Zinc based metal organic framework with antibacterial and anti- inflammatory properties for promoting wound healing

Application of metal-organic frameworks in infectious wound healing

Metal-organic frameworks (MOFs) are metal-organic skeleton compounds composed of self-assembled metal ions or clusters and organic ligands. MOF materials often have porous structures, high specific surface areas, uniform and adjustable pores, high surface activity and easy modification and have a wide range of prospects for application. MOFs have been widely used. In recent years, with the continuous expansion of MOF materials, they have also achieved remarkable results in the field of antimicrobial agents. In this review, the structural composition and synthetic modification of MOF materials are introduced in detail, and the antimicrobial mechanisms and applications of these materials in the healing of infected wounds are described. Moreover, the opportunities and challenges encountered in the development of MOF materials are presented, and we expect that additional MOF materials with high biosafety and efficient antimicrobial capacity will be developed in the future.

MOFs and MOF-Based Composites as Next-Generation Materials for Wound Healing and Dressings

In recent years, there has been growing interest in developing innovative materials and therapeutic strategies to enhance wound healing outcomes, especially for chronic wounds and antimicrobial resistance. Metal-organic frameworks (MOFs) represent a promising class of materials for next-generation wound healing and dressings. Their high surface area, pore structures, stimuli-responsiveness, antibacterial properties, biocompatibility, and potential for combination therapies make them suitable for complex wound care challenges. MOF-based composites promote cell proliferation, angiogenesis, and matrix synthesis, acting as carriers for bioactive molecules and promoting tissue regeneration. They also have stimuli-responsivity, enabling photothermal therapies for skin cancer and infections. Herein, a critical analysis of the current state of research on MOFs and MOF-based composites for wound healing and dressings is provided, offering valuable insights into the potential applications, challenges, and future directions in this field. This literature review has targeted the multifunctionality nature of MOFs in wound-disease therapy and healing from different aspects and discussed the most recent advancements made in the field. In this context, the potential reader will find how the MOFs contributed to this field to yield more effective, functional, and innovative dressings and how they lead to the next generation of biomaterials for skin therapy and regeneration.

Alloy nanozyme-reinforced hyaluronic acid-based hydrogel with wound environment-responsive properties for synergistically accelerating infectious wound healing

The recovery of infectious wound tissues presents a significant global health challenge due to the impediments posed by the harsh healing microenvironment, which includes ongoing bacterial invasion, high oxidative stress, inflammatory response, and impaired angiogenesis. To overcome the above issues, we propose a composite hydrogel based on the multiple-crosslinked mechanism involving the covalent network of CC bonds within catechol and maleic-modified HA (CMHA), the self-assembly network of glycyrrhizic acid (GA), and the metal-polyphenol coordination induced by ZHMCe for accelerating infectious wound healing. The resulting CMHA/GA/ZHMCe hydrogels demonstrate enhanced mechanical, adhesive, antioxidative, and antibacterial properties. Importantly, the hydrogel system possesses wound environment-responsive properties that allow it to adapt to the specific therapeutic requirements of different stages by regulating various enzyme activities in the healing of infected wounds. Furthermore, the biocompatible CMHA/GA/ZHMCe shows the ability to promote cell migration and angiogenesis in vitro while reprogramming macrophages toward an anti-inflammatory phenotype due to the effective release of active ingredients. In vivo experiments confirm that the CMHA/GA/ZHMCe hydrogel significantly enhances infectious wound healing by accelerating re-epithelialization, promoting collagen deposition, regulating inflammation, and contributing to vascularization. These findings underscore the therapeutic potential of our hydrogel dressings for the treatment of bacterially infected cutaneous wound healing.

Recent advances and potential applications for metal-organic framework (MOFs) and MOFs-derived materials: Characterizations and antimicrobial activities

Microbial infections, particularly those caused by antibiotic-resistant pathogens, pose a critical global health threat. Metal-Organic Frameworks (MOFs), porous crystalline structures built from metal ions and organic linkers, initially developed for gas adsorption, have emerged as promising alternatives to traditional antibiotics. This review, covering research up to 2023, explores the potential of MOFs and MOF-based materials as broad-spectrum antimicrobial agents against bacteria, viruses, fungi, and even parasites. It delves into the historical context of antimicrobial agents, recent advancements in MOF research, and the diverse synthesis techniques employed for their production. Furthermore, the review comprehensively analyzes the mechanisms of action by which MOFs combat various microbial threats. By highlighting the vast potential of MOFs, their diverse synthesis methods, and their effectiveness against various pathogens, this study underscores their potential as a novel solution to the growing challenge of antibiotic resistance.

Design and development of pH-responsive levofloxacin-loaded metal-organic framework for the promising treatment of pediatric abdominal wound repair

With over 9 million fatalities per year expected by 2030, infectious diseases will remain a significant burden on the world economy and cause high mortality rates. An excellent method to increase the bioactivity of levofloxacin (LEV) in pediatric abdominal wound repair is the finding of a stimuli-based drug delivery system (DDS). We designed and developed an LEV incorporated with zeolite imidazole framework-8 (ZIF-8) as a promising nanocarrier for wound healing applications. The spectral analysis and morphological analysis confirm the formation of our newly fabricated composites. Mouse embryonic fibroblast NIH3T3 cells, the cytotoxicity, cytocompatibility, and cell proliferation characteristics of LEV@ZIF-8 were evaluated in vitro. LEV@ZIF-8 composite considerably improved the biocompatibility against NIH3T3 cells after 72-h of exposure, according to in vitro experiments. Under acidic circumstances, the pH-responsive drug release studies exhibit superior LEV release, and in physiological circumstances, there is no unintended drug release. The LEV@ZIF-8 composite-treated cells demonstrate the most remarkable cell growth and migration method in a very short time, according to the results of the wound scratch experiment. The composite exposure concentration depended on inhibition against various microorganisms in the antibacterial activity testing. According to the study, LEV@ZIF-8 are appropriate and effective DDS for stimuli-based pediatric abdominal wound repair.

