Metal-Organic Frameworks Meet Polymers: From Synthesis Strategies to Healthcare Applications

DNA-functionalized MOF fluorescent probes for the enzyme-free and pretreatment-free detection of MicroRNA in serum

MicroRNA (miRNA) is a promising biomarker that plays an important role in various biomedical applications, especially in cancer diagnosis. However, the current miRNA detection technology has inherent limitations such as complex operation, expensive testing cost and excessive detection time. In this study, a dual signal amplification biosensor based on DNA-functionalized metal-organic frameworks (MOFs) fluorescent probes, MFPBiosensor, was established for the enzyme-free and pretreatment-free detection of the colon cancer (CC) marker miR-23a. DNA-functionalized MOFs NH2-MIL-53(Al) (DNA@MOFs) were synthesized as fluorescent probes with specific recognition functions. A single DNA@MOF carries a large number of fluorescent ligands 2-aminoterephthalic acid (NH2-H2BDC), which can generate strong fluorescence signals after alkaline hydrolysis. Combined with catalyzed hairpin assembly (CHA), an efficient isothermal amplification technique, the dual signal enhancement strategy reduced matrix interference and sensitized the signal response. The established MFPBiosensor successfully detected extremely low levels of miRNA in complex biological samples with acceptable sensitivity and specificity. With a single detection cost of $0.583 and a test time of 50 min, the excellent inexpensive and rapid advantage of the MFPBiosensor is highlighted. More importantly, the subtle design enables the MFPBiosensor to achieve convenient batch detection, where miRNA in serum can be directly detected without any pretreatment process or enzyme. In conclusion, MFPBiosensor is a promising biosensor with substantial potential for commercial miRNA detection and clinical diagnostic applications of CC.

By Introducing Multiple Hydrogen Bonds Endows MOF Electrodes with an Enhanced Structural Stability

Recently, metal-organic frameworks (MOFs) have attracted great interest in energy storage areas. However, the poor structural stability of MOFs derived from weak coordination bonds limits their applications. Here, quadruple hydrogen bonds (H-bonds) were introduced onto the MOFs to enhance their structural stability. Cross-linked networks could be formed between molecules owing to multiple H-bonds, strengthening the framework stability. Moreover, the dynamic reversibility of H-bonds could endow MOFs with self-healing ability. Furthermore, due to lower binding energy compared to coordination bonds, H-bonds break preferentially when subjected to internal stress, thus protecting the MOFs. Consequently, the as-prepared self-healing hybrid (SHH-Cu-MOF@Ti3C2TX) exhibited high capacitance retention (89.4%) after 5000 cycles at 1 A g-1, while that hybrid without dynamic H-bonds (H-Cu-MOF@Ti3C2TX) presented a 79.9% retention, delivering an enhancement in cycling stability. Moreover, an asymmetric supercapacitor (ASC) was fabricated by employing SHH-Cu-MOF@Ti3C2TX and activated carbon (AC) as the electrodes. The ASC delivered a specific capacitance (47.4 F g-1 at 1 A g-1), an energy density (16.9 Wh kg-1), and a power density (800 W kg-1) as well as good rate ability (retains 81% of its initial capacitance from 0.2 A g-1 to 5 A g-1).

Ultrathin photonic crystal based on photo-crosslinked polymer and metal-organic framework for highly sensitive detection and discrimination of benzene series vapors

Volatile organic compounds (VOCs) have always been a major concern as a global environmental problem. As a low-cost, high-efficiency and visual sensor, photonic crystals (PCs) have been actively studied in VOCs detection. Herein, a one-dimensional PC sensor for visual sensing of highly toxic benzene series VOC vapors is prepared for the first time by integrating a new photo-crosslinked polymer-poly(styrene-benzoylphenyl acrylate) P(St-BPA) and a high specific surface area metal-organic framework (MOF) MIL-101(Cr). The PC can detect VOCs quantitatively and visually, and clearly distinguish 7 benzene series vapors. The detection limit of the benzene series VOCs is as low as 0.06-3.45 g/m3. Meanwhile, owing to the ultra-thin layer and porous structure, the PC can reach a response equilibrium to the VOCs within 1-2.6 s. Moreover, the PC has a good organic vapor tolerance and can maintain stable optical performance after 1000 times of reuse in VOCs. Besides, 4 other PCs assembled with different aryl polymers and MOFs are first fabricated and their sensing performance to benzene series VOCs are studied and compared, which provides a valuable reference for the selection of materials for the preparation of such PC sensors.

