Near-Infrared Light-Mediated Cyclodextrin Metal-Organic Frameworks for Synergistic Antibacterial and Anti-Biofilm Therapies

Ultra-small gold nanoparticles embedded cyclodextrin metal-organic framework composite membrane to achieve antibacterial and humidity-responsive functions

Cyclodextrin metal-organic framework (CD-MOF) is an edible and porous material that can serve as a template for synthesizing small-sized metal nanoparticles. However, its highly hydrophilic nature has limited its wider application. Herein, ultra-small gold nanoparticles (U-AuNPs) were loaded into CD-MOF to produce a composite material Au@CD-MOF. The CD-MOF was utilized as a template to control the size of the AuNPs. The synthesized Au@CD-MOF was easily dispersible in aqueous medium and its released U-AuNPs exhibited effective water dispersion stability within 120 days. Additionally, compared to gold nanoparticles prepared using traditional methods (T-AuNPs), the U-AuNPs exhibited superior antibacterial properties. Furthermore, hydrophilic Au@CD-MOF was incorporated into a hydrophobic polydimethylsiloxane (PDMS) matrix (Au@CD-MOF/PDMS) to achieve a humidity-responsive antibacterial function. The composite membrane exhibited remarkable responsiveness to humidity, showing almost no release of U-AuNPs at 0 % humidity. However, it exhibited approximately 89 % release within 1 h, and complete release of U-AuNPs was observed within 4 h under 100 % humidity. These findings highlight the successful preparation of a humidity-responsive antibacterial composite membrane, which has great potential applications in various scenarios, particularly in the field of antibacterial food packaging.

Engineering mesoporous polydopamine-based potentiate STING pathway activation for advanced anti-biofilm therapy

The biofilm-induced "relatively immune-compromised zone" creates an immunosuppressive microenvironment that is a significant contributor to refractory infections in orthopedic endophytes. Consequently, the manipulation of immune cells to co-inhibit or co-activate signaling represents a crucial strategy for the management of biofilm. This study reports the incorporation of Mn2+ into mesoporous dopamine nanoparticles (Mnp) containing the stimulator of interferon genes (STING) pathway activator cGAMP (Mncp), and outer wrapping by M1-like macrophage cell membrane (m-Mncp). The cell membrane enhances the material's targeting ability for biofilm, allowing it to accumulate locally at the infectious focus. Furthermore, m-Mncp mechanically disrupts the biofilm through photothermal therapy and induces antigen exposure through photodynamic therapy-generated reactive oxygen species (ROS). Importantly, the modulation of immunosuppression and immune activation results in the augmentation of antigen-presenting cells (APCs) and the commencement of antigen presentation, thereby inducing biofilm-specific humoral immunity and memory responses. Additionally, this approach effectively suppresses the activation of myeloid-derived suppressor cells (MDSCs) while simultaneously boosting the activity of T cells. Our study showcases the efficacy of utilizing m-Mncp immunotherapy in conjunction with photothermal and photodynamic therapy to effectively mitigate residual and recurrent infections following the extraction of infected implants. As such, this research presents a viable alternative to traditional antibiotic treatments for biofilm that are challenging to manage.

Enhanced antibacterial activity of a novel silver-based metal organic framework towards multidrug-resistant Klebsiella pneumonia

The growth and spread of multidrug-resistant bacterial species, such as Klebsiella pneumoniae, pose a serious threat to human health and require the development of innovative antibacterial agents. The search for an acceptable, safe, and efficient antibacterial is a matter of significant concern. In the present work, silver-based metal-organic frameworks (Ag-MOFs) showed efficient antibacterial activity against multidrug-resistant K. pneumoniae (KBP 11) with a minimum inhibitory concentration and minimum bactericidal concentration of 10 μg mL-1. Moreover, the Ag-MOF showed enhanced antibacterial activity compared to silver ions and silver nanoparticles. Our experimental investigation showed that the antibacterial efficacy is attributed to the production of reactive oxygen species and the release of cellular constituents, such as K+ ions and proteins. The MOF scaffold enhances the stability and controlled release of silver ions, enabling sustained antibacterial activity and minimizing the risk of bacterial resistance development. Additionally, the MOF class, due to the high surface area and porous nature, enhances the transfer of bacteria into and on the surface of the MOF.