UiO-66(Zr) as drug delivery system for non-steroidal anti-inflammatory drugs

The toxicity for the human body of non-steroidal anti-inflammatory drugs (NSAIDs) overdoses is a consequence of their low water solubility, high doses, and facile accessibility to the population. New drug delivery systems (DDS) are necessary to overcome the bioavailability and toxicity related to NSAIDs. In this context, UiO-66(Zr) metal-organic framework (MOF) shows high porosity, stability, and load capacity, thus being a promising DDS. However, the adsorption and release capability for different NSAIDs is scarcely described. In this work, the biocompatible UiO-66(Zr) MOF was used to study the adsorption and release conditions of ibuprofen, naproxen, and diclofenac using a theoretical and experimental approximation. DFT results showed that the MOF-drug interaction was due to an intermolecular hydrogen bond between protons of the groups in the defect sites, (μ3 - OH, and - OH2) and a lone pair of oxygen carboxyl functional group of the NSAIDs. Also, the experimental results suggest that the solvent where the drug is dissolved affects the adsorption process. The adsorption kinetics are similar between the drugs, but the maximum load capacity differs for each drug. The release kinetics assay showed a solvent dependence kinetics whose maximum liberation capacity is affected by the interaction between the drug and the material. Finally, the biological assays show that none of the systems studied are cytotoxic for HMVEC. Additionally, the wound healing assay suggests that the UiO-66(Zr) material has potential application on the wound healing process. However, further studies should be done.

Structural and temporal dynamics analysis of zinc-based biomaterials: History, research hotspots and emerging trends

Objectives

To examine the 16-year developmental history, research hotspots, and emerging trends of zinc-based biodegradable metallic materials from the perspective of structural and temporal dynamics.

Methods

The literature on zinc-based biodegradable metallic materials in WoSCC was searched. Historical characteristics, the evolution of active topics and development trends in the field of zinc-based biodegradable metallic materials were analyzed using the bibliometric tools CiteSpace and HistCite.

Results

Over the past 16 years, the field of zinc-based biodegradable metal materials has remained in a hotspot stage, with extensive scientific collaboration. In addition, there are 45 subject categories and 51 keywords in different research periods, and 80 papers experience citation bursts. Keyword clustering anchored 3 emerging research subfields, namely, #1 plastic deformation #4 additive manufacturing #5 surface modification. The keyword alluvial map shows that the longest-lasting research concepts in the field are mechanical property, microstructure, corrosion behavior, etc., and emerging keywords are additive manufacturing, surface modification, dynamic recrystallization, etc. The most recent research on reference clustering has six subfields. Namely, #0 microstructure, #2 sem, #3 additive manufacturing, #4 laser powder bed fusion, #5 implant, and #7 Zn-1Mg.

Conclusion

The results of the bibliometric study provide the current status and trends of research on zinc-based biodegradable metallic materials, which can help researchers identify hot spots and explore new research directions in the field.

Polyhedral Oligomeric Sesquioxane Cross-Linked Chitosan-Based Multi-Effective Aerogel Preparation and Its Water-Driven Recovery Mechanism

The use of environmentally friendly and non-toxic biomass-based interfacial solar water evaporators has been widely reported as a method for water purification in recent years. However, the poor stability of the water transport layer made from biomass materials and its susceptibility to deformation when exposed to harsh environments limit its practical application. To address this issue, water-driven recovery aerogel (PCS) was prepared by cross-linking epoxy-based polyhedral oligomeric silsesquioxane (EP-POSS) epoxy groups with chitosan (CS) amino groups. The results demonstrate that PCS exhibits excellent water-driven recovery performance, regaining its original volume within a very short time (1.9 s) after strong compression (ε > 80%). Moreover, PCS has a water absorption rate of 2.67 mm s-1 and exhibits an excellent water absorption capacity of 22.09 g g-1 even after ten cycles of absorption-removal. Furthermore, a photothermal evaporator (PCH) was prepared by loading the top layer with hydrothermally reacted tannins (HAs) and Zn2+ complexes. The results indicate that PCH achieves an impressive evaporation rate of 1.89 kg m-2 h-1 under one sun illumination. Additionally, due to the antimicrobial properties of Zn2+, PCH shows inhibitory effects against Staphylococcus aureus and Escherichia coli, thereby extending the application of solar water evaporators to include antimicrobial purification in natural waters.

Cuprorivaite/hardystonite/alginate composite hydrogel with thermionic effect for the treatment of peri-implant lesion

Peri-implant lesion is a grave condition afflicting numerous indi-viduals with dental implants. It results from persistent periodontal bacteria accumulation causing inflammation around the implant site, which can primarily lead to implant loosening and ultimately the implant loss. Early-stage peri-implant lesions exhibit symptoms akin to gum disease, including swelling, redness and bleeding of the gums surrounding the implant. These signs indicate infection and inflammation of the peri-implant tissues, which may result in bone loss and implant failure. To address this problem, a thermionic strategy was applied by designing a cuprorivaite-hardystonite bioceramic/alginate composite hydrogel with photothermal and Cu/Zn/Si multiple ions releasing property. This innovative approach creates a thermionic effect by the release of bioactive ions (Cu2+ and Zn2+ and SiO 3 2 - ) from the composite hydrogel and the mild heat environment though the photothermal effect of the composite hydrogel induced by near-infrared light irradiation. The most distinctive advantage of this thermionic effect is to substantially eliminate periodontal pathogenic bacteria and inhibit inflammation, while simultaneously enhance peri-implant osseointegration. This unique attribute renders the use of this composite hydrogel highly effective in significantly improving the survival rate of implants after intervention in peri-implant lesions, which is a clinical challenge in periodontics. This study reveals application potential of a new biomaterial-based approach for peri-implant lesion, as it not only eliminates the infection and inflammation, but also enhances the osteointegration of the dental implant, which provides theoretical insights and practical guidance to prevent and manage early-stage peri-implant lesion using bioactive functional materials.