Metal-Organic Framework-Based Nanomaterials for Regulation of the Osteogenic Microenvironment

As the global population ages, bone diseases have become increasingly prevalent in clinical settings. These conditions often involve detrimental factors such as infection, inflammation, and oxidative stress that disrupt bone homeostasis. Addressing these disorders requires exogenous strategies to regulate the osteogenic microenvironment (OME). The exogenous regulation of OME can be divided into four processes: induction, modulation, protection, and support, each serving a specific purpose. To this end, metal-organic frameworks (MOFs) are an emerging focus in nanomedicine, which show tremendous potential due to their superior delivery capability. MOFs play numerous roles in OME regulation such as metal ion donors, drug carriers, nanozymes, and photosensitizers, which have been extensively explored in recent studies. This review presents a comprehensive introduction to the exogenous regulation of OME by MOF-based nanomaterials. By discussing various functional MOF composites, this work aims to inspire and guide the creation of sophisticated and efficient nanomaterials for bone disease management.

Enhancing anti-angiogenic immunotherapy for melanoma through injectable metal-organic framework hydrogel co-delivery of combretastatin A4 and poly(I:C)

The interplay between vascularization and macrophage-induced immune suppression plays a crucial role in melanoma treatment. In this study, we propose a novel combination approach to combat melanoma by simultaneously inhibiting tumor vascularization and enhancing macrophage-mediated anti-tumor responses. We investigate the potential of combining combretastatin A4 (CA4), a vascular-disrupting agent, with poly(I:C) (PIC), an immunostimulatory adjuvant. This combination approach effectively suppresses melanoma cell proliferation, disrupts vascularization, and promotes macrophage polarization towards the M1 phenotype for melanoma suppression. To facilitate efficient co-delivery of CA4 and PIC for enhanced anti-angiogenic immunotherapy, we develop an injectable metal-organic framework hydrogel using Zeolitic Imidazolate Framework-8 (ZIF-8) and hyaluronic acid (HA) (ZIF-8/HA). Our findings demonstrate that ZIF-8 enables efficient loading of CA4 and enhances the stability of PIC against RNAase degradation in vitro. Furthermore, the developed co-delivery hydrogel system, PIC/CA4@ZIF-8/HA, exhibits improved rheological properties, good injectability and prolonged drug retention. Importantly, in vivo experiments demonstrate that the PIC/CA4@ZIF-8/HA formulation significantly reduces the dosage and administration frequency while achieving a more pronounced therapeutic effect. It effectively inhibits melanoma growth by suppressing angiogenesis, destroying blood vessels, promoting M1 macrophage infiltration, and demonstrating excellent biocompatibility. In conclusion, our study advances anti-angiogenic immunotherapy for melanoma through the potent combination of PIC/CA4, particularly when administered using the PIC/CA4@ZIF-8/HA formulation. These findings provide a new perspective on clinical anti-angiogenic immunotherapy for melanoma, emphasizing the importance of targeting tumor vascularization and macrophage-mediated immune suppression simultaneously.

Metal-Organic Framework-Based Antimicrobial Touch Surfaces to Prevent Cross-Contamination

Infection diseases are a major threat to global public health, with nosocomial infections being of particular concern. In this context, antimicrobial coatings emerge as a promising prophylactic strategy to reduce the transmission of pathogens and control infections. Here, antimicrobial door handle covers to prevent cross-contamination are prepared by incorporating iodine-loaded UiO-66 microparticles into a potentially biodegradable polyurethane polymer (Baycusan eco E 1000). These covers incorporate MOF particles that serve as both storage reservoirs and delivery systems for the biocidal iodine. Under realistic touching conditions, the door handle covers completely inhibit the transmission of Gram-positive bacterial species (Staphylococcus aureus, and Enterococcus faecalis), Gram-negative bacterial species (Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii), and fungi (Candida albicans). The covers remain effective even after undergoing multiple contamination cycles, after being cleaned, and when tinted to improve discretion and usability. Furthermore, as the release of iodine from the door handle covers follow hindered Fickian diffusion, their antimicrobial lifetime is calculated to be as long as approximately two years. Together, these results demonstrate the potential of these antimicrobial door handle covers to prevent cross-contamination, and underline the efficacy of integrating MOFs into innovative technologies.

