Antibacterial application and toxicity of metal-organic frameworks

Research progress on antibacterial applications of metal-organic frameworks and their biomacromolecule composites

With the extensive use of antibiotics, resulting in increasingly serious problems of bacterial resistance, antimicrobial therapy has become a global concern. Metal-organic frameworks (MOFs) are low-density porous coordination materials composed of metal ions and organic ligands, which can form composite materials with biomacromolecules such as proteins and polysaccharides. In recent years, MOFs and their derivatives have been widely used in the antibacterial field as efficient antibacterial agents. This review offers a detailed summary of the antibacterial applications of MOFs and their composites, and the different synthesis methods and antibacterial mechanisms of MOFs and MOF-based composites are briefly introduced. Finally, the challenges and prospects of MOFs-based antibacterial materials in the rapidly developing medical field were briefly discussed. We hope this review will provide new strategies for the medical application of MOFs-based antibacterial materials.

Metal-organic framework-based advanced therapeutic tools for antimicrobial applications

The escalating concern over conventional antibiotic resistance has emphasized the urgency in developing innovative antimicrobial agents. In recent times, metal-organic frameworks (MOFs) have garnered significant attention within the realm of antimicrobial research due to their multifaceted antimicrobial attributes, including the sustained release of intrinsic or exogenous antimicrobial components, chemodynamically catalyzed generation of reactive oxygen species (ROS), and formation of photogenerated ROS. This comprehensive review provides a thorough overview of the synthetic approaches employed in the production of MOF-based materials, elucidating their underlying antimicrobial mechanisms in depth. The focal point lies in elucidating the research advancements across various antimicrobial modalities, encompassing intrinsic component release system, extraneous component release system, auto-catalytical system, and energy conversion system. Additionally, the progress of MOF-based antimicrobial materials in addressing wound infections, osteomyelitis, and periodontitis is meticulously elucidated, culminating in a summary of the challenges and potential opportunities inherent within the realm of antimicrobial applications for MOF-based materials. STATEMENT OF SIGNIFICANCE: Growing concerns about conventional antibiotic resistance emphasized the need for alternative antimicrobial solutions. Metal-organic frameworks (MOFs) have gained significant attention in antimicrobial research due to their diverse attributes like sustained antimicrobial components release, catalytic generation of reactive oxygen species (ROS), and photogenerated ROS. This review covers MOF synthesis and their antimicrobial mechanisms. It explores advancements in intrinsic and extraneous component release, auto-catalysis, and energy conversion systems. The paper also discusses MOF-based materials' progress in addressing wound infections, osteomyelitis, and periodontitis, along with existing challenges and opportunities. Given the lack of related reviews, our findings hold promise for future MOF applications in antibacterial research, making it relevant to your journal's readership.

CD-MOFs: From preparation to drug delivery and therapeutic application

Cyclodextrin metal-organic frameworks (CD-MOFs) show considerable advantages of edibility, degradability, low toxicity, and high drug loading, which have attracted enormous interest, especially in drug delivery. This review summarizes the typical synthesis approaches of CD-MOFs, the drug loading methods, and the mechanism of encapsulation and release. The influence of the structure of CD-MOFs on their drug encapsulation and release is highlighted. Finally, the challenges CD-MOFs face are discussed regarding biosafety assessment systems, stability in aqueous solution, and metal ion effect.

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

Bacterial infections pose a significant threat to global public health; therefore, the development of novel therapeutics is urgently needed. Herein, a controllable antibacterial nanoplatform utilizing cyclodextrin metal-organic frameworks (CD-MOFs) as a template to synthesize ultrafine silver nanoparticles (Ag NPs) in their porous structure is constructed. Subsequently, polydopamine (PDA) is encapsulated on the CD-MOFs' surface via dopamine polymerization to enhance the water stability and enable hyperthermia capacity. The resulting Ag@MOF@PDA generates localized hyperthermia and gradually releases Ag+ to achieve long-term photothermal-chemical bactericidal capability. The release rate of Ag+ can be accelerated by NIR-mediated heating in a controllable manner, quickly reaching the effective concentration and reducing the frequency of medication to avoid potential toxicity. In vitro experiments demonstrate that the combined antibacterial strategy can not only effectively kill both gram-negative and gram-positive bacteria, but also directly eradicate mature biofilms. In vivo results confirm that both bacterial- and biofilm-infected wounds treated with a combination of Ag@MOF@PDA and laser exhibit satisfactory recovery with minimal toxicity, displaying a superior therapeutic effect compared to other groups. Together, the results warrant that the Ag@MOF@PDA realizes synergistic antibacterial capacity and controllable release of Ag+ to combat bacterial and biofilm infections, providing a potential antibiotic-free alternative in the "post-antibiotic era."

