Polydopamine nanoparticles for the treatment of acute inflammation-induced injury

Carboxymethyl cellulose/quaternized chitosan hydrogel loaded with polydopamine nanoparticles promotes spinal cord injury recovery by anti-ferroptosis and M1/M2 polarization modulation

Spinal cord injury (SCI) represents a catastrophic neurological condition resulting in long-term loss of motor, autonomic, and sensory functions. Recently, ferroptosis, an iron-regulated form of cell death distinct from apoptosis, has emerged as a potential therapeutic target for SCI. In this study, we developed an injectable hydrogel composed of carboxymethyl cellulose (CMC), and quaternized chitosan (QCS), loaded with modified polydopamine nanoparticles (PDA NPs), referred to as CQP hydrogel. This hydrogel effectively scavenged reactive oxygen species (ROS), prevented the accumulation of Fe2+ and lipid peroxidation associated with ferroptosis, and restored mitochondrial functions in primary neuronal cells. When administered to animal models (rats) with SCI, the CQP hydrogels improved motor function by regulating iron homeostasis, inhibiting ferroptosis, and mitigating oxidative stress injury. Both in vitro and in vivo studies corroborated the capacity of CQP hydrogels to promote the shift from M1 to M2 polarization of microglia/macrophages. These findings suggest that CQP hydrogels, functioning as a localized iron-chelating system, have potential as biomaterials to enhance recovery from SCI by targeting ferroptosis and modulating anti-inflammatory macrophages activity.

Erythrocyte-Like Mesoporous PDA@CeO2 Nanozyme with Dual Drugs for Periodontitis Treatment

Periodontitis is a chronic oral inflammatory disease with the characteristic of excess oxidative stress in the inflammatory site, dramatically decreasing the quality of life. Studies show that nanozymes can be ideal candidates for ROS scavenging in periodontitis. Here, we design a multipath anti-inflammatory mesoporous polydopamine@cerium oxide nanobowl (mPDA@CeO2 NB) with multienzyme mimicking properties, which combines the advantages of both CeO2 NP and mPDA NB for synergistically eliminating reactive oxygen species (ROS), including hydroxyl radical (•OH), hydrogen peroxide (H2O2), and superoxide (O2•-). Besides, the erythrocyte-like structure of mNBs makes them a facility for cell uptake, and the mesopores can load both hydrophobic and hydrophilic drugs for combined anti-inflammatory therapy. In vitro and in vivo experiments prove that the combination of CeO2 and mPDA can synergistically achieve multiple complementary ROS eliminations and suppression of ROS-induced inflammation. Moreover, the ROS regulation plus anti-inflammatory drugs in one mPDA@CeO2 NB prevents the progression of periodontitis in a mouse model. Therefore, the design of mPDA@CeO2 NB with these excellent properties provides a therapeutic strategy for inflammatory diseases.

Emerging application of nanomedicine-based therapy in acute respiratory distress syndrome

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are serious lung injuries caused by various factors, leading to increased permeability of the alveolar-capillary barrier, reduced stability of the alveoli, inflammatory response, and hypoxemia. Despite several decades of research since ARDS was first formally described in 1967, reliable clinical treatment options are still lacking. Currently, supportive therapy and mechanical ventilation are prioritized, and there is no medication that can be completely effective in clinical treatment. In recent years, nanomedicine has developed rapidly and has exciting preclinical treatment capabilities. Using a drug delivery system based on nanobiotechnology, local drugs can be continuously released in lung tissue at therapeutic levels, reducing the frequency of administration and improving patient compliance. Furthermore, this novel drug delivery system can target specific sites and reduce systemic side effects. Currently, many nanomedicine treatment options for ARDS have demonstrated efficacy. This review briefly introduces the pathophysiology of ARDS, discusses various research progress on using nanomedicine to treat ARDS, and anticipates future developments in related fields.

Intra-Articular Injection of PLGA/Polydopamine Core-Shell Nanoparticle Attenuates Osteoarthritis Progression

Osteoarthritis (OA) is a common joint disease characterized by progressive cartilage degeneration. Unfortunately, currently available clinical drugs are mainly analgesics and cannot alleviate the development of OA. Kartogenin (KGN) has been found to promote the differentiation of bone marrow mesenchymal stem cells (BMSCs) into chondrocytes for the treatment of cartilage damage in early OA. However, KGN, as a small hydrophobic molecule, is rapidly cleared from the synovial fluid after intra-articular injection. This study synthesized a KGN-loaded nanocarrier based on PLGA/polydopamine core/shell structure to treat OA. The fluorescence signal of KGN@PLGA/PDA-PEG-E7 nanoparticles lasted for 4 weeks, ensuring long-term sustained release of KGN from a single intra-articular injection. In addition, the polyphenolic structure of PDA enables it to effectively scavenge reactive oxygen species, and the BMSC-targeting peptide E7 (EPLQLKM) endows KGN@PLGA/PDA-PEG-E7 NPs with an effective affinity for BMSCs. As a result, the KGN@PLGA/PDA-PEG-E7 nanoparticles could effectively induce cartilage in vitro and protect the cartilage and subchondral bone in a rat ACLT model. This therapeutic strategy could also be extended to the delivery of other drugs, targeting other tissues to treat joint diseases.

Targeted delivery of NO donor and ROS scavenger for synergistic treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is characterized by high level of reactive oxygen species (ROS) and proinflammatory cytokines, which facilitate the activation of the inflammatory signaling such as NF-κB pathway and exacerbate the development of inflammation. Herein, we designed a nanodrug by encapsulating the NO donor S-nitrosoglutathione (GSNO) into an emulsion and coating the surface with a polydopamine (PDA) layer to yield GSNO@PDA, which simultaneously scavenged the extra ROS and suppressed NF-κB signaling for potent RA treatment. To enhance the cellular uptake and NO generation efficiency, dextran sulfate (DS) and Cu2+ were anchored on the surface of GSNO@PDA to obtain the final formulation GSNO@PDA@DS. Our results demonstrated that GSNO@PDA@DS were successfully prepared and the modification of DS effectively boosted the cellular uptake of GSNO@PDA@DS. Moreover, GSNO@PDA@DS lowered cellular ROS and elevated intracellular NO, resulting in a decrease of M1 phenotype, inhibition of NF-κB pathway and down-regulation of proinflammatory cytokine tumor necrosis factor-α (TNF-α). Further in vivo studies confirmed that GSNO@PDA@DS significantly relieved symptoms and bone erosion by regulating the microenvironment of RA, highlighting the potential of GSNO@PDA@DS for RA therapy through ROS scavenging and NO-mediated suppression of inflammatory signaling.

Mucoadhesive, antioxidant, and lubricant catechol-functionalized poly(phosphobetaine) as biomaterial nanotherapeutics for treating ocular dryness

Dry eye disease (DED) is associated with ocular hyperosmolarity and inflammation. The marketed topical eye drops for DED treatment often lack bioavailability and precorneal residence time. In this study, we investigated catechol-functionalized polyzwitterion p(MPC-co-DMA), composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) and dopamine methacrylamide (DMA) monomers, as potential topical nanotherapeutics for DED. The copolymers were synthesized via random free-radical copolymerization, producing different proportions of catecholic functionalization. All as-prepared polymer compositions displayed good ocular biocompatibility. At a feeding ratio of 1:1, p(MPC1-co-DMA1) can facilitate a robust mucoadhesion via Michael addition and/or Schiff base reaction, thus prolonging ocular residence time after 4 days of topical instillation. The hydration lubrication of MPC and radical-scavenging DMA endow the nano-agent to ease tear-film hyperosmolarity and corneal inflammation. A single dose of p(MPC1-co-DMA1) (1 mg/mL) after 4 days post-instillation can protect the cornea against reactive oxygen species, inhibiting cell apoptosis and the over-expression of pro-inflammatory factors (IL-6 and TNF-α). In clinical assessment, DED-induced rabbit eyes receiving p(MPC1-co-DMA1) could increase lacrimal fluid secretion by 5-fold higher than cyclosporine A. The catechol-functionalized polyzwitterion with enhanced lubricity, mucoadhesion, and anti-oxidation/anti-inflammation properties has shown high promise as a bioactive eye drop formulation for treating DED.