Antibacterial, antibiofilm, and antioxidant activities of two novel metal-organic frameworks (MOFs) based on 4,6-diamino-2-pyrimidinethiol with Zn and Co metal ions as coordination polymers

In the present era, the increase in free radical species (FRs) and multidrug-resistant (MDR) bacteria represents a major worldwide concern for public health. Biofilm development and the overuse and misuse of antibiotics could lead to the adaptation of bacteria to antimicrobial agents. Consequently, finding novel multifunctional species with antibacterial, antioxidant, and antibiofilm properties has become crucial in the fight against challenging bacterial infections and chronic inflammatory conditions. Metal-organic frameworks (MOFs) with zinc and cobalt metal centers are widely utilized in biological and environmental remediation owing to their versatility. In this study, multifunctional Zn-MOFs and Co-MOFs were successfully synthesized with zinc and cobalt as metal centers and 4,6-diamino-2-pyrimidinethiol as an organic linker using a hydrothermal technique. Numerous characterization techniques were used to fully examine the MOF structure, functionality, chemical makeup, crystalline structure, surface appearance, thermal behavior, and magnetic characteristics; the techniques included XPS, PXRD, FTIR, FESEM, EDX, UV-visible, BET, BJH, TGA/DTG, DSC, and magnetic susceptibility measurement. The antioxidant, antibacterial, and antibiofilm activities of the MOFs were examined, and they demonstrated potent activity in each of these aspects. The proposed mechanisms of antibacterial activity suggest that bacterial cell death results from multiple toxic effects, including electrostatic interaction and lipid peroxidation, when MOFs are attached to bacteria, leading to the formation of reactive oxygen species (ROSs). Zn-MOFs exhibit high antibacterial and antibiofilm efficacy owing to their large surface-to-volume ratio and porous nature, while Co-MOFs exhibit high antioxidant capacity owing to their redox properties.

Development of collagen-chitosan dressing gel functionalized with propolis-zinc oxide nanoarchitectonics to accelerate wound healing

Using an in situ sol-gel technique, new nanoarchitectonics of propolis loaded zinc oxide nanoarchitectonics (PP/ZnO-NPs) were developed in order to improve the in vivo outcomes of collagen-chitosan gel in wounded rats. The obtained nanoarchitectonics were fully characterized. The XRD results indicate the presence of a Zincite phase for ZnO-NPs and Zincite accompanied by a minor amount of zinc hydroxide for PP/ZnO-NPs samples. While the TEM findings illustrate the transfer of the ZnO-NPs from agglomerated spheres with an average particle size of 230 ± 29 nm to needle-like NPs of 323 ± 173 nm length (PP1/ZnO-NPs) and to a sheet-like NPs of 500 ± 173 nm diameter (PP2/ZnO-NPs). In addition, the incorporation of PP results in an increase in the surface negativity of ZnO-NPs to -31.4 ± 6.4 mV for PP2/ZnO-NPs. The antimicrobial activities of the nanocomposite gel loaded with 10%PP1/ZnO-NPs (G6) revealed the highest inhibition zone against E. coli (26 ± 2.31 mm). Remarkably, the in vivo outcomes showed that the nanocomposite gel (G6) has exceptional collagen deposition, quick wound closure rates, and re-epithelization. The outcomes demonstrate the nanocomposite gel encouraging biological properties for the treatment of damaged and infected wounds.

Zirconium-Based Metal-Organic Framework Capable of Binding Proinflammatory Mediators in Hydrogel Form Promotes Wound Healing Process through a Multiscale Adsorption Mechanism

The regulation of proinflammatory mediators has been explored to promote natural healing without abnormal inflammation or autoimmune response induced by their overproduction. However, most efforts to control these mediators have relied on pharmacological substances that are directly engaged in biological cycles. It is believed that functional porous materials removing target mediators provide a new way to promote the healing process using their adsorption mechanisms. In this study, the Zr-based metal-organic frameworks (MOF)-808 (Zr6 O4 (OH)4 (BTC)2 (HCOO)6 ) crystals are found to be effective at removing proinflammatory mediators, such as nitric oxide (NO), cytokines, and reactive oxygen species (ROS) in vitro and in vivo, because of their porous structure and surface affinity. The MOF-808 crystals are applied to an in vivo skin wound model as a hydrogel dispersion. Hydrogel containing 0.2 wt% MOF-808 crystals shows significant improvement in terms of wound healing efficacy and quality over the corresponding control. It is also proven that the mode of action is to remove the proinflammatory mediators in vivo. Moreover, the application of MOF-808-containing hydrogels promotes cell activation, proliferation and inhibits chronic inflammation, leading to increased wound healing quality. These findings suggest that Zr-based MOFs may be a promising drug-free solution for skin problems related to proinflammatory mediators.