Collaboration of two-star nanomaterials: The applications of nanocellulose-based metal organic frameworks composites

Nanocellulose, as the star nanomaterial in carbohydrate polymers, has excellent mechanical properties, biodegradability, and easy chemical modification. However, further practical applications of nanocellulose are limited by their inadequate functionalization. Metal-organic frameworks (MOFs), as the star nanomaterial in functional polymers, have a large surface area, high porosity, and adjustable structure. The collaboration of nanocellulose and MOFs is a desirable strategy to make composites especially interesting for multifunctional and multi-field applications. What sparks will be produced by the collaboration of two-star nanomaterials? In this review article, we highlight an up-to-date overview of nanocellulose-based MOFs composites. The sewage treatment, gas separation, energy storage, and biomedical applications are mainly summarized. Finally, the challenges and research trends of nanocellulose-based MOFs composites are prospected. We hope this review may provide a valuable reference for the development and applications of carbohydrate polymer composites soon.

Predicting the bioavailability of nitro polycyclic aromatic hydrocarbons in sediments: ZIF-8/h-BN solid-phase microextraction versus Tenax extraction

The occurrence of nitrated polycyclic aromatic hydrocarbons (NPAHs) in sediments has been widely reported, but research on NPAH bioavailability is lacking. In this study, a self-made zeolite imidazolate framework-8/hexagonal boron nitride (ZIF-8/h-BN) solid-phase microextraction (SPME) fiber and commercial Tenax are compared as efficient tools to predict the bioavailability of NPAHs in sediments with bioassays using Cipangopaludina chinensis. During the process of SPME, the NPAH concentrations on the ZIF-8/h-BN fibers reached extraction equilibrium after 72 h. The fiber extraction of NPAHs in sediments was well-fitted by the pseudo first-order kinetic model with a rate constant of 2 × 10^-2 h^-1 (R² > 0.98). The extraction rates ranking of NPAHs in sediments was 2-nitrobiphenyl>1-nitropyrene>5-nitroacenaphthene>2-nitrofluorene. Compared with SPME, NPAH concentrations reached equilibrium after 168 h for the Tenax extraction. The orders of magnitude of fast, slow, and very slow desorption rate constants were 10^-1, 10^-2, and 10^-4, respectively. At extraction equilibrium (168 h), the SPME was close to the bioavailability of the NPAHs in sediments to Cipangopaludina chinensis with a slope statistically approximated to one. In addition, the linear regression for SPME (R² = 0.7285) was slightly higher than that of the Tenax extraction (R² = 0.7168) over a short time (6 h). This could be because the coating material of ZIF-8/h-BN can rapidly adsorb freely dissolved NPAHs, and the SPME fibers can accurately predict the bioaccumulated concentrations of NPAHs in exposed organisms by measuring the concentration of NPAHs in the pore water of sediment. This study provides a time-saving and easy procedure to predict the bioavailability of NPAHs in sediments.

Metal-organic frameworks: A promising option for the diagnosis and treatment of Alzheimer's disease

Beta-amyloid (Aβ) peptide is one of the main characteristic biomarkers of Alzheimer's disease (AD). Previous clinical investigations have proposed that unusual concentrations of this biomarker in cerebrospinal fluid, blood, and brain tissue are closely associated with the AD progression. Therefore, the critical point of early diagnosis, prevention, and treatment of AD is to monitor the levels of Aβ. In view of the potential of metal-organic frameworks (MOFs) for diagnosing and treating the AD, much attention has been focused in recent years. This review discusses the latest advances in the applications of MOFs for the early diagnosis of AD via fluorescence and electrochemiluminescence (ECL) detection of AD biomarkers, fluorescence detection of the main metal ions in the brain (Zn²⁺, Cu²⁺, Mn²⁺, Fe³⁺, and Al³⁺) in addition to magnetic resonance imaging (MRI) of the Aβ plaques. The current challenges and future strategies for translating the in vitro applications of MOFs into in vivo diagnosis of the AD are discussed.