Ferrocene-functionalized polydopamine film timely mediates M1-to-M2 macrophage polarization through adaptive wettability

Dynamical control of macrophage polarization from M1 (pro-inflammatory) to M2 (anti-inflammatory) at implant surfaces is essential for balancing innate immunity and tissue repair. In this aspect, the design of orthopedic implant that can response to inflammation microenvironment with transformation in surface properties has shown promising in timely driving M1-to-M2 macrophage transition. Considering excessive reactive oxygen species (ROS) contribute to macrophage M1 polarization and progression of inflammation, in this study, ferrocene modified polydopamine (PDA-Fc) films were deposited on plasma sprayed Ti coatings to endow the implants with ROS-responsive and -scavenging abilities. Plasma sprayed Ti (PST) coating and PDA modified PST coating (PST/PDA) served as control. The presence of PDA endowed PST/PDA and PST/PDA-Fc with free-radical scavenging abilities. Moreover, PST/PDA-Fc showed adaptive wettability as evidenced by increased hydrophilicity under H2O2 treatment. With respect to PST/PDA, PST/PDA-Fc exerted greater effects on inducing lipopolysaccharides-induced M1 macrophages to adopt M2-type macrophage phenotype, characterized by higher percentage of CD206-positive cells, increased cell elongation rate and higher expression level of anti-inflammatory cytokine arginase type 1. The results obtained in our study may provide a prospective approach for manipulating an appropriate immune response at implant surfaces.

Advancements in Regenerative Hydrogels in Skin Wound Treatment: A Comprehensive Review

This state-of-the-art review explores the emerging field of regenerative hydrogels and their profound impact on the treatment of skin wounds. Regenerative hydrogels, composed mainly of water-absorbing polymers, have garnered attention in wound healing, particularly for skin wounds. Their unique properties make them well suited for tissue regeneration. Notable benefits include excellent water retention, creating a crucially moist wound environment for optimal healing, and facilitating cell migration, and proliferation. Biocompatibility is a key feature, minimizing adverse reactions and promoting the natural healing process. Acting as a supportive scaffold for cell growth, hydrogels mimic the extracellular matrix, aiding the attachment and proliferation of cells like fibroblasts and keratinocytes. Engineered for controlled drug release, hydrogels enhance wound healing by promoting angiogenesis, reducing inflammation, and preventing infection. The demonstrated acceleration of the wound healing process, particularly beneficial for chronic or impaired healing wounds, adds to their appeal. Easy application and conformity to various wound shapes make hydrogels practical, including in irregular or challenging areas. Scar minimization through tissue regeneration is crucial, especially in cosmetic and functional regions. Hydrogels contribute to pain management by creating a protective barrier, reducing friction, and fostering a soothing environment. Some hydrogels, with inherent antimicrobial properties, aid in infection prevention, which is a crucial aspect of successful wound healing. Their flexibility and ability to conform to wound contours ensure optimal tissue contact, enhancing overall treatment effectiveness. In summary, regenerative hydrogels present a promising approach for improving skin wound healing outcomes across diverse clinical scenarios. This review provides a comprehensive analysis of the benefits, mechanisms, and challenges associated with the use of regenerative hydrogels in the treatment of skin wounds. In this review, the authors likely delve into the application of rational design principles to enhance the efficacy and performance of hydrogels in promoting wound healing. Through an exploration of various methodologies and approaches, this paper is poised to highlight how these principles have been instrumental in refining the design of hydrogels, potentially revolutionizing their therapeutic potential in addressing skin wounds. By synthesizing current knowledge and highlighting potential avenues for future research, this review aims to contribute to the advancement of regenerative medicine and ultimately improve clinical outcomes for patients with skin wounds.

Injectable, Antioxidative, and Tissue-Adhesive Nanocomposite Hydrogel as a Potential Treatment for Inner Retina Injuries

Reactive oxygen species (ROS) have been recognized as prevalent contributors to the development of inner retinal injuries including optic neuropathies such as glaucoma, non-arteritic anterior ischemic optic neuropathy, traumatic optic neuropathy, and Leber hereditary optic neuropathy, among others. This underscores the pivotal significance of oxidative stress in the damage inflicted upon retinal tissue. To combat ROS-related challenges, this study focuses on creating an injectable and tissue-adhesive hydrogel with tailored antioxidant properties for retinal applications. GelCA, a gelatin-modified hydrogel with photo-crosslinkable and injectable properties, is developed. To enhance its antioxidant capabilities, curcumin-loaded polydopamine nanoparticles (Cur@PDA NPs) are incorporated into the GelCA matrix, resulting in a multifunctional nanocomposite hydrogel referred to as Cur@PDA@GelCA. This hydrogel exhibits excellent biocompatibility in both in vitro and in vivo assessments, along with enhanced tissue adhesion facilitated by NPs in an in vivo model. Importantly, Cur@PDA@GelCA demonstrates the potential to mitigate oxidative stress when administered via intravitreal injection in retinal injury models such as the optic nerve crush model. These findings underscore its promise in advancing retinal tissue engineering and providing an innovative strategy for acute neuroprotection in the context of inner retinal injuries.

ROS scavenging activity of polydopamine nanoparticle-loaded supramolecular gelatin-based hydrogel promoted cardiomyocyte proliferation

Reactive oxygen species (ROS) play essential roles in cellular functions, but maintaining ROS balance is crucial for effective therapeutic interventions, especially during cell therapy. In this study, we synthesized an injectable gelatin-based hydrogel, in which polydopamine nanoparticles were entrapped using supramolecular interactions. The surfaces of the nanoparticles were modified using adamantane, enabling their interactions with β-cyclodextrin-conjugated with gelatin. We evaluated the cytotoxicity and antioxidant properties of the hydrogel on neonatal rat cardiomyocytes (NRCM), where it demonstrated the ability to increase the metabolic activity of NRCMs exposed to hydrogen peroxide (H2O2) after 5 days. Hydrogel-entrapped nanoparticle exhibited a high scavenging capability against hydroxyl radical, 1'-diphenyl-2-picrylhydrazyl radicals, and H2O2, surpassing the effectiveness of ascorbic acid solution. Notably, the presence of polydopamine nanoparticles within the hydrogel promoted the proliferation activity of NRCMs, even in the absence of excessive ROS due to H2O2 treatment. Additionally, when the hydrogel with nanoparticles was injected into an air pouch model, it reduced inflammation and infiltration of immune cells. Notably, the levels of anti-inflammatory factors, IL-10 and IL-4, were significantly increased, while the pro-inflammatory factor TNF-α was suppressed. Therefore, this novel ROS-scavenging hydrogel holds promise for both efficient cell delivery into inflamed tissue and promoting tissue repair.

Synergistic chemotherapy/PTT/oxygen enrichment by multifunctional liposomal polydopamine nanoparticles for rheumatoid arthritis treatment

Amultifunctional liposomal polydopamine nanoparticle (MPM@Lipo) was designed in this study, to combine chemotherapy, photothermal therapy (PTT) and oxygen enrichment to clear hyperproliferating inflammatory cells and improve the hypoxic microenvironment for rheumatoid arthritis (RA) treatment. MPM@Lipo significantly scavenged intracellular reactive oxygen species and relieved joint hypoxia, thus contributing to the repolarization of M1 macrophages into M2 phenotype. Furthermore, MPM@Lipo could accumulate at inflammatory joints, inhibit the production of inflammatory factors, and protect cartilage in vivo, effectively alleviating RA progression in a rat adjuvant-induced arthritis model. Moreover, upon laser irradiation, MPM@Lipo can elevate the temperature to not only significantly obliterate excessively proliferating inflammatory cells but also accelerate the production of methotrexate and oxygen, resulting in excellent RA treatment effects. Overall, the use of synergistic chemotherapy/PTT/oxygen enrichment therapy to treat RA is a powerful potential strategy.