Current strategies for monitoring and controlling bacterial biofilm formation on medical surfaces

Biofilms, intricate microbial communities that attach to surfaces, especially medical devices, form an exopolysaccharide matrix, which enables bacteria to resist environmental pressures and conventional antimicrobial agents, leading to the emergence of multi-drug resistance. Biofilm-related infections associated with medical devices are a significant public health threat, compromising device performance. Therefore, developing effective methods for supervising and managing biofilm growth is imperative. This in-depth review presents a systematic overview of strategies for monitoring and controlling bacterial biofilms. We first outline the biofilm creation process and its regulatory mechanisms. The discussion then progresses to advancements in biosensors for biofilm detection and diverse treatment strategies. Lastly, this review examines the obstacles and new perspectives associated with this domain to facilitate the advancement of innovative monitoring and control solutions. These advancements are vital in combating the spread of multi drug-resistant bacteria and mitigating public health risks associated with infections from biofilm formation on medical instruments.

Cell Membrane Engineered Polypeptide Nanonets Mimicking Macrophage Aggregates for Enhanced Antibacterial Treatment

Drug-resistant bacterial infections and their lipopolysaccharide-related inflammatory complications continue to pose significant challenges in traditional treatments. Inspired by the rapid initiation of resident macrophages to form aggregates for efficient antibacterial action, this study proposes a multifunctional and enhanced antibacterial strategy through the construction of novel biomimetic cell membrane polypeptide nanonets (R-DPB-TA-Ce). The design involves the fusion of end-terminal lipidated polypeptides containing side-chain cationic boronic acid groups (DNPLBA) with cell membrane intercalation engineering (R-DPB), followed by coordination with the tannic acid-cerium complex (TA-Ce) to assemble into a biomimetic nanonet through boronic acid-polyphenol-metal ion interactions. In addition to the ability of RAW 264.7 macrophages cell membrane components' (R) ability to neutralize lipopolysaccharide (LPS), R-DPB-TA-Ce demonstrated enhanced capture of bacteria and its LPS, leveraging nanoconfinement-enhanced multiple interactions based on the boronic acid-polyphenol nanonets skeleton combined with polysaccharide. Utilizing these advantages, indocyanine green (ICG) is further employed as a model drug for delivery, showcasing the exceptional treatment effect of R-DPB-TA-Ce as a new biomimetic assembled drug delivery system in antibacterial, anti-inflammatory, and wound healing promotion. Thus, this strategy of mimicking macrophage aggregates is anticipated to be further applicable to various types of cell membrane engineering for enhanced antibacterial treatment.

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.

Thrombotic microenvironment responsive crosslinking cyclodextrin metal-organic framework nanocarriers for precise targeting and thrombolysis

Global public health is seriously threatened by thrombotic disorders because of their high rates of mortality and disability. Most thrombolytic agents, especially protein-based pharmaceuticals, have a short half-life in circulation, reducing their effectiveness in thrombolysis. The creation of an intelligent drug delivery system that delivers medication precisely and releases it under regulated conditions at nearby thrombus sites is essential for effective thrombolysis. In this article, we present a unique medication delivery system (MCRUA) that selectively targets platelets and releases drugs by stimulation from the thrombus' microenvironment. The thrombolytic enzyme urokinase-type plasminogen-activator (uPA) and the anti-inflammatory medication Aspirin (acetylsalicylic acid, ASA) are both loaded onto pH-sensitive CaCO3/cyclodextrin crosslinking metal-organic frameworks (MC) that make up the MCRUA system. c(RGD) is functionalized on the surface of MC, which is functionalized by RGD to an esterification reaction. Additionally, the thrombus site's acidic microenvironment causes MCRUA to disintegrate to release uPA for thrombolysis and aiding in vessel recanalization. Moreover, cyclodextrin-encapsulated ASA enables the treatment of the inflammatory environment within the thrombus, enhancing the antiplatelet aggregation effects and promoting cooperative thrombolysis therapy. When used for thrombotic disorders, our drug delivery system (MCRUA) promotes thrombolysis, suppresses rethrombosis, and enhances biosafety with fewer hemorrhagic side effects.

Metal-Organic Framework Based Mucoadhesive Nanodrugs for Multifunction Helicobacter Pylori Targeted Eradication, Inflammation Regulation and Gut Flora Protection

The prevalence of drug-resistant bacteria presents a significant challenge to the antibiotic treatment of Helicobacter pylori (H. pylori), while traditional antimicrobial agents often suffer from shortcomings such as poor gastric retention, inadequate alleviation of inflammation, and significant adverse effects on the gut microbiota. Here, a selenized chitosan (CS-Se) modified bismuth-based metal-organic framework (Bi-MOF@CS-Se) nanodrug is reported that can target mucin through the charge interaction of the outer CS-Se layer to achieve mucosal adhesion and gastric retention. Additionally, the Bi-MOF@CS-Se can respond to gastric acid and pepsin degradation, and the exposed Bi-MOF exhibits excellent antibacterial properties against standard H. pylori as well as clinical antibiotic-resistant strains. Remarkably, the Bi-MOF@CS-Se effectively alleviates inflammation and excessive oxidative stress by regulating the expression of inflammatory factors and the production of reactive oxygen species (ROS), thereby exerting therapeutic effects against H. pylori infection. Importantly, this Bi-MOF@CS-Se nanodrug does not affect the homeostasis of gut microbiota, providing a promising strategy for efficient and safe treatment of H. pylori infection.