Injectable and self-healable nano-architectured hydrogel for NIR-light responsive chemo- and photothermal bacterial eradication

Hydrogels with multifunctional properties activated at specific times have gained significant attention in the biomedical field. As bacterial infections can cause severe complications that negatively impact wound repair, herein, we present the development of a stimuli-responsive, injectable, and in situ-forming hydrogel with antibacterial, self-healing, and drug-delivery properties. In this study, we prepared a Pluronic F-127 (PF127) and sodium alginate (SA)-based hydrogel that can be targeted to a specific tissue via injection. The PF127/SA hydrogel was incorporated with polymeric short-filaments (SFs) containing an anti-inflammatory drug - ketoprofen, and stimuli-responsive polydopamine (PDA) particles. The hydrogel, after injection, could be in situ gelated at the body temperature, showing great in vitro stability and self-healing ability after 4 h of incubation. The SFs and PDA improved the hydrogel injectability and compressive strength. The introduction of PDA significantly accelerated the KET release under near-infrared light exposure and extended its release validity period. The excellent composites' photo-thermal performance led to antibacterial activity against representative Gram-positive and Gram-negative bacteria, resulting in 99.9% E. coli and S. aureus eradication after 10 min of NIR light irradiation. In vitro, fibroblast L929 cell studies confirmed the materials' biocompatibility and paved the way toward further in vivo and clinical application of the system for chronic wound treatments.

A novel cartilage-targeting MOF-HMME-RGD sonosensitizer combined with sonodynamic therapy to enhance chondrogenesis and cartilage regeneration

Articular cartilage regeneration is still a difficult task due to the cartilage's weak capacity for self-healing and the effectiveness of the available therapies. The engineering of cartilage tissue has seen widespread use of stem cell-based therapies. However, efficient orientation of line-specific bone marrow mesenchymal stem cells (BMSCs) to chondrogenesis and maintenance of chondrogenic differentiation challenged stem cell-based therapy. Herein, we developed a Fe-based metal-organic framework (MOF) loaded with hematoporphyrin monomethyl ether (HMME) and cartilage-targeting arginine-aspartate-glycine (RGD) peptide to form MOF-HMME-RGD sonosensitizer to regulate BMSCs chondrogenic differentiation for cartilage regeneration via the modulation of reactive oxygen species (ROS). By using sonodynamic therapy (SDT), the MOF-HMME-RGD demonstrated favorable biocompatibility, could generate a modest amount of ROS, and enhanced BMSCs chondrogenic differentiation through increased accumulation of glycosaminoglycan, an ECM component specific to cartilage, and upregulated expression of key chondrogenic genes (ACAN, SOX9, and Col2a1). Further, transplanted BMSCs loading MOF-HMME-RGD combined with SDT enhanced cartilage regeneration for cartilage defect repair after 8 weeks into treatment. This synergistic strategy based on MOF nanoparticles provides an instructive approach to developing alternative sonosensitizers for cartilage regeneration combined with SDT.

Application of metal-organic frameworks-based functional composite scaffolds in tissue engineering

With the rapid development of materials science and tissue engineering, a variety of biomaterials have been used to construct tissue engineering scaffolds. Due to the performance limitations of single materials, functional composite biomaterials have attracted great attention as tools to improve the effectiveness of biological scaffolds for tissue repair. In recent years, metal-organic frameworks (MOFs) have shown great promise for application in tissue engineering because of their high specific surface area, high porosity, high biocompatibility, appropriate environmental sensitivities and other advantages. This review introduces methods for the construction of MOFs-based functional composite scaffolds and describes the specific functions and mechanisms of MOFs in repairing damaged tissue. The latest MOFs-based functional composites and their applications in different tissues are discussed. Finally, the challenges and future prospects of using MOFs-based composites in tissue engineering are summarized. The aim of this review is to show the great potential of MOFs-based functional composite materials in the field of tissue engineering and to stimulate further innovation in this promising area.

Recent progress in functional metal-organic frameworks for bio-medical application

Metal-organic frameworks (MOFs) have a high specific surface area, adjustable pores and can be used to obtain functional porous materials with diverse and well-ordered structures through coordination and self-assembly, which has intrigued wide interest in a broad range of disciplines. In the arena of biomedical engineering, the functionalized modification of MOFs has produced drug carriers with excellent dispersion and functionalities such as target delivery and response release, with promising applications in bio-detection, disease therapy, tissue healing, and other areas. This review summarizes the present state of research on the functionalization of MOFs by physical binding or chemical cross-linking of small molecules, polymers, biomacromolecules, and hydrogels and evaluates the role and approach of MOFs functionalization in boosting the reactivity of materials. On this basis, research on the application of functionalized MOFs composites in biomedical engineering fields such as drug delivery, tissue repair, disease treatment, bio-detection and imaging is surveyed, and the development trend and application prospects of functionalized MOFs as an important new class of biomedical materials in the biomedical field are anticipated, which may provide some inspiration and reference for further development of MOF for bio-medical applications.

Lanthanide complexes facilitate wound healing by promoting fibroblast viability, migration and M2 macrophage polarization

A tridentate ligand LH3 ((2-hydroxy-3-methoxybenzylidene)-2-(hydroxyimino)propanehydrazide) comprising o-vanillin, hydrazone and oxime donor groups has been employed to prepare a series of tetranuclear Ln(III) complexes. The reaction of ligand LH3 with Ln(NO3)3 [Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er] in MeOH yielded Ln4(LH)6(MeOH)2 (Ln = Sm(1), Eu(2), Gd(3), Tb(4), Ho (6) and Er (7))] whereas the corresponding reaction with Dy(NO3)3 afforded Dy4(LH)4(LH2)2(OH)2 (5). All complexes were characterized by various analytical techniques including single crystal X-ray diffraction, IR spectroscopy, UV-Vis spectroscopy, and elemental analysis. To investigate the potential of these lanthanide complexes for wound healing applications, their effects on fibroblast viability, migration, and M2 macrophage polarization were evaluated. The cytotoxicity assessment revealed that complexes 2(Eu), 4(Tb), 5(Dy), and 7(Er) significantly enhanced fibroblast viability compared to the negative control (NC). In vitro wound healing assay demonstrated that complexes 2(Eu) and 7(Eu) substantially promoted fibroblast migration compared to the NC. Moreover, complex 2(Eu) exhibited significant anti-inflammatory effects by reducing the phagocytic ability of lipopolysaccharide (LPS)-stimulated macrophage cells and attenuating nitric oxide (NO) production. In conclusion, among the series of complexes tested, complex 2(Eu) displayed the most potent anti-inflammatory effect on macrophage cells, while simultaneously promoting fibroblast viability and migration. This unique combination of properties renders complex 2 (Eu) highly promising for wound healing applications.