High altitude hypoxia and oxidative stress: The new hope brought by free radical scavengers

Various strategies can be employed to prevent and manage altitude illnesses, including habituation, oxygenation, nutritional support, and medication. Nevertheless, the utilization of drugs for the prevention and treatment of hypoxia is accompanied by certain adverse effects. Consequently, the quest for medications that exhibit minimal side effects while demonstrating high efficacy remains a prominent area of research. In this context, it is noteworthy that free radical scavengers exhibit remarkable anti-hypoxia activity. These scavengers effectively eliminate excessive free radicals and mitigate the production of reactive oxygen species (ROS), thereby safeguarding the body against oxidative damage induced by plateau hypoxia. In this review, we aim to elucidate the pathogenesis of plateau diseases that are triggered by hypoxia-induced oxidative stress at high altitudes. Additionally, we present a range of free radical scavengers as potential therapeutic and preventive approaches to mitigate the occurrence of common diseases associated with hypoxia at high altitudes.

Manganese-Based Immunomodulatory Nanocomposite with Catalase-Like Activity and Microwave-Enhanced ROS Elimination Ability for Efficient Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is a chronic autoimmune disease commonly associated with the accumulation of hyperactive immune cells (HICs), particularly macrophages of pro-inflammatory (M1) phenotype, accompanied by the elevated level of reactive oxygen species (ROS), decreased pH and O2 content in joint synovium. In this work, an immunomodulatory nanosystem (IMN) is developed for RA therapy by modulating and restoring the function of HICs in inflamed tissues. Manganese tetraoxide nanoparticles (Mn3 O4 ) nanoparticles anchored on UiO-66-NH2 are designed, and then the hybrid is coated with Mn-EGCG film, further wrapped with HA to obtain the final nanocomposite of UiO-66-NH2 @Mn3 O4 /Mn-EGCG@HA (termed as UMnEH). When UMnEH diffuses to the inflammatory site of RA synovium, the stimulation of microwave (MW) irradiation and low pH trigger the slow dissociation of Mn-EGCG film. Then the endogenously overexpressed hydrogen peroxide (H2 O2 ) disintegrates the exposed Mn3 O4 NPs to promote ROS scavenging and O2 generation. Assisted by MW irradiation, the elevated O2 content in the RA microenvironment down-regulates the expression of hypoxia-inducible factor-1α (HIF-1α). Coupled with the clearance of ROS, it promotes the re-polarization of M1 phenotype macrophages into anti-inflammatory (M2) phenotype macrophages. Therefore, the multifunctional UMnEH nanoplatform, as the IMN, exhibits a promising potential to modulate and restore the function of HICs and has an exciting prospect in the treatment of RA.

Engineered nanodrug targeting oxidative stress for treatment of acute kidney injury

Acute kidney injury (AKI) is a clinical syndrome characterized by a rapid decline in renal function, and is associated with a high risk of death. Many pathological changes happen in the process of AKI, including crucial alterations to oxidative stress levels. Numerous efforts have thus been made to develop effective medicines to scavenge excess reactive oxygen species (ROS). However, researchers have encountered several significant challenges, including unspecific biodistribution, high biotoxicity, and in vivo instability. To address these problems, engineered nanoparticles have been developed to target oxidative stress and treat AKI. This review thoroughly discusses the methods that empower nanodrugs to specifically target the glomerular filtration barrier and presents the latest achievements in engineering novel ROS-scavenging nanodrugs in clustered sections. The analysis of each study's breakthroughs and imperfections visualizes the progress made in developing effective nanodrugs with specific biodistribution and oxidative stress-targeting capabilities. This review fills the blank of a comprehensive outline over current progress in applying nanotechnology to treat AKI, providing potential insights for further research.

Melanin/melanin-like nanoparticles: As a naturally active platform for imaging-guided disease therapy

The development of biocompatible and efficient nanoplatforms that combine diagnostic and therapeutic functions is of great importance for precise disease treatment. Melanin, an endogenous biopolymer present in living organisms, has attracted increasing attention as a versatile bioinspired functional platform owing to its unique physicochemical properties (e.g., high biocompatibility, strong chelation of metal ions, broadband light absorption, high drug binding properties) and inherent antioxidant, photoprotective, anti-inflammatory, and anti-tumor effects. In this review, the fundamental physicochemical properties and preparation methods of natural melanin and melanin-like nanoparticles were outlined. A systematical description of the recent progress of melanin and melanin-like nanoparticles in single, dual-, and tri-multimodal imaging-guided the visual administration and treatment of osteoarthritis, acute liver injury, acute kidney injury, acute lung injury, brain injury, periodontitis, iron overload, etc. Was then given. Finally, it concluded with a reasoned discussion of current challenges toward clinical translation and future striving directions. Therefore, this comprehensive review provides insight into the current status of melanin and melanin-like nanoparticles research and is expected to optimize the design of novel melanin-based therapeutic platforms and further clinical translation.

Metronidazole-loaded polydopamine nanomedicine with antioxidant and antibacterial bioactivity for periodontitis

Aim: This study focused on treating periodontitis with bacterial infection and local over accumulation of reactive oxygen species. Materials & methods: Polydopamine nanoparticles (PDA NPs) were exploited as efficient carriers for encapsulated metronidazole (MNZ). The therapeutic efficacy and biocompatibility of PDA@MNZ NPs were investigated through both in vitro and in vivo studies. Results: The nanodrug PDA@MNZ NPs were successfully fabricated, with well-defined physicochemical characteristics. In vitro, the PDA@MNZ NPs effectively eliminated intracellular reactive oxygen species and inhibited the growth of Porphyromonas gingivalis. Moreover, the PDA@MNZ NPs exhibited synergistic therapy for periodontitisin in vivo. Conclusion: PDA@MNZ NPs were confirmed with exceptional antimicrobial and antioxidant functions, offering a promising avenue for synergistic therapy in periodontitis.

Reactive oxygen species (ROS) scavenging biomaterials for anti-inflammatory diseases: from mechanism to therapy

Inflammation is a fundamental defensive response to harmful stimuli, but the overactivation of inflammatory responses is associated with most human diseases. Reactive oxygen species (ROS) are a class of chemicals that are generated after the incomplete reduction of molecular oxygen. At moderate levels, ROS function as critical signaling molecules in the modulation of various physiological functions, including inflammatory responses. However, at excessive levels, ROS exert toxic effects and directly oxidize biological macromolecules, such as proteins, nucleic acids and lipids, further exacerbating the development of inflammatory responses and causing various inflammatory diseases. Therefore, designing and manufacturing biomaterials that scavenge ROS has emerged an important approach for restoring ROS homeostasis, limiting inflammatory responses and protecting the host against damage. This review systematically outlines the dynamic balance of ROS production and clearance under physiological conditions. We focus on the mechanisms by which ROS regulate cell signaling proteins and how these cell signaling proteins further affect inflammation. Furthermore, we discuss the use of potential and currently available-biomaterials that scavenge ROS, including agents that were engineered to reduce ROS levels by blocking ROS generation, directly chemically reacting with ROS, or catalytically accelerating ROS clearance, in the treatment of inflammatory diseases. Finally, we evaluate the challenges and prospects for the controlled production and material design of ROS scavenging biomaterials.

Self-driven immune checkpoint blockade and spatiotemporal-sensitive immune response monitoring in acute myeloid leukemia using an all-in-one turn-on bionanoprobe

Immune checkpoint (ICP) blockade (ICB) is one of the most promising immunotherapies for acute myeloid leukemia (AML). However, owing to their heterogeneity, AML cells may cause uncoordinated metabolic fluxes and heterogeneous immune responses, inducing the release of a spatiotemporally sensitive immune response marker. Timely and in situ detection of immune responses in ICB therapy is important for therapeutic strategy adjustment. Herein, we constructed an all-in-one nanoprobe for self-driving ICB and simultaneously detecting an immune response in the same AML cell in vivo, thus enabling accurate evaluation of heterogenetic immune responses in living AML mice without additional drug treatment or probe processes. The nature-inspire polydopamine (PDA) nanoparticles loaded with an ICP blocker were targeted to the leukocyte immunoglobulin like receptor B4 (a new ICP) of AML cells to induce the release of immune response marker granzyme B (GrB). The PDA nanoparticles were additionally paired with carbon-derived graphene quantum dots (GQDs) to construct a full-organic 'turn-on' bionanoprobe that can transfer fluorescence resonance energy for GrB detection. This multifunctional nanoprobe was validated for triggering ICB therapy and monitoring the changes of GrB levels in real-time both in vitro and in vivo. The organic nanoprobe showed excellent permeability and retention in tumor cells and high biocompatibility in vivo. This bionanoprobe orderly interacted with the upstream ICP molecules and downstream signal molecule GrB, thereby achieving in situ immune response signals within the therapeutic efficacy evaluation window.