ZIF-8 nanoparticles induce neurobehavioral disorders through the regulation of ROS-mediated oxidative stress in zebrafish embryos

Zeolite imidazolate framework-8 (ZIF-8) is a nanomaterial of metal-organic frameworks (MOFs), which have various applications in drug delivery and water pollution remediation. However, little is known about its developmental neurotoxicity in aquatic organisms, especially on the low-level exposure. In the present study, we investigated the toxic effects of ZIF-8 NPs on the neuron development, behavioral traits, oxidative stress and gene expression in zebrafish embryos. Firstly, our results showed that ZIF-8 induced significantly embryonic malformations and abnormal development of nervous system in zebrafish embryos with a concentration-dependent manner. Meanwhile, the locomotor behavior was obviously inhibited while the anxiety behavior was greatly increased after ZIF-8 exposure. Secondly, the levels of ROS and antioxidant enzyme activities (CAT, SOD and MDA) together with AChE and ATPase were substantially increased in the ZIF-8 exposed groups. At the molecular level, ZIF-8 NPs could down-regulate the expression profiles of neural development-related genes (gap43, synapsin 2a and neurogenin 1) and PD-like related genes (dj-1, dynactin and parkin), but up-regulate the expression levels of neuro-inflammatory genes (nox-1, glip1a and glip1b) in larval zebrafish. In addition, we further explored the molecular mechanism of neurotoxicity induced by ZIF-8 with pharmacological experiments. The results showed that specific inhibition of ROS-mediated oxidative stress by the astaxanthin could reverse the expression patterns of ATPase, AChE and neurodevelopmental genes. Moreover, astaxanthin can partially rescue the ZIF-8-modulated locomotor behavior. Taken together, our results demonstrated that ZIF-8 had the potential to cause neurotoxicity in zebrafish embryos. These informations presented in this study will help to elucidate the molecular mechanisms of ZIF-8 nanoparticles exposure in zebrafish, which providing a scientific evaluation of its safety to aquatic ecosystems.

Metal-organic frameworks for pharmaceutical and biomedical applications

Metal-organic framework (MOF) materials provide unprecedented opportunities for evaluating valuable compounds for various medical applications. MOFs merged with biomolecules, used as novel biomaterials, have become particularly useful in biological environments. Bio-MOFs can be promising materials in the global to avoid utilization above toxicological substances. Bio-MOFs with crystallin and porosity nature offer flexible structure via bio-linker and metal node variation, which improves their wide applicability in medical science.

Converging 2D Nanomaterials and 3D Bioprinting Technology: State-of-the-Art, Challenges, and Potential Outlook in Biomedical Applications

The development of next-generation of bioinks aims to fabricate anatomical size 3D scaffold with high printability and biocompatibility. Along with the progress in 3D bioprinting, 2D nanomaterials (2D NMs) prove to be emerging frontiers in the development of advanced materials owing to their extraordinary properties. Harnessing the properties of 2D NMs in 3D bioprinting technologies can revolutionize the development of bioinks by endowing new functionalities to the current bioinks. First the main contributions of 2D NMS in 3D bioprinting technologies are categorized here into six main classes: 1) reinforcement effect, 2) delivery of bioactive molecules, 3) improved electrical conductivity, 4) enhanced tissue formation, 5) photothermal effect, 6) and stronger antibacterial properties. Next, the recent advances in the use of each certain 2D NMs (1) graphene, 2) nanosilicate, 3) black phosphorus, 4) MXene, 5) transition metal dichalcogenides, 6) hexagonal boron nitride, and 7) metal-organic frameworks) in 3D bioprinting technology are critically summarized and evaluated thoroughly. Third, the role of physicochemical properties of 2D NMSs on their cytotoxicity is uncovered, with several representative examples of each studied 2D NMs. Finally, current challenges, opportunities, and outlook for the development of nanocomposite bioinks are discussed thoroughly.

Iodine Immobilized Metal-Organic Framework for NIR-Triggered Antibacterial Therapy on Orthopedic Implants

Iodine has been known as an effective disinfectant with broad-spectrum antimicrobial potency yet without drug resistance risk when used in clinic. However, the exploration of iodine for antibacterial therapy in orthopedics remains sparse due to its volatile nature and poor solubility. Herein, leveraging the superior absorption capability of metal-organic frameworks (MOFs) and their inherent photocatalytic properties, iodine-loaded MOF surface is presented to realize responsive iodine release along with intracellular reactive oxygen species(ROS) oxidation under near-infrared (NIR) exposure to achieve synergistic antibacterial effect. Iodine is successfully loaded using vapor deposition process onto zeolitic imidazolate framework-8(ZIF-8), which is immobilized onto micro arc oxidized titanium via a hydrothermal approach. The combination of NIR-triggered iodine release and ZIF-8 mediated ROS oxidative stress substantially augments the antibacterial efficacy of this approach both in vitro and in vivo. Furthermore, this composite coating also supported osteogenic differentiation of bone marrow stromal cells, as well as improved osseointegration of coated implants using an intramedullary rat model, suggesting improvement of antibacterial efficacy does not impair osteogenic potential of the implants. Altogether, immobilization of iodine via MOF on orthopedic implants with synergistic antibacterial effect can be a promising strategy to combat bacterial infections.