ROS-responsive hydrogels with spatiotemporally sequential delivery of antibacterial and anti-inflammatory drugs for the repair of MRSA-infected wounds

For the treatment of MRSA-infected wounds, the spatiotemporally sequential delivery of antibacterial and anti-inflammatory drugs is a promising strategy. In this study, ROS-responsive HA-PBA/PVA (HPA) hydrogel was prepared by phenylborate ester bond cross-linking between hyaluronic acid-grafted 3-amino phenylboronic acid (HA-PBA) and polyvinyl alcohol (PVA) to achieve spatiotemporally controlled release of two kinds of drug to treat MRSA-infected wound. The hydrophilic antibiotic moxifloxacin (M) was directly loaded in the hydrogel. And hydrophobic curcumin (Cur) with anti-inflammatory function was first mixed with Pluronic F127 (PF) to form Cur-encapsulated PF micelles (Cur-PF), and then loaded into the HPA hydrogel. Due to the different hydrophilic and hydrophobic nature of moxifloxacin and Cur and their different existing forms in the HPA hydrogel, the final HPA/M&Cur-PF hydrogel can achieve different spatiotemporally sequential delivery of the two drugs. In addition, the swelling, degradation, self-healing, antibacterial, anti-inflammatory, antioxidant property, and biocompatibility of hydrogels were tested. Finally, in the MRSA-infected mouse skin wound, the hydrogel-treated group showed faster wound closure, less inflammation and more collagen deposition. Immunofluorescence experiments further confirmed that the hydrogel promoted better repair by reducing inflammation (TNF-α) and promoting vascular (VEGF) regeneration. In conclusion, this HPA/M&Cur-PF hydrogel that can spatiotemporally sequential deliver antibacterial and anti-inflammatory drugs showed great potential for the repair of MRSA-infected skin wounds.

Metallic elements combine with herbal compounds upload in microneedles to promote wound healing: a review

Wound healing is a dynamic and complex restorative process, and traditional dressings reduce their therapeutic effectiveness due to the accumulation of drugs in the cuticle. As a novel drug delivery system, microneedles (MNs) can overcome the defect and deliver drugs to the deeper layers of the skin. As the core of the microneedle system, loaded drugs exert a significant influence on the therapeutic efficacy of MNs. Metallic elements and herbal compounds have been widely used in wound treatment for their ability to accelerate the healing process. Metallic elements primarily serve as antimicrobial agents and facilitate the enhancement of cell proliferation. Whereas various herbal compounds act on different targets in the inflammatory, proliferative, and remodeling phases of wound healing. The interaction between the two drugs forms nanoparticles (NPs) and metal-organic frameworks (MOFs), reducing the toxicity of the metallic elements and increasing the therapeutic effect. This article summarizes recent trends in the development of MNs made of metallic elements and herbal compounds for wound healing, describes their advantages in wound treatment, and provides a reference for the development of future MNs.

Drug release and solubility properties of two zeolitic metal-organic frameworks influenced by their hydrophobicity/hydrophilicity

Metal-organic frameworks (MOFs) have shown significant potential for drug delivery applications. However, there remains a scarcity of comprehensive research addressing the influence of surface properties of MOFs on drug release kinetics and drug solubility. This study focuses on examining the influence of MOFs hydrophilicity and hydrophobicity on the controlled release and solubility of drugs. To achieve this, we prepared drug-loaded nanoparticles through in situ synthesis and created a drug-MOF co-amorphous system using the ball milling technique. Under neutral conditions, the hydrophilic MOF-based drug delivery system demonstrated a comparatively slower drug release profile than its hydrophobic counterpart. This observation suggests that the hydrophilic system holds promise in mitigating drug side effects by enabling improved control over drug release. The implementation of hydrophobic MOFs in co-amorphous systems yields a more pronounced effect on enhancing solubility compared to hydrophilic MOFs. This study offers valuable insights for achieving optimal drug release kinetics and solubility by delicately manipulating surface properties of MOFs.

Bibliometric and visualized analysis of metal-organic frameworks in biomedical application