Topical application of synthetic melanin promotes tissue repair

In acute skin injury, healing is impaired by the excessive release of reactive oxygen species (ROS). Melanin, an efficient scavenger of radical species in the skin, performs a key role in ROS scavenging in response to UV radiation and is upregulated in response to toxic insult. In a chemical injury model in mice, we demonstrate that the topical application of synthetic melanin particles (SMPs) significantly decreases edema, reduces eschar detachment time, and increases the rate of wound area reduction compared to vehicle controls. Furthermore, these results were replicated in a UV-injury model. Immune array analysis shows downregulated gene expression in apoptotic and inflammatory signaling pathways consistent with histological reduction in apoptosis. Mechanistically, synthetic melanin intervention increases superoxide dismutase (SOD) activity, decreases Mmp9 expression, and suppresses ERK1/2 phosphorylation. Furthermore, we observed that the application of SMPs caused increased populations of anti-inflammatory immune cells to accumulate in the skin, mirroring their decrease from splenic populations. To enhance antioxidant capacity, an engineered biomimetic High Surface Area SMP was deployed, exhibiting increased wound healing efficiency. Finally, in human skin explants, SMP intervention significantly decreased the damage caused by chemical injury. Therefore, SMPs are promising and effective candidates as topical therapies for accelerated wound healing, including via pathways validated in human skin.

Laser-Induced Graphitization of Polydopamine on Titania Nanotubes

Since the discovery of laser-induced graphite/graphene, there has been a notable surge of scientific interest in advancing diverse methodologies for their synthesis and applications. This study focuses on the utilization of a pulsed Nd:YAG laser to achieve graphitization of polydopamine (PDA) deposited on the surface of titania nanotubes. The partial graphitization is corroborated through Raman and XPS spectroscopies and supported by water contact angle, nanomechanical, and electrochemical measurements. Reactive molecular dynamics simulations confirm the possibility of graphitization in the nanosecond time scale with the evolution of NH3, H2O, and CO2 gases. A thorough exploration of the lasing parameter space (wavelength, pulse energy, and number of pulses) was conducted with the aim of improving either electrochemical activity or photocurrent generation. Whereas the 532 nm laser pulses interacted mostly with the PDA coating, the 365 nm pulses were absorbed by both PDA and the substrate nanotubes, leading to a higher graphitization degree. The majority of the photocurrent and quantum efficiency enhancement is observed in the visible light between 400 and 550 nm. The proposed composite is applied as a photoelectrochemical (PEC) sensor of serotonin in nanomolar concentrations. Because of the suppressed recombination and facilitated charge transfer caused by the laser graphitization, the proposed composite exhibits significantly enhanced PEC performance. In the sensing application, it showed superior sensitivity and a limit of detection competitive with nonprecious metal materials.

Cryptotanshinone-Doped Photothermal Synergistic MXene@PDA Nanosheets with Antibacterial and Anti-Inflammatory Properties for Wound Healing

Humans are threatened by bacteria and other microorganisms, resulting in countless pathogen-related infections and illnesses. Accumulation of reactive oxygen species (ROS) in infected wounds activates strong inflammatory responses. The overuse of antibiotics has led to increasing bacterial resistance. Therefore, effective ROS scavenging and bactericidal capacity are essential and the advanced development of collaborative therapeutic techniques to combat bacterial infections is needed. Here, this work developes an MXene@polydopamine-cryptotanshinone (MXene@PDA-CPT) antibacterial nanosystem with excellent reactive oxygen and nitrogen species scavenging ability, which effectively inactivates drug-resistant bacteria and biofilms, thereby promoting wound healing. In this system, the adhesion of polydopamine nanoparticles to MXene produced a photothermal synergistic effect and free radical scavenging activity, presenting a promising antibacterial and anti-inflammatory strategy. This nanosystem causes fatal damage to bacterial membranes. The loading of cryptotanshinone further expanded the advantages of the system, causing a stronger bacterial killing effect and inflammation mitigatory effect with desired biosafety and biocompatibility. In addition, combining nanomaterials and active ingredients of traditional Chinese medicine, this work provides a new rationale for the future development of wound dressings, which contributes to eliminating bacterial resistance, delaying disease deterioration, and alleviating the pain of patients.

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

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

Bioinspired polydopamine nanoparticles as efficient antioxidative and anti-inflammatory enhancers against UV-induced skin damage

Excessive and prolonged ultraviolet radiation (UVR) exposure causes photodamage, photoaging, and photocarcinogenesis in human skin. Therefore, safe and effective sun protection is one of the most fundamental requirements. Living organisms tend to evolve various natural photoprotective mechanisms to avoid photodamage. Among them, melanin is the main functional component of the photoprotective system of human skin. Polydopamine (PDA) is synthesized as a mimic of natural melanin, however, its photoprotective efficiency and mechanism in protecting against skin damage and photoaging remain unclear. In this study, the novel sunscreen products based on melanin-inspired PDA nanoparticles (NPs) are rationally designed and prepared. We validate that PDA NPs sunscreen exhibits superior effects on photoprotection, which is achieved by the obstruction of epidermal hyperplasia, protection of the skin barrier, and resolution of inflammation. In addition, we find that PDA NPs are efficiently intake by keratinocytes, exhibiting robust ROS scavenging and DNA protection ability with minimal cytotoxicity. Intriguingly, PDA sunscreen has an influence on maintaining homeostasis of the dermis, displaying an anti-photoaging property. Taken together, the biocompatibility and full photoprotective properties of PDA sunscreen display superior performance to those of commercial sunscreen. This work provides new insights into the development of a melanin-mimicking material for sunscreens.

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.

Double-network hydrogel enhanced by SS31-loaded mesoporous polydopamine nanoparticles: Symphonic collaboration of near-infrared photothermal antibacterial effect and mitochondrial maintenance for full-thickness wound healing in diabetes mellitus

Diabetic wound healing has become a serious healthcare challenge. The high-glucose environment leads to persistent bacterial infection and mitochondrial dysfunction, resulting in chronic inflammation, abnormal vascular function, and tissue necrosis. To solve these issues, we developed a double-network hydrogel, constructed with pluronic F127 diacrylate (F127DA) and hyaluronic acid methacrylate (HAMA), and enhanced by SS31-loaded mesoporous polydopamine nanoparticles (MPDA NPs). As components, SS31, a mitochondria-targeted peptide, maintains mitochondrial function, reduces mitochondrial reactive oxygen species (ROS) and thus regulates macrophage polarization, as well as promoting cell proliferation and migration, while MPDA NPs not only scavenge ROS and exert an anti-bacterial effect by photothermal treatment under near-infrared light irradiation, but also control release of SS31 in response to ROS. This F127DA/HAMA-MPDA@SS31 (FH-M@S) hydrogel has characteristics of adhesion, superior biocompatibility and mechanical properties which can adapt to irregular wounds at different body sites and provide sustained release of MPDA@SS31 (M@S) NPs. In addition, in a diabetic rat full thickness skin defect model, the FH-M@S hydrogel promoted macrophage M2 polarization, collagen deposition, neovascularization and wound healing. Therefore, the FH-M@S hydrogel exhibits promising therapeutic potential for skin regeneration.

Melanin biopolymers from microbial world with future perspectives-a review

Melanin is an amorphous polymer made of heterogeneous functional groups synthesized by diverse organisms including fungi, bacteria, animals, and plants. It was widely acknowledged for its biological processes and its key role in the protection of organisms from environmental stress. Recently, melanin clutches attention in the field of nanobiotechnology, drug delivery, organic semiconductors and bioelectronics, environmental bioremediation, photoprotection, etc., Furthermore, melanin from natural sources like microbial community shows antimicrobial, fighting cancer, radical scavenging, cosmeceuticals, and many therapeutic areas as well. Though the multipotentiality nature of melanin has been put forth, real-world applications still flag fall behind, which might be anticipated to the inadequate and high price essence of natural melanin. However, current bioprocess technologies have paved for the large-scale or industrial production of microbial melanin, which could help in the replacement of synthetic melanin. Thus, this review emphasizes the various sources for melanin, i.e., types-based on its pathways and its chemical structures, functional efficiency, physical properties, and conventional and modern methods of both extraction and characterization. Moreover, an outlook on how it works in the field of medicine, bioremediation, and other related areas provides perspectives on the complete exploitation of melanin in practical applications of medicine and the environment.