Precise healing of oral and maxillofacial wounds: tissue engineering strategies and their associated mechanisms

Precise healing of wounds in the oral and maxillofacial regions is usually achieved by targeting the entire healing process. The rich blood circulation in the oral and maxillofacial regions promotes the rapid healing of wounds through the action of various growth factors. Correspondingly, their tissue engineering can aid in preventing wound infections, accelerate angiogenesis, and enhance the proliferation and migration of tissue cells during wound healing. Recent years, have witnessed an increase in the number of researchers focusing on tissue engineering, particularly for precise wound healing. In this context, hydrogels, which possess a soft viscoelastic nature and demonstrate exceptional biocompatibility and biodegradability, have emerged as the current research hotspot. Additionally, nanofibers, films, and foam sponges have been explored as some of the most viable materials for wound healing, with noted advantages and drawbacks. Accordingly, future research is highly likely to explore the application of these materials harboring enhanced mechanical properties, reduced susceptibility to external mechanical disturbances, and commendable water absorption and non-expansion attributes, for superior wound healing.

Metal-Phenolic Nanocapsules with Photothermal Antibacterial and Ros Scavenging Ability for Diabetic Wound Healing

The presence of bacteria in diabetic wounds not only leads to the formation of biofilms but also triggers oxidative stress and inflammatory responses, which hinder the wound-healing process. Therefore, it is imperative to formulate a comprehensive strategy that can proficiently eliminate bacteria and enhance the wound microenvironment. Herein, this work develops multifunctional metal-phenolic nanozymes (TA-Fe/Cu nanocapsules), wherein the one-pot coordination of tannic acid (TA)and Fe3+/Cu2+ using a self-sacrificial template afforded hollow nanoparticles (NPs) with exceptional photothermal and reactive oxygen species scavenging capabilities. After photothermal disruption of the biofilms, TA-Fe/Cu NPs autonomously capture bacteria through hydrogen bonding interactions with peptidoglycans (the bacterial cell wall component), ultimately bolstering the bactericidal efficacy. Furthermore, these NPs exhibit peroxidase-like enzymatic activity, efficiently eliminating surplus hydrogen peroxide in the vicinity of the wound and mitigating inflammatory responses. As the wound transitions into the remodeling phase, the presence of Cu2+ stimulates vascular migration and regeneration, expediting the wound-healing process. This study innovatively devises a minimalist approach to synthesize multifunctional metal-phenolic nanozymes integrating potent photothermal antibacterial activity, bacterial capture, anti-inflammatory, and angiogenesis properties, showcasing their great potential for diabetic wound treatment.

pH-responsive on-demand release of eugenol from metal-organic frameworks for synergistic bacterial killing

Bacterial infections are a big challenge in clinical treatment, making it urgent to develop innovative antibacterial systems and therapies to combat bacterial infections. In this study, we developed a novel MOF-based synergistic antibacterial system (Eu@B-UiO-66/Zn) by loading a natural antibacterial substance (eugenol) with hierarchically porous MOF B-UiO-66 as a carrier and further complexing it with divalent zinc ions. Results indicate that the system achieved a controlled release of eugenol under pH responsive stimulation, with the complexation ability of eugenol and Zn2+ ions as a switch. Due to the destruction of a coordination bond between eugenol and Zn2+ ions by an acidic medium, the release of eugenol loaded in Eu@B-UiO-66/Zn reached 80% at pH 5.8, which was significantly higher than that under pH 8.0 (51%). Moreover, the inhibitory effect of Eu@B-UiO-66/Zn against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) after 24 h was 96.4% and 99.7%, respectively, owing to the synergistic antibacterial effect of eugenol and Zn2+ ions, which was significantly stronger than free eugenol and Eu@B-UiO-66. We hope that this strategy for constructing responsive MOF-based antibacterial carriers could have potential possibilities for the application of MOF materials in antibacterial fields.