Background: Metal-organic frameworks (MOFs) are hybrid materials composed of metal ions or clusters and organic ligands that spontaneously assemble via coordination bonds to create intramolecular pores, which have recently been widely used in biomedicine due to their porosity, structural, and functional diversity. They are used in biomedical applications, including biosensing, drug delivery, bioimaging, and antimicrobial activities. Our study aims to provide scholars with a comprehensive overview of the research situations, trends, and hotspots in biomedical applications of MOFs through a bibliometric analysis of publications from 2002 to 2022. Methods: On 19 January 2023, the Web of Science Core Collection was searched to review and analyze MOFs applications in the biomedical field. A total of 3,408 studies published between 2002 and 2022 were retrieved and examined, with information such as publication year, country/region, institution, author, journal, references, and keywords. Research hotspots were extracted and analyzed using the Bibliometrix R-package, VOSviewer, and CiteSpace. Results: We showed that researchers from 72 countries published articles on MOFs in biomedical applications, with China producing the most publications. The Chinese Academy of Science was the most prolific contributor to these publications among 2,209 institutions that made contributions. Reference co-citation analysis classifies references into 8 clusters: synergistic cancer therapy, efficient photodynamic therapy, metal-organic framework encapsulation, selective fluorescence, luminescent probes, drug delivery, enhanced photodynamic therapy, and metal-organic framework-based nanozymes. Keyword co-occurrence analysis divided keywords into 6 clusters: biosensors, photodynamic therapy, drug delivery, cancer therapy and bioimaging, nanoparticles, and antibacterial applications. Research frontier keywords were represented by chemodynamic therapy (2020-2022) and hydrogen peroxide (2020-2022). Conclusion: Using bibliometric methods and manual review, this review provides a systematic overview of research on MOFs in biomedical applications, filling an existing gap. The burst keyword analysis revealed that chemodynamic therapy and hydrogen peroxide are the prominent research frontiers and hot spots. MOFs can catalyze Fenton or Fenton-like reactions to generate hydroxyl radicals, making them promising materials for chemodynamic therapy. MOF-based biosensors can detect hydrogen peroxide in various biological samples for diagnosing diseases. MOFs have a wide range of research prospects for biomedical applications.

Photodynamic Alginate Zn-MOF Thermosensitive Hydrogel for Accelerated Healing of Infected Wounds

Antibiotic resistance reduces the effectiveness of infected wound healing, and it is necessary to develop a new strategy to promote infected wound healing without using antibiotics. Here, we develop a Chlorin e6 (Ce6)-loaded zinc-metal-organic framework (MOF) thermosensitive hydrogel (Ce6@MOF-Gel) based on alginate and poly(propylene glycol) 407, which enhances antibacterial effects and promotes infected wound healing by a novel strategy of combining zinc-MOF with photodynamic therapy (PDT). Zinc-MOF can realize acid-responsive release of Ce6 and improve antibacterial performance without drug resistance by destroying the integrity of bacterial cell membranes and enhancing the production of bacterial reactive oxygen species (ROS). Additionally, Ce6@MOF-Gel enhances the stability, solubility, and photodynamic properties of Ce6. More importantly, Ce6@MOF-Gel reduces inflammation and promotes collagen deposition and re-epithelialization to facilitate infected wound healing. Collectively, the photodynamic MOF-based hydrogel provides a new, efficient, and safe way for accelerated healing of infected wounds.

Engineering Metal-Organic-Framework (MOF)-Based Membranes for Gas and Liquid Separation

Separation is one of the most energy-intensive processes in the chemical industry, and membrane-based separation technology contributes significantly to energy conservation and emission reduction. Additionally, metal-organic framework (MOF) materials have been widely investigated and have been found to have enormous potential in membrane separation due to their uniform pore size and high designability. Notably, pure MOF films and MOF mixed matrix membranes (MMMs) are the core of the "next generation" MOF materials. However, there are some tough issues with MOF-based membranes that affect separation performance. For pure MOF membranes, problems such as framework flexibility, defects, and grain orientation need to be addressed. Meanwhile, there still exist bottlenecks for MMMs such as MOF aggregation, plasticization and aging of the polymer matrix, poor interface compatibility, etc. Herein, corresponding methods are introduced to solve these problems, including inhibiting framework flexibility, regulating synthesis conditions, and enhancing the interaction between MOF and substrate. A series of high-quality MOF-based membranes have been obtained based on these techniques. Overall, these membranes revealed desired separation performance in both gas separation (e.g., CO₂, H₂, and olefin/paraffin) and liquid separation (e.g., water purification, organic solvent nanofiltration, and chiral separation).

Dual-Functional Nanoplatform Based on Bimetallic Metal-Organic Frameworks for Synergistic Starvation and Chemodynamic Therapy

Tumor microenvironment (TME)-responsive chemodynamic therapy (CDT) mediated by nanozymes has been extensively studied in oral squamous cell carcinoma. However, the low catalytic efficiency due to insufficient H₂O₂ in the TME is still a major challenge for its clinical translation. Herein, we present an antitumor nanoplatform based on a Mn-Co organometallic framework material (MnCoMOF), which shows peroxidase-like (POD-like) activity, loaded with glucose oxidase (GOx@MnCoMOF), demonstrating the ability of H₂O₂ self-supply and H₂O₂ conversion to toxic hydroxyl radicals. The encapsulated GOx efficiently catalyzes glucose into gluconic acid and H₂O₂ at the tumor site, which can cut off the energy supply to inhibit tumor growth and produce a large amount of H₂O₂ and acid to compensate for their lack in the tumor microenvironment. The POD-like activity of MnCoMOF can convert H₂O₂ into hydroxyl radicals and eliminate tumor cells. The nanoplatform exhibits enhanced tumor cell cytotoxicity in a high-glucose medium compared with a low-glucose medium, illustrating sufficient generation of H₂O₂ from glucose by GOx. The in vivo results indicate that GOx@MnCoMOF has excellent antitumor efficacy and can remodel the immune-suppressive tumor microenvironment. In conclusion, the GOx@MnCoMOF nanoplatform possesses dual enzymatic activities, i.e., POD-like and glucose oxidase, to achieve improved tumor-suppressive efficiency through synergistic starvation and chemodynamic therapy, thus providing a new strategy for the clinical treatment of oral cancer.

