can slow down or stop the progression of neurological diseases. Currently, an increasing number of studies are applying nanomaterials (NMs) with anti-redox activity and exploring the potential mechanisms involved in redox stress-related neurological diseases. In this review, we summarize the anti-redox mechanisms of NMs, including mimicking natural oxidoreductase activity and inhibiting RONS generation at the source. In addition, we propose several strategies to enhance the anti-redox ability of NMs and highlight the challenges that need to be resolved in their application. In-depth knowledge of the mechanisms and potential application of NMs in alleviating redox stress will help in the exploration of the therapeutic potential of anti-redox stress NMs in neurological diseases.

Nanozymes: Versatile Platforms for Cancer Diagnosis and Therapy

Natural enzymes usually suffer from high production cost, ease of denaturation and inactivation, and low yield, making them difficult to be broadly applicable. As an emerging type of artificial enzyme, nanozymes that combine the characteristics of nanomaterials and enzymes are promising alternatives. On the one hand, nanozymes have high enzyme-like catalytic activities to regulate biochemical reactions. On the other hand, nanozymes also inherit the properties of nanomaterials, which can ameliorate the shortcomings of natural enzymes and serve as versatile platforms for diverse applications. In this review, various nanozymes that mimic the catalytic activity of different enzymes are introduced. The achievements of nanozymes in different cancer diagnosis and treatment technologies are summarized by highlighting the advantages of nanozymes in these applications. Finally, future research directions in this rapidly developing field are outlooked.

Antibacterial Effect of Chitosan-Modified Fe3O4 Nanozymes on Acinetobacter baumannii

The aim of this study was to determine whether the antibacterial activity of chitosan-modified Fe₃O₄ (CS@Fe₃O₄) nanomaterials against Acinetobacter baumannii (A. baumannii) is mediated through changes in biofilm formation and reactive oxygen species (ROS) production. For this purpose, the broth dilution method was used to examine the effect of CS@Fe₃O₄ nanoparticles on bacterial growth. The effects of CS@Fe₃O₄ nanoparticles on biofilm formation were measured using a semi-quantitative crystal violet staining assay. In addition, a bacterial ROS detection kit was used to detect the production of ROS in bacteria. The results showed that CS@Fe₃O₄ nanoparticles had a significant inhibitory effect on the colony growth and biofilm formation of drug-resistant A. baumannii (p < 0.05). The ROS stress assay revealed significantly higher ROS levels in A. baumannii subjected to CS@Fe₃O₄ nanoparticle treatment than the control group (p < 0.05). Thus, we demonstrated for the first time that CS@Fe₃O₄ nanoparticles had an inhibitory effect on A. baumannii in vitro, and that the antibacterial effect of CS@Fe₃O₄ nanoparticles on drug-resistant A. baumannii was more significant than on drug-sensitive bacteria. Our findings suggest that the antibacterial mechanism of CS@Fe₃O₄ nanoparticles is mediated through inhibition of biofilm formation in drug-resistant bacteria, as well as stimulation of A. baumannii to produce ROS. In summary, our data indicate that CS@Fe₃O₄ nanoparticles could be used to treat infections caused by drug-resistant A. baumannii.

A Co-Doped Fe3O4 Nanozyme Shows Enhanced Reactive Oxygen and Nitrogen Species Scavenging Activity and Ameliorates the Deleterious Effects of Ischemic Stroke

Acute ischemic stroke has become the major cause of mortality and disability worldwide. Following ischemic stroke, the reperfusion injury is mainly mediated by the burst of reactive oxygen and nitrogen species (RONS). Therefore, blocking the excessive production or removing RONS holds great promise as a potential therapeutic strategy. Herein, we developed a Co-doped Fe3O4 nanozyme that is capable of scavenging H2O2, O2•-, •NO, and ONOO- in vitro and in vivo and provides neuroprotection against ischemic stroke. In vitro experiments showed that pre-incubation with the Co-Fe3O4 nanozyme could prevent neurotoxicity and neuroinflammation induced by H2O2 or lipopolysaccharide, respectively, in HT22 cells. After intravenous administration, the Co-Fe3O4 nanozyme showed no signs of toxicity in peripheral organs of C57BL/6J mice, even after prolonged delivery for 4 weeks. In permanent photothrombotic stroke model and transient middle cerebral artery occlusion stroke model, the Co-Fe3O4 nanozyme specifically accumulated in the infarct rim at 72 h post-stroke and was endocytosed by neurons, astrocytes, microglia, and endothelial cells. Importantly, the Co-Fe3O4 nanozyme delivery reduced the infarct volume in both stroke models. The observation that the Co-Fe3O4 nanozyme was efficacious in two well-characterized ischemic stroke models provides strong evidence that it represents a powerful tool for targeting oxidative and nitrosative stress in the ischemic brain.

Modulating poststroke inflammatory mechanisms: Novel aspects of mesenchymal stem cells, extracellular vesicles and microglia

Inflammation plays an important role in the pathological process of ischemic stroke, and systemic inflammation affects patient prognosis. As resident immune cells in the brain, microglia are significantly involved in immune defense and tissue repair under various pathological conditions, including cerebral ischemia. Although the differentiation of M1 and M2 microglia is certainly oversimplified, changing the activation state of microglia appears to be an intriguing therapeutic strategy for cerebral ischemia. Recent evidence indicates that both mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles (EVs) regulate inflammation and modify tissue repair under preclinical stroke conditions. However, the precise mechanisms of these signaling pathways, especially in the context of the mutual interaction between MSCs or MSC-derived EVs and resident microglia, have not been sufficiently unveiled. Hence, this review summarizes the state-of-the-art knowledge on MSC- and MSC-EV-mediated regulation of microglial activity under ischemic stroke conditions with respect to various signaling pathways, including cytokines, neurotrophic factors, transcription factors, and microRNAs.

Combination of cell-penetrating peptides with nanomaterials for the potential therapeutics of central nervous system disorders: a review

Although nanomedicine have greatly developed and human life span has been extended, we have witnessed the soared incidence of central nervous system (CNS) diseases including neurodegenerative diseases (Alzheimer's disease, Parkinson's disease), ischemic stroke, and brain tumors, which have severely damaged the quality of life and greatly increased the economic and social burdens. Moreover, partial small molecule drugs and almost all large molecule drugs (such as recombinant protein, therapeutic antibody, and nucleic acid) cannot cross the blood-brain barrier. Therefore, it is especially important to develop a drug delivery system that can effectively deliver therapeutic drugs to the central nervous system for the treatment of central nervous system diseases. Cell penetrating peptides (CPPs) provide a potential strategy for the transport of macromolecules through the blood-brain barrier. This study analyzed and summarized the progress of CPPs in CNS diseases from three aspects: CPPs, the conjugates of CPPs and drug, and CPPs modified nanoparticles to provide scientific basis for the application of CPPs for CNS diseases.