Hollow-polydopamine-nanocarrier-based near-infrared-light/pH-responsive drug delivery system for diffuse alveolar hemorrhage treatment

Introduction: Diffuse alveolar hemorrhage (DAH) is a serious complication caused by systemic lupus erythematosus (SLE). Tissue damage and changes in immune response are all associated with excessive free radical production. Therefore, removing excess reactive oxygen species are considered a feasible scheme for diffuse alveolar hemorrhage treatment. Cyclophosphamide is often used as the main therapeutic drug in clinics. However, CTX carries a high risk of dose-increasing toxicity, treatment intolerance, and high recurrence rate. The combination of therapeutic drugs and functional nanocarriers may provide an effective solution. PDA is rich in phenolic groups, which can remove the reactive oxygen species generated in inflammatory reactions, and can serve as excellent free radical scavengers. Methods: We developed a hollow polydopamine (HPDA) nanocarrier loaded with CTX by ionization to prepare the novel nanoplatform, CTX@HPDA, for DAH treatment. The monodisperse silica nanoparticles were acquired by reference to the typical Stober method. PDA was coated on the surface of SiO₂ by oxidation self-polymerization method to obtain SiO₂@PDA NPs. Then, HPDA NPs were obtained by HF etching. Then HPDA was loaded with CTX by ionization to prepare CTX@HPDA. Then we tested the photothermal effect, animal model therapeutics effect, and biosafety of CTX@HPDA. Results: Material tests showed that the CTX@ HPDA nanoplatform had a uniform diameter and could release CTX in acidic environments. The vitro experiments demonstrated that CTX@HPDA has good photothermal conversion ability and photothermal stability. Animal experiments demonstrated that the CTX@HPDA nanoplatform had good biocompatibility. The nanoplatform can dissociate in acidic SLE environment and trigger CTX release through photothermal conversion. Combining HPDA, which scavenges oxygen free radicals, and CTX, which has immunosuppressive effect, can treat pulmonary hemorrhage in SLE. Micro-CT can be used to continuously analyze DAH severity and lung changes in mice after treatment. The pulmonary exudation in the various treatment groups improved to varying degrees. Discussion: In this study, we report a photothermal/PH-triggered nanocarrier (CTX@HPDA) for the precise treatment of SLE-DAH. CTX@HPDA is a simple and efficient nanocarrier system for DAH therapy. This work provides valuable insights into SLE treatment.

Polydopamine-Pd nanozymes as potent ROS scavengers in combination with near-infrared irradiation for osteoarthritis treatment

Excessive reactive oxygen species (ROS) in joints could lead to gradual degeneration of the extracellular matrix (ECM) and apoptosis of chondrocytes, contributing to the occurrence and development of osteoarthritis (OA). Mimicking natural enzymes, polydopamine (PDA)-based nanozymes showed great potential in treating various inflammatory diseases. In this work, PDA loaded with ultra-small palladium (PDA-Pd) nanoparticles (NPs) was employed to scavenge ROS for OA therapy. As a result, PDA-Pd effectively declined the intracellular ROS levels and exhibited efficient antioxidative and anti-inflammatory capacity with good biocompatibility in IL-1β stimulated chondrocytes. Significantly, assisted with near-infrared (NIR) irradiation, its therapeutic effect was further enhanced. Further, NIR-stimulated PDA-Pd suppressed the progression of OA after intra-articular injection in the OA rat model. With favorable biocompatibility, PDA-Pd exhibits efficient antioxidative and anti-inflammatory capacity, leading to the alleviation of OA in rats. Our findings may provide new insights into the treatment of various ROS-induced inflammatory diseases.

MRI-visible mesoporous polydopamine nanoparticles with enhanced antioxidant capacity for osteoarthritis therapy

Since the progression of osteoarthritis (OA) is closely associated with synovitis and cartilage destruction, the inhibition of inflammatory responses in synovial macrophages and reactive oxygen species (ROS) induced apoptosis in chondrocytes is crucial for OA amelioration. However, most of the current anti-inflammatory and antioxidant drugs are small molecules apt to be eliminated in vivo. Herein, mesoporous polydopamine nanoparticles (DAMM NPs) doped with arginine and manganese (Mn) ions were prepared to load dexamethasone (DEX) for OA intervention. A series of in vitro studies showed that the sustained release of DEX from DAMM NPs suppressed synovial inflammation and simultaneously inhibited toll-like receptor 3 (TLR-3) production in chondrocytes, contributing to prevention of chondrocyte apoptosis through the inflammatory factor-dependent TLR-3/NF-κB signaling pathway via modulation of macrophage-chondrocyte crosstalk. In addition, DAMM NPs exerted a predominant role in removal of ROS generated in chondrocytes. Therefore, the DEX-loaded DAMM NPs significantly attenuated OA development in mice model. Importantly, the T1-T2 magnetic contrast capabilities of DAMM NPs allowed an MRI-trackable delivery, manifesting a distinct feature widely regarded to boost the potential of nanomedicines for clinical applications. Together, our developed antioxidant-enhanced DAMM NPs with MRI-visible signals may serve as a novel multifunctional nanocarriers for prevention of OA progression.

Magnetic Response Combined with Bioactive Ion Therapy: A RONS-Scavenging Theranostic Nanoplatform for Thrombolysis and Renal Ischemia-Reperfusion Injury

Currently, the limited efficacy of antithrombotic treatments is attributed to the inadequacy of pure drugs and the low ability of drugs to target the thrombus site. More importantly, timely thrombolysis is essential to reduce the sequelae of cardiovascular disease, but ischemia-reperfusion injury (IRI) remains a major challenge that must be solved after blood flow recovery. Herein, a multifunctional therapeutic nanoparticle (NP) based on Fe₃O₄ and strontium ions encapsulated in mesoporous polydopamine was successfully constructed and then loaded with TNK-tPA (FeM@Sr-TNK NPs). The NPs (59.9 min) significantly prolonged the half-life of thrombolytic drugs, which was 3.04 times that of TNK (19.7 min), and they had good biological safety. The NPs were shown to pass through vascular models with different inner diameters, curvatures, and stenosis under magnetic targeting and to enable accurate diagnosis of thrombi by photoacoustic imaging. NPs combined with the magnetic hyperthermia technique were used to accelerate thrombolysis and quickly open blocked blood vessels. Then, renal IRI-induced functional metabolic disorder and tissue damage were evidently attenuated by scavenging toxic reactive oxygen and nitrogen species and through the protective effects of bioactive ion therapy, including reduced apoptosis, increased angiogenesis, and inhibited fibrosis. In brief, we constructed a multifunctional nanoplatform for integrating a "diagnosis-therapy-protection" approach to achieve comprehensive management from thrombus to renal IRI, promoting the advancement of related technologies.

Advances of Mussel-Inspired Nanocomposite Hydrogels in Biomedical Applications

Hydrogels, with 3D hydrophilic polymer networks and excellent biocompatibilities, have emerged as promising biomaterial candidates to mimic the structure and properties of biological tissues. The incorporation of nanomaterials into a hydrogel matrix can tailor the functions of the nanocomposite hydrogels to meet the requirements for different biomedical applications. However, most nanomaterials show poor dispersion in water, which limits their integration into the hydrophilic hydrogel network. Mussel-inspired chemistry provides a mild and biocompatible approach in material surface engineering due to the high reactivity and universal adhesive property of catechol groups. In order to attract more attention to mussel-inspired nanocomposite hydrogels, and to promote the research work on mussel-inspired nanocomposite hydrogels, we have reviewed the recent advances in the preparation of mussel-inspired nanocomposite hydrogels using a variety of nanomaterials with different forms (nanoparticles, nanorods, nanofibers, nanosheets). We give an overview of each nanomaterial modified or hybridized by catechol or polyphenol groups based on mussel-inspired chemistry, and the performances of the nanocomposite hydrogel after the nanomaterial's incorporation. We also highlight the use of each nanocomposite hydrogel for various biomedical applications, including drug delivery, bioelectronics, wearable/implantable biosensors, tumor therapy, and tissue repair. Finally, the challenges and future research direction in designing mussel-inspired nanocomposite hydrogels are discussed.