Biomaterials releasing drug responsively to promote wound healing via regulation of pathological microenvironment

Wound healing is characterized by complex, orchestrated, spatiotemporal dynamic processes. Recent findings demonstrated suitable local microenvironments were necessities for wound healing. Wound microenvironments include various biological, biochemical and physical factors, which are produced and regulated by endogenous biomediators, exogenous drugs, and external environment. Successful drug delivery to wound is complicated, and need to overcome the destroyed blood supply, persistent inflammation and enzymes, spatiotemporal requirements of special supplements, and easy deactivation of drugs. Triggered by various factors from wound microenvironment itself or external elements, stimuli-responsive biomaterials have tremendous advantages of precise drug delivery and release. Here, we discuss recent advances of stimuli-responsive biomaterials to regulate local microenvironments during wound healing, emphasizing on the design and application of different biomaterials which respond to wound biological/biochemical microenvironments (ROS, pH, enzymes, glucose and glutathione), physical microenvironments (mechanical force, temperature, light, ultrasound, magnetic and electric field), and the combination modes. Moreover, several novel promising drug carriers (microbiota, metal-organic frameworks and microneedles) are also discussed.

Comparative Analysis of Physical and Chemical Properties of Differently Obtained Zn-Methionine Chelate with Proved Antibiofilm Properties (Part II)

The previously demonstrated activity of aqueous solutions of methionine and zinc salts against biofilms of uropathogenic bacteria prompted us to investigate the structure and properties of zinc methionine complex obtained from such solutions. The paper presents the analysis results of zinc coordination complexes with methionine obtained by synthesis (0.034 mol of L-methionine, 0.034 mol of NaOH, 40 mL of H₂O, 0.017 mol ZnSO₄, 60 °C) and simple crystallization from water solution (25 mL of a solution containing 134 mmol/L L-methionine, 67 mmol/L ZnSO₄, pH = 5.74, I = 0.37 mmol/L, crystallization at room temperature during more than two weeks). IR spectral analysis and X-ray diffraction showed the structural similarity of the substances to each other, in agreement with the data described in the literature. DSC confirmed the formation of a thermally stable (in the range from -30 °C to 180 °C) chelate compound in both cases and indicated the possible retention of the polymorphic two-dimensional structure inherent in L-methionine with the temperature of phase transition 320 K. The crystallized complex had better solubility in water (100 to 1000 mL per 1.0 g) contra the synthesized analog, which was practically insoluble (more than 10 000 mL per 1.0 g). The results of the solubility assessment, supplemented by the results of the dispersion analysis of solutions by the dynamic light scattering method indicated the formation of zinc-containing nanoparticles (80 nm) in a saturated water solution of a crystallized substance, suggesting the crystallized substance may have higher bioavailability. We predicted a possibility of the equivalent existence of optically active cis and trans isomers in methionine-zinc solutions by the close values of formation enthalpy (-655 kJ/mol and -657 kJ/mol for cis and trans forms, respectively) and also illustrated by the polarimetry measurement results (∆α = 0.4°, pH = 5.74, C(Met) = 134 mmol/L; the concentration of metal ion gradually increased from 0 to 134 mmol/L). The obtained results allowed us to conclude that the compound isolated from the solution is a zinc-methionine chelate with the presence of sulfate groups and underline the role of the synthesis route for the biopharmaceutical characteristics of the resulting substance. We provided some quality indicators that it may be possible to include in the pharmacopeia monographs.

Natural Morin-Based Metal Organic Framework Nanoenzymes Modulate Articular Cavity Microenvironment to Alleviate Osteoarthritis

Osteoarthritis (OA) is always characterized as excessive reactive oxygen species (ROS) inside articular cavity. Mimicking natural metalloenzymes with metal ions as the active centers, stable metal organic framework (MOF) formed by natural polyphenols and metal ions shows great potential in alleviating inflammatory diseases. Herein, a series of novel copper-morin-based MOF (CuMHs) with different molar ratios of Cu²⁺ and MH were employed to serve as ROS scavengers for OA therapy. As a result, CuMHs exhibited enhanced dispersion in aqueous solution, improved biocompatibility, and efficient ROS-scavenging ability compared to MH. On the basis of H₂O₂-stimulated chondrocytes, intracellular ROS levels were efficiently declined and cell death was prevented after treated by Cu₆MH (Cu²⁺ and MH molar ratio of 6:1). Meanwhile, Cu₆MH also exhibited efficient antioxidant and anti-inflammation function by down-regulating the expression of IL6, MMP13, and MMP3, and up-regulating cartilage specific gene expression as well. Importantly, Cu₆MH could repair mitochondrial function by increasing mitochondrial membrane potential, reducing the accumulation of calcium ions, as well as promoting ATP content production. In OA joint model, intra-articular (IA) injected Cu₆MH suppressed the progression of OA. It endowed that Cu₆MH might be promising nanoenzymes for the prevention and treatment of various inflammatory diseases.

Engineering functional natural polymer-based nanocomposite hydrogels for wound healing

Skin injury occurs due to acute trauma, chronic trauma, infection, and surgical intervention, which can result in severe dysfunction and even death in humans. Therefore, clinical intervention is critical for the treatment of skin wounds. One idealized method is to use wound dressings to protect skin wounds and promote wound healing. Among these wound dressings, nanocomposite natural polymer hydrogels (NNPHs) are multifunctional wound dressings for wound healing. The combination of nanomaterials and natural polymer hydrogels avoids the shortcomings of a single component. Moreover, nanomaterials could provide improved antibacterial, anti-inflammatory, antioxidant, stimuli-responsive, electrically conductive and mechanical properties of hydrogels to accelerate wound healing. This review focuses on recent advancements in NNPHs for skin wound healing and repair. Initially, the functions and requirements of NNPHs as wound dressings were introduced. Second, the design, preparation and capacities of representative NNPHs are classified based on their nanomaterial. Third, skin wound repair applications of NNPHs have been summarized based on the types of wounds. Finally, the potential issues of NNPHs are discussed, and future research is proposed to prepare idealized multifunctional NNPHs for skin tissue regeneration.