Arginine-Enhanced Antimicrobial Activity of Nanozymes against Gram-Negative Bacteria

The continuous reduction of clinically available antibiotics has made it imperative to exploit more effective antimicrobial therapies, especially for difficult-to-treat Gram-negative pathogens. Herein, it is shown that the combination of an antimicrobial nanozyme with the clinically compatible basic amino acid L-arginine affords a potent treatment for infections with Gram-negative pathogens. In particular, the antimicrobial activity of the antimicrobial nanozyme is dramatically increased by ≈1000-fold after L-arginine stimulation. Specifically, the combination therapy enhances bacterial outer and inner membrane permeability and promotes intracellular reactive oxygen species (ROS) generation. Moreover, the metabolomic and transcriptomic results reveal that combination treatment leads to the increased ROS-mediated damage by inhibiting the tricarboxylic acid cycle and oxidative phosphorylation, thereby inducing an imbalance of the antioxidant and oxidant systems. Importantly, L-arginine dramatically significantly accelerates the healing of infected wounds in mouse models of multidrug-resistant peritonitis-sepsis and skin wound infection. Overall, this work demonstrates a novel synergistic antibacterial strategy by combining the antimicrobial nanozymes with L-arginine, which substantively facilitates the nanozyme-mediated killing of pathogens by promoting ROS production.

Near infrared II excitation nanoplatform for photothermal/chemodynamic/antibiotic synergistic therapy combating bacterial biofilm infections

Drug-resistant bacterial biofilm infections (BBIs) are refractory to elimination. Near-infrared-II photothermal therapy (NIR-II PTT) and chemodynamic therapy (CDT) are emerging antibiofilm approaches because of the heavy damage they inflict upon bacterial membrane structures and minimal drug-resistance. Hence, synergistic NIR-II PTT and CDT hold great promise for enhancing the therapeutic efficacy of BBIs. Herein, we propose a biofilm microenvironment (BME)-responsive nanoplatform, BTFB@Fe@Van, for use in the synergistic NIR-II PTT/CDT/antibiotic treatment of BBIs. BTFB@Fe@Van was prepared through the self-assembly of phenylboronic acid (PBA)-modified small-molecule BTFB, vancomycin, and the CDT catalyst Fe2+ ions in DSPE-PEG2000. Vancomycin was conjugated with BTFB through a pH-sensitive PBA-diol interaction, while the Fe2+ ions were bonded to the sulfur and nitrogen atoms of BTFB. The PBA-diol bonds decomposed in the acidic BME, simultaneously freeing the vancomycin and Fe2+ irons. Subsequently, the catalytic product hydroxyl radical was generated by the Fe2+ ions in the oxidative BME overexpressed with H2O2. Moreover, under 1064 nm laser, BTFB@Fe@Van exhibited outstanding hyperthermia and accelerated the release rate of vancomycin and the efficacy of CDT. Furthermore, the BTFB@Fe@Van nanoplatform enabled the precise NIR-II imaging of the infected sites. Both in-vitro and in-vivo experiments demonstrated that BTFB@Fe@Van possesses a synergistic NIR-II PTT/CDT/antibiotic mechanism against BBIs.

Recent Advances of Composite Nanomaterials for Antibiofilm Application

A biofilm is a microbial community formed by bacteria that adsorb on the surface of tissues or materials and is wrapped in extracellular polymeric substances (EPS) such as polysaccharides, proteins and nucleic acids. As a protective barrier, the EPS can not only prevent the penetration of antibiotics and other antibacterial agents into the biofilm, but also protect the bacteria in the biofilm from the attacks of the human immune system, making it difficult to eradicate biofilm-related infections and posing a serious threat to public health. Therefore, there is an urgent need to develop new and efficient antibiofilm drugs. Although natural enzymes (lysozyme, peroxidase, etc.) and antimicrobial peptides have excellent bactericidal activity, their low stability in the physiological environment and poor permeability in biofilms limit their application in antibiofilms. With the development of materials science, more and more nanomaterials are being designed to be utilized for antimicrobial and antibiofilm applications. Nanomaterials have great application prospects in antibiofilm because of their good biocompati-bility, unique physical and chemical properties, adjustable nanostructure, high permeability and non-proneness to induce bacterial resistance. In this review, with the application of composite nanomaterials in antibiofilms as the theme, we summarize the research progress of three types of composite nanomaterials, including organic composite materials, inorganic materials and organic-inorganic hybrid materials, used as antibiofilms with non-phototherapy and phototherapy modes of action. At the same time, the challenges and development directions of these composite nanomaterials in antibiofilm therapy are also discussed. It is expected we will provide new ideas for the design of safe and efficient antibiofilm materials.