A multifunctional hydrogel loaded with two nanoagents improves the pathological microenvironment associated with radiation combined with skin wounds

Persistent oxidative stress and recurring waves of inflammation with excessive reactive oxygen species (ROS) and free radical accumulation could be generated by radiation. Exposure to radiation in combination with physical injuries such as wound trauma would produce a more harmful set of medical complications, which was known as radiation combined with skin wounds (RCSWs). However, little attention has been given to RCSW research despite the unsatisfactory therapeutic outcomes. In this study, a dual-nanoagent-loaded multifunctional hydrogel was fabricated to ameliorate the pathological microenvironment associated with RCSWs. The injectable, adhesive, and self-healing hydrogel was prepared by crosslinking carbohydrazide-modified gelatin (Gel-CDH) and oxidized hyaluronic acid (OHA) through the Schiff-base reaction under mild condition. Polydopamine nanoparticles (PDA-NPs) and mesenchymal stem cell-secreted small extracellular vesicles (MSC-sEV) were loaded to relieve radiation-produced tissue inflammation and oxidation impairment and enhance cell vitality and angiogenesis individually or jointly. The proposed PDA-NPs@MSC-sEV hydrogel enhanced cell vitality, as shown by cell proliferation, migration, colony formation, and cell cycle and apoptosis assays in vitro, and promoted reepithelization by attenuating microenvironment pathology in vivo. Notably, a gene set enrichment analysis of proteomic data revealed significant enrichment with adipogenic and hypoxic pathways, which play prominent roles in wound repair. Specifically, target genes were predicted based on differential transcription factor expression. The results suggested that MSC-sEV- and PDA-NP-loaded multifunctional hydrogels may be promising nanotherapies for RCSWs. STATEMENT OF SIGNIFICANCE: The small extracellular vesicle (sEV) has distinct advantages compared with MSCs, and polydopamine nanoparticles (PDA-NPs), known as the biological materials with good cell affinity and histocompatibility which have been reported to scavenge ROS free radicals. In this study, an adhesive, injectable, self-healing, antibacterial, ROS scavenging and amelioration of the radiation related microenvironment hydrogel encapsulating nanoscale particles of MSC-sEV and PDA-NPs (PDA-NPs@MSC-sEV hydrogel) was synthesized for promoting radiation combined with skin wounds (RCSWs). GSEA analysis profiled by proteomics data revealed significant enrichments in the regulations of adipogenic and hypoxic pathways with this multi-functional hydrogel. This is the first report of combining this two promising nanoscale agents for the special skin wounds associated with radiation.

Injectable multifunctional hydrogel based on carboxymethylcellulose/polyacrylamide/polydopamine containing vitamin C and curcumin promoted full-thickness burn regeneration

Burn injuries are a major global problem, with a high risk of infection and mortality. This study aimed to develop an injectable hydrogel for wound dressings, composed of sodium carboxymethylcellulose/polyacrylamide/polydopamine containing vitamin C (CMC/PAAm/PDA ^VitC) for its antioxidant and antibacterial properties. Simultaneously, silk fibroin/alginate nanoparticles (SF/SANPs) loaded with curcumin (SF/SANPs ^CUR) were incorporated into the hydrogel to enhance wound regeneration and reduce bacterial infection. The hydrogels were fully characterized and tested in vitro and in preclinical rat models for biocompatibility, drug release, and wound healing efficacy. Results showed stable rheological properties, appropriate swelling and degradation ratios, gelation time, porosity, and free radical scavenging capacity. Biocompatibility was confirmed through MTT, lactate dehydrogenase, and apoptosis evaluations. Hydrogels containing curcumin demonstrated antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). In the preclinical study, hydrogels containing both drugs showed superior support for full-thickness burn regeneration, with improved wound closure, re-epithelialization, and collagen expression. The hydrogels also showed neovascularization and anti-inflammatory effects, as confirmed by CD31 and TNF-α markers. In conclusion, these dual drug-delivery hydrogels showed significant potential as wound dressings for full-thickness wounds.

Accelular nanofibrous bilayer scaffold intrapenetrated with polydopamine network and implemented into a full-thickness wound of a white-pig model affects inflammation and healing process

Treatment of complete loss of skin thickness requires expensive cellular materials and limited skin grafts used as temporary coverage. This paper presents an acellular bilayer scaffold modified with polydopamine (PDA), which is designed to mimic a missing dermis and a basement membrane (BM). The alternate dermis is made from freeze-dried collagen and chitosan (Coll/Chit) or collagen and a calcium salt of oxidized cellulose (Coll/CaOC). Alternate BM is made from electrospun gelatin (Gel), polycaprolactone (PCL), and CaOC. Morphological and mechanical analyzes have shown that PDA significantly improved the elasticity and strength of collagen microfibrils, which favorably affected swelling capacity and porosity. PDA significantly supported and maintained metabolic activity, proliferation, and viability of the murine fibroblast cell lines. The in vivo experiment carried out in a domestic Large white pig model resulted in the expression of pro-inflammatory cytokines in the first 1-2 weeks, giving the idea that PDA and/or CaOC trigger the early stages of inflammation. Otherwise, in later stages, PDA caused a reduction in inflammation with the expression of the anti-inflammatory molecule IL10 and the transforming growth factor β (TGFβ1), which could support the formation of fibroblasts. Similarities in treatment with native porcine skin suggested that the bilayer can be used as an implant for full-thickness skin wounds and thus eliminate the use of skin grafts.

GDNF-Loaded Polydopamine Nanoparticles-Based Anisotropic Scaffolds Promote Spinal Cord Repair by Modulating Inhibitory Microenvironment

Spinal cord injury (SCI) is a devastating injury that causes permanent loss of sensation and motor function. SCI repair is a significant challenge due to the limited regenerating ability of adult neurons and the complex inflammatory microenvironment. After SCI, the oxidative stress induced by excessive reactive oxygen species (ROS) often leads to prolonged neuroinflammation that results in sustained damage to the spinal cord tissue. Polydopamine (PDA) shows remarkable capability in scavenging ROS to treat numerous inflammatory diseases. In this study, glial cell-derived neurotrophic factor (GDNF)-loaded PDA nanoparticle-based anisotropic scaffolds for spinal cord repair are developed. It is found that mesoporous PDA nanoparticles (mPDA NPs) in the scaffolds efficiently scavenge ROS and promote microglia M2 polarization, thereby inhibiting inflammatory response at the injury site and providing a favorable microenvironment for nerve cell survival. Furthermore, the GDNF encapsulated in mPDA NPs promotes corticospinal tract motor axon regeneration and its locomotor functional recovery. Together, findings from this study reveal that the GDNF-loaded PDA/Gelatin scaffolds hold potential as an effective artificial transplantation material for SCI treatment.

Melanin-like polydopamine nanoparticles mediating anti-inflammatory and rescuing synaptic loss for inflammatory depression therapy

Inflammatory depression is closely related to neuroinflammation. However, current anti-inflammatory drugs have low permeability to cross blood-brain barrier with difficulties reaching the central nervous system to provide therapeutic effectiveness. To overcome this limitation, the nano-based drug delivery technology was used to synthesize melanin-like polydopamine nanoparticles (PDA NPs) (~ 250 nm) which can cross the blood-brain barrier. Importantly, PDA NPs with abundant phenolic hydroxyl groups function as excellent free radical scavengers to attenuate cell damage caused by reactive oxygen species or acute inflammation. In vitro experiments revealed that PDA NPs exhibited excellent antioxidative properties. Next, we aimed to investigate the therapeutic effect of PDA NPs on inflammatory depression through intraperitoneal injection to the lipopolysaccharide-induced inflammatory depression model in mice. PDA NPs significantly reversed the depression-like behavior. PDA NPs was also found to reduce the peripheral and central inflammation induced by LPS, showing that alleviated splenomegaly, reduced serum inflammatory cytokines, inhibited microglial activation and restored synaptic loss. Various experiments also showed that PDA NPs had good biocompatibility both in vivo and in vitro. Our work suggested that PDA NPs may be biocompatible nano-drugs in treating inflammatory depression but their clinical application requires further study.