Zinc and Zinc Transporters in Dermatology

Zinc is an important trace mineral in the human body and a daily intake of zinc is required to maintain a healthy status. Over the past decades, zinc has been used in formulating topical and systemic therapies for various skin disorders owing to its wound healing and antimicrobial properties. Zinc transporters play a major role in maintaining the integrity of the integumentary system by controlling zinc homeostasis within dermal layers. Mutations and abnormal function of zinc-transporting proteins can lead to disease development, such as spondylocheirodysplastic Ehlers-Danlos syndrome (SCD-EDS) and acrodermatitis enteropathica (AE) which can be fatal if left untreated. This review discusses the layers of the skin, the importance of zinc and zinc transporters in each layer, and the various skin disorders caused by zinc deficiency, in addition to zinc-containing compounds used for treating different skin disorders and skin protection.

Recent advances in regenerative biomaterials

Nowadays, biomaterials have evolved from the inert supports or functional substitutes to the bioactive materials able to trigger or promote the regenerative potential of tissues. The interdisciplinary progress has broadened the definition of 'biomaterials', and a typical new insight is the concept of tissue induction biomaterials. The term 'regenerative biomaterials' and thus the contents of this article are relevant to yet beyond tissue induction biomaterials. This review summarizes the recent progress of medical materials including metals, ceramics, hydrogels, other polymers and bio-derived materials. As the application aspects are concerned, this article introduces regenerative biomaterials for bone and cartilage regeneration, cardiovascular repair, 3D bioprinting, wound healing and medical cosmetology. Cell-biomaterial interactions are highlighted. Since the global pandemic of coronavirus disease 2019, the review particularly mentions biomaterials for public health emergency. In the last section, perspectives are suggested: (i) creation of new materials is the source of innovation; (ii) modification of existing materials is an effective strategy for performance improvement; (iii) biomaterial degradation and tissue regeneration are required to be harmonious with each other; (iv) host responses can significantly influence the clinical outcomes; (v) the long-term outcomes should be paid more attention to; (vi) the noninvasive approaches for monitoring in vivo dynamic evolution are required to be developed; (vii) public health emergencies call for more research and development of biomaterials; and (viii) clinical translation needs to be pushed forward in a full-chain way. In the future, more new insights are expected to be shed into the brilliant field-regenerative biomaterials.

ε-Polylysine-Based Macromolecules with Catalase-Like Activity to Accelerate Wound Healing by Clearing Bacteria and Attenuating Inflammatory Response

Wound healing has remained a critical challenge due to its susceptibility to bacterial infection and the unique biological inflammatory response. Safe and effective therapeutics are still lacking. Biodegradable macromolecules (ε-polylysine-g-ferrocene, EPL-g-Fc) were developed to accelerate wound healing by combating bacterial infection and attenuating inflammatory responses. The biodegradable macromolecules were prepared via a Schiff-based reaction between ferrocene carboxaldehyde (Fc) and ε-polylysine (EPL). Through the synergistic combination of positive-charged EPL and π-π stacked Fc, the macromolecules possess excellent antibacterial activities. EPL-g-Fc with catalase-like activity could modulate the oxidative microenvironment in mammalian cells and zebrafish by catalyzing H₂O₂ into H₂O and O₂. EPL-g-Fc could alleviate inflammatory response in vitro. Furthermore, the macromolecules could accelerate bacteria-infected wound healing in vivo. This work provides a versatile strategy for repairing bacteria-infected wounds by eliminating bacteria, modulating oxidative microenvironment, and alleviating inflammatory response.

Possible Synergies of Nanomaterial-Assisted Tissue Regeneration in Plasma Medicine: Mechanisms and Safety Concerns

Cold atmospheric plasma and nanomedicine originally emerged as individual domains, but are increasingly applied in combination with each other. Most research is performed in the context of cancer treatment, with only little focus yet on the possible synergies. Many questions remain on the potential of this promising hybrid technology, particularly regarding regenerative medicine and tissue engineering. In this perspective article, we therefore start from the fundamental mechanisms in the individual technologies, in order to envision possible synergies for wound healing and tissue recovery, as well as research strategies to discover and optimize them. Among these strategies, we demonstrate how cold plasmas and nanomaterials can enhance each other's strengths and overcome each other's limitations. The parallels with cancer research, biotechnology and plasma surface modification further serve as inspiration for the envisioned synergies in tissue regeneration. The discovery and optimization of synergies may also be realized based on a profound understanding of the underlying redox- and field-related biological processes. Finally, we emphasize the toxicity concerns in plasma and nanomedicine, which may be partly remediated by their combination, but also partly amplified. A widespread use of standardized protocols and materials is therefore strongly recommended, to ensure both a fast and safe clinical implementation.

Application of Metal–Organic Framework in Diagnosis and Treatment of Diabetes

Diabetes-related chronic wounds are often accompanied by a poor wound-healing environment such as high glucose, recurrent infections, and inflammation, and standard wound treatments are fairly limited in their ability to heal these wounds. Metal–organic frameworks (MOFs) have been developed to improve therapeutic outcomes due to their ease of engineering, surface functionalization, and therapeutic properties. In this review, we summarize the different synthesis methods of MOFs and conduct a comprehensive review of the latest research progress of MOFs in the treatment of diabetes and its wounds. State-of-the-art in vivo oral hypoglycemic strategies and the in vitro diagnosis of diabetes are enumerated and different antimicrobial strategies (including physical contact, oxidative stress, photothermal, and related ions or ligands) and provascular strategies for the treatment of diabetic wounds are compared. It focuses on the connections and differences between different applications of MOFs as well as possible directions for improvement. Finally, the potential toxicity of MOFs is also an issue that we cannot ignore.