Skin Interstitial Fluid-Based SERS Tags Labeled Microneedles for Tracking of Peritonitis Progression and Treatment Effect

Skin interstitial fluid (ISF)-based microneedle (MN) sensing has recently exhibited wide promise for the minimally invasive and painless diagnosis of diseases. However, it is still a great challenge to diagnose more disease types due to the limited in situ sensing techniques and insufficient ISF biomarker sources. Herein, ISF is employed to pioneer the tracking of acute peritonitis progression via surface-enhanced Raman scattering (SERS) tags labeled MNs patch technique. Densely deposited core-satellite gold nanoparticles and 3-mercaptophenylboronic acid as a Raman reporter enable the developed MNs patch with high sensitivity and selectivity in the determination of H₂O₂, an indicator of peritonitis development. Importantly, the MNs patch not only reliably tracks the different states of peritonitis but also evaluates the efficacy of drugs in the treatment of peritonitis, as evidenced by the altered SERS signal consistent with plasma pro-inflammatory factor (TNF-α) and peritoneum pathological manifestations. Interestingly, the major source of H₂O₂ in ISF of acute peritonitis investigated may not be through conventional blood capillary filtration pathway. This work provides a new route and technique for the early diagnosis of acute peritonitis and the evaluation of drug therapy effects. The developed MNs patch is promising to serve as a universal sensing tool to greatly enrich the variety and prospect of ISF-based disease diagnosis.

Ultra-small polydopamine nanomedicine-enabled antioxidation against senescence

Senescence is a cellular response characterized by cells irreversibly stopping dividing and entering a state of permanent growth arrest. One of the underlying pathophysiological causes of senescence is the oxidative stress-induced damage, indicating that eliminating the reactive oxygen and nitrogen species (RONS) may be beneficial to prevent and/or alleviate senescence. Herein, we developed ultra-small polydopamine nanoparticles (UPDA NPs) with superoxide dismutase (SOD)/catalase (CAT) enzyme-mimic activities, featuring broad-spectrum RONS-scavenging capability for inducing cytoprotective effects against RONS-mediated damage. The engineered UPDA NPs can restore senescence-related renal function, tissue homeostasis, fur density, and motor ability in mice, potentially associated with the regulation of multiple genes involved in lipid metabolism, mitochondrial function, energy homeostasis, telomerase activity, neuroprotection, and inflammatory responses. Importantly, the dietary UPDA NPs can enhance the antioxidant capacity, improve the climbing ability, and prolong the lifespan of Drosophila. Notably, UPDA NPs possess excellent biocompatibility stemming from the ultra-small size, ensuring quick clearance out of the body. These findings reveal that UPDA NPs can delay aging through reducing oxidative stress and provide a paradigm and practical strategy for treating senescence and senescence-related diseases.

Carboxymethyl chitosan/sodium alginate hydrogels with polydopamine coatings as promising dressings for eliminating biofilm and multidrug-resistant bacteria induced wound healing

Microorganisms induced wound infection and the accompanying excessive inflammatory response is the daunting problems in wound treatment. Due to the lack of corresponding biological functions, traditional wound dressings cannot effectively protect the wound and are prone to induce local infection, excessive inflammation, and vascular damage, resulting in prolonged unhealing. Here, a mussel-inspired strategy was adopted to prepare a multifunctional hydrogel created by H₂O₂/CuSO₄-induced rapid polydopamine (PDA) deposition on carboxymethyl chitosan (CMC)/sodium alginate (Alg) based hydrogel, termed as CAC/PDA/Cu(H₂O₂). The prepared CAC/PDA/Cu(H₂O₂) hydrogel features excellent biocompatibility, adequate mechanical properties, and good degradability. Moreover, the CAC/PDA/Cu(H₂O₂) hydrogel can not only realize antibacterial, and anti-inflammatory effects, but also promote angiogenesis to accelerate wound healing in vitro thanks to the composite PDA/Cu(H₂O₂) coatings. Significantly, CAC/PDA/Cu(H₂O₂) hydrogel illustrates excellent therapeutic effects in Methicillin-resistant Staphylococcus aureus (MRSA) induced-rat infection models, which can efficiently eliminate MRSA, dramatically reduce inflammatory expression, promote angiogenesis, and ultimately shorten the wound healing time. CAC/PDA/Cu(H₂O₂) hydrogel exhibited the best wound healing rate on days 7 (80.63 ± 2.44 %), 11 (92.45 ± 2.26 %), and 14 (97.86 ± 0.66 %). Thus, the multifunctional hydrogel provides a facile and efficient approach to wound management and represents promising potential in the therapy for wound healing.

Oridonin inhibits inflammation of epithelial cells via dual-targeting of CD31 Keap1 to ameliorate acute lung injury

Introdcution

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are major causes of COVID-19 mortality. However, drug delivery to lung tissues is impeded by endothelial cell barriers, limiting the efficacy of existing treatments. A prompt and aggressive treatment strategy is therefore necessary.

Methods

We assessed the ability of anti-CD31-ORI-NPs to penetrate endothelial cell barriers and specifically accumulate in lung tissues using an animal model. We also compared the efficacy of anti-CD31-ORI-NPs to that of free oridonin in ameliorating acute lung injury and evaluated the cytotoxicity of both treatments on endothelial cells.

Results

Compared to free ORI, the amount of anti-CD31-ORI-NPs accumulated in lung tissues increase at least three times. Accordingly, anti-CD31-ORI-NPs improve the efficacy three times on suppressing IL-6 and TNF-a secretion, ROS production, eventually ameliorating acute lung injury in animal model. Importantly, anti-CD31-ORI-NPs significantly decrease the cytotoxicity at least two times than free oridonin on endothelial cells.

Discussion

Our results from this study will not only offer a novel therapeutic strategy with high efficacy and low toxicity, but also provide the rational design of nanomaterials of a potential drug for acute lung injury therapy.

Melanin nanoparticles alleviate sepsis-induced myocardial injury by suppressing ferroptosis and inflammation

Myocardial injury as one of the severe complications leads to the increasing morbidity and mortality in patients with sepsis. Recent studies reported that reactive oxygen species (ROS)-mediated ferroptosis plays a critical role in the development of heart diseases. Therefore, we hypothesized that anti-ferroptosis agent might be a novel potential therapeutic strategy for sepsis-induced cardiac injury. Herein, we demonstrated that a small biocompatible and MRI-visible melanin nanoparticles (MMPP) improves myocardial function by inhibiting ROS-related ferroptosis signaling pathway. In LPS-induced murine sepsis model, after a single dose intravenously injection of MMPP treatment, MMPP markedly alleviated the myocardial injury including cardiac function and heart structure disorder through suppressing iron-accumulation induced ferroptosis. In vitro, MMPP inhibited cardiomyocyte death by attenuating oxidative stress, inflammation and maintaining mitochondrial homeostasis. Collectively, our findings demonstrated that MMPP protected heart against sepsis-induced myocardial injury via inhibiting ferroptosis and inflammation, which might be a novel therapeutic approach in future.

Sustained release of heme-albumin as a potential novel therapeutic approach for age-related macular degeneration

Globally, age-related macular degeneration (AMD) is the third most common visual impairment. Most often attributed to cellular fatigue with aging, over expression of reactive oxygen species (ROS) causes ROS accumulation in the retina, leading to chronic inflammatory immune signaling, cellular and tissue damage, and eventual blindness. If left uncontrolled, the disease will progress from the dry form of AMD to more severe forms such as geographic atrophy or wet AMD, hallmarked by choroidal neovascularization. There is no cure for AMD and treatment options are limited. Treatment options for wet AMD require invasive ocular injections or implants, yet fail to address the disease progressing factors. To provide more complete treatment of AMD, the application of a novel anti-inflammatory heme-bound human serum albumin (heme-albumin) protein complex delivered by antioxidant ROS scavenging polydopamine (PDA) nanoparticles (NPs) for sustained treatment of AMD was investigated. Through the induction of heme oxygenase-1 (HO-1) by heme-albumin in retinal pigment epithelial (RPE) cells, anti-inflammatory protection may be provided through the generation of carbon monoxide (CO) and biliverdin during heme catabolism. Our results show that the novel protein complex has negligible cytotoxicity towards RPE cells (ARPE-19), reduces oxidative stress in both inflammatory and ROS in vitro models, and induces a statistically significant increase in HO-1 protein expression. When incorporated into PDA NPs, heme-albumin was sustainably released for up to 6 months, showing faster release at higher oxidative stress levels. Through its ability to react with ROS, heme-albumin loaded PDA NPs showed further reduction of oxidative stress with minimal cytotoxicity. Altogether, we demonstrate that heme-albumin loaded PDA NPs reduce oxidative stress in vitro and can provide sustained therapeutic delivery for AMD treatment.

NIR-Assisted MgO-Based Polydopamine Nanoparticles for Targeted Treatment of Parkinson's Disease through the Blood-Brain Barrier

The blood-brain barrier (BBB) is a major limiting factor that prevents the treatment of Parkinson's disease (PD). In the present study, MgOp@PPLP nanoparticles are explored by using MgO nanoparticles as a substrate, polydopamine as a shell, wrapping anti-SNCA plasmid inside, and modifying polyethylene glycol, lactoferrin, and puerarin on the surface to improve the hydrophilicity, brain targeting and antioxidant properties of the particles, respectively. MgOp@PPLP exhibits superior near-infrared radiation (NIR) response. Under the guidance of photothermal effect, these MgOp@PPLP particles are capable of penetrating the BBB and be taken up by neuronal cells to exert gene therapy and antioxidant therapy. In both in vivo and in vitro models of PD, MgOp@PPLP exhibits good neuroprotective effects. Therefore, combined with noninvasive NIR radiation, MgOp@PPLP nanoplatform with good biocompatibility becomes an ideal material to combat neurodegenerative diseases.

Polydopamine-Coated Co3O4 Nanoparticles as an Efficient Catalase Mimic for Fluorescent Detection of Sulfide Ion

Surface engineering of nanozymes has been recognized as a potent strategy to improve their catalytic activity and specificity. We synthesized polydopamine-coated Co₃O₄ nanoparticles (PDA@Co₃O₄ NPs) through simple dopamine-induced self-assembly and demonstrated that these NPs exhibit catalase-like activity by decomposing H₂O₂ into oxygen and water. The activity of PDA@Co₃O₄ NPs was approximately fourfold higher than that of Co₃O₄ NPs without PDA, possibly due to the additional radical scavenging activity of the PDA shell. In addition, PDA@Co₃O₄ NPs were more stable than natural catalase under a wide range of pH, temperature, and storage time conditions. Upon the addition of a sample containing sulfide ion, the activity of PDA@Co₃O₄ NPs was significantly inhibited, possibly because of increased mass transfer limitations via the absorption of the sulfide ion on the PDA@Co₃O₄ NP surface, along with NP aggregation which reduced their surface area. The reduced catalase-like activity was used to determine the levels of sulfide ion by measuring the increased fluorescence of the oxidized terephthalic acid, generated from the added H₂O₂. Using this strategy, the target sulfide ion was sensitively determined to a lower limit of 4.3 µM and dynamic linear range of up to 200 µM. The fluorescence-based sulfide ion assay based on PDA@Co₃O₄ NPs was highly precise when applied to real tap water samples, validating its potential for conveniently monitoring toxic elements in the environment.

Antioxidant PDA-PEG nanoparticles alleviate early osteoarthritis by inhibiting osteoclastogenesis and angiogenesis in subchondral bone

Accumulating evidence suggests that osteoclastogenesis and angiogenesis in subchondral bone are critical destructive factors in the initiation and progression of osteoarthritis (OA). Herein, methoxypolyethylene glycol amine (mPEG-NH2) modified polydopamine nanoparticles (PDA-PEG NPs) were synthesized for treating early OA. The cytotoxicity and reactive oxygen species (ROS) scavenging ability of PDA-PEG NPs were evaluated. The effects of PDA-PEG NPs on osteoclast differentiation and vessel formation were then evaluated. Further, PDA-PEG NPs were administrated to anterior cruciate ligament transection (ACLT)-induced OA mice. Results demonstrated that PDA-PEG NPs had low toxicity both in vitro and in vivo. PDA-PEG NPs could inhibit osteoclastogenesis via regulating nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. Moreover, PDA-PEG NPs suppressed osteoclast-related angiogenesis via down-regulating platelet-derived growth factor-BB (PDGF-BB). In vivo, PDA-PEG NPs inhibited subchondral bone resorption and angiogenesis, further rescuing cartilage degradation in OA mice. In conclusion, we demonstrated that PDA-PEG NPs deployment could be a potential therapy for OA.

Graphical Abstract

Nanozymes in the Treatment of Diseases Caused by Excessive Reactive Oxygen Specie

Excessive reactive oxygen species (ROS) may generate deleterious effects on biomolecules, such as DNA damage, protein oxidation and lipid peroxidation, causing cell and tissue damage and eventually leading to the pathogenesis of diseases, such as neurodegenerative diseases, ischemia/reperfusion ((I/R)) injury, and inflammatory diseases. Therefore, the modulation of ROS can be an efficient means to relieve the aforementioned diseases. Several studies have verified that antioxidants such as Mitoquinone (a mitochondrial-targeted coenzyme Q10 derivative) can scavenge ROS and attenuate related diseases. Nanozymes, defined as nanomaterials with intrinsic enzyme-like properties that also possess antioxidant properties, are hence expected to be promising alternatives for the treatment of ROS-related diseases. This review introduces the types of nanozymes with inherent antioxidant activities, elaborates on various strategies (eg, controlling the size or shape of nanozymes, regulating the composition of nanozymes and environmental factors) for modulating their catalytic activities, and summarizes their performances in treating ROS-induced diseases.

Anti-inflammatory hydrogel dressings and skin wound healing

Hydrogels are promising and widely utilized in the biomedical field. In recent years, the anti-inflammatory function of hydrogel dressings has been significantly improved, addressing many clinical challenges presented in ongoing endeavours to promote wound healing. Wound healing is a cascaded and highly complex process, especially in chronic wounds, such as diabetic and severe burn wounds, in which adverse endogenous or exogenous factors can interfere with inflammatory regulation, leading to the disruption of the healing process. Although insufficient wound inflammation is uncommon, excessive inflammatory infiltration is an almost universal feature of chronic wounds, which impedes a histological repair of the wound in a predictable biological step and chronological order. Therefore, resolving excessive inflammation in wound healing is essential. In the past 5 years, extensive research has been conducted on hydrogel dressings to address excessive inflammation in wound healing, specifically by efficiently scavenging excessive free radicals, sequestering chemokines and promoting M₁ -to-M₂ polarization of macrophages, thereby regulating inflammation and promoting wound healing. In this study, we introduced novel anti-inflammatory hydrogel dressings and demonstrated innovative methods for their preparation and application to achieve enhanced healing. In addition, we summarize the most important properties required for wound healing and discuss our analysis of potential challenges yet to be addressed.

Application and prospect of ROS-related nanomaterials for orthopaedic related diseases treatment

The importance of reactive oxygen species (ROS) in the occurrence and development of orthopaedic related diseases is becoming increasingly prominent. ROS regulation has become a new method to treat orthopaedic related diseases. In recent years, the application of nanomaterials has become a new hope for precision and efficient treatment. However, there is a lack of reviews on ROS-regulated nanomaterials for orthopaedic related diseases. Based on the key significance of nanomaterials for the treatment of orthopaedic related diseases, we searched the latest related studies and reviewed the nanomaterials that regulate ROS in the treatment of orthopaedic related diseases. According to the function of nanomaterials, we describe the scavenging of ROS related nanomaterials and the generation of ROS related nanomaterials. In this review, we closely integrated nanomaterials with the treatment of orthopaedic related diseases such as arthritis, osteoporosis, wound infection and osteosarcoma, etc., and highlighted the advantages and disadvantages of existing nanomaterials. We also looked forward to the design of ROS-regulated nanomaterials for the treatment of orthopaedic related diseases in the future.