Molecular-caged metal-organic frameworks for energy management

Metal-organic frameworks (MOFs) hold great promise for diverse applications when combined with polymers. However, a persistent challenge lies in the susceptibility of exposed MOF pores to molecule and polymer penetration, compromising the porosity and overall performance. Here, we design a molecular-caged MOF (MC-MOF) to achieve contracted window without sacrificing the MOF porosity by torsional conjugated ligands. These molecular cages effectively shield against the undesired molecule penetration during polymerization, thereby preserving the pristine porosity of MC-MOF and providing outstanding light and thermal management to the composites. The polymer containing 0.5 wt % MC-MOF achieves an 83% transmittance and an exceptional haze of 93% at 550 nanometers, coupled with remarkable thermal insulation. These MC-MOF/polymer composites offer the potential for more uniform daylighting and reduced energy consumption in sustainable buildings when compared to traditional glass materials. This work delivers a general method to uphold MOF porosity in polymers through molecular cage design, advancing MOF-polymer applications in energy and sustainability.

Integrating Full-Color 2D Optical Waveguide and Heterojunction Engineering in Halide Microsheets for Multichannel Photonic Logical Gates

Ensuring information security has emerged as a paramount concern in contemporary human society. Substantial advancements in this regard can be achieved by leveraging photonic signals as the primary information carriers, utilizing photonic logical gates capable of wavelength tunability across various time and spatial domains. However, the challenge remains in the rational design of materials possessing space-time-color multiple-resolution capabilities. In this work, a facile approach is proposed for crafting metal-organic halides (MOHs) that offer space-time-color resolution. These MOHs integrate time-resolved room temperature phosphorescence and color-resolved excitation wavelength dependencies with both space-resolved ex situ optical waveguides and in situ heterojunctions. Capitalizing on these multifaceted properties, MOHs-based two-dimensional (2D) optical waveguides and heterojunctions exhibit the ability to tune full-color emissions across the spectra from blue to red, operating within different spatial and temporal scales. Therefore, this work introduces an effective methodology for engineering space-time-color resolved MOH microstructures, holding significant promise for the development of high-density photonic logical devices.

A Zn-modified PCN-224 fluorescent nanoprobe for selective and sensitive turn-on detection of glutathione

Monitoring endogenous glutathione (GSH) levels in living cells is essential for cancer diagnose and treatment. In this work, GSH responsive fluorescent nanoprobe with turn-on property was constructed using Zn-modified porphyrinic metal-organic frameworks (PCN-224-Zn). The introduced Zn2+ could quench the fluorescence of PCN-224 by the metallization of organic ligand (TCPP) and serves as sensing site for GSH. When exposed to GSH, the strong binding affinity of GSH generates the formation of Zn-GSH complex, eliminating the fluorescence quenching effect of Zn2+. Based on the constructed PCN-224-Zn nanoprobe, selective determination of GSH was achieved in the range of 0.01-6 μM with a detection limit of 1.5 nM. Furthermore, the constructed nanoprobe can realize the fluorescence imaging of endogenous GSH in MCF-7 and HeLa cells. Meanwhile, PCN-224-Zn could also monitor GSH in cell lysate with recovery rates from 93.8 % to 102.3 %. The performance of PCN-224-Zn demonstrates its capacities in the application of fluorescence sensing and bio-imaging fields.

From biomaterials to biotherapy: cuttlefish ink with protoporphyrin IX nanoconjugates for synergistic sonodynamic-photothermal therapy

Biologically produced nanomaterials capable of therapeutic purposes have received increasing interest in tumor therapy because of their intrinsic biocompatibility. In this study, we made cuttlefish ink (extracted from cuttlefish) and protoporphyrin IX (PpIX) nanoconjugates (CIPs) where PpIX was an endogenous organic compound. In the case of CIPs, PpIX could be triggered by ultrasound (US) for sonodynamic therapy (SDT), and the cuttlefish ink could be excited by a near-infrared laser for photothermal therapy (PTT). Thereafter, tumor growth was greatly inhibited through synergistic SDT-PTT in comparison to single SDT or PTT. In addition, in vivo administration of CIPs showed no noticeable side effects for mouse blood and chief organs, providing an effective strategy for developing biologically produced biomaterials and using them for biotherapy.

Dual Stimulus-Responsive Enzyme@Metal-Organic Framework-Polymer Composites toward Enhanced Catalytic Performance for Visual Detection of Glucose

Enzyme immobilization on a metal-organic framework (enzyme@MOF) has been proven to be a promising strategy for boosting catalysis and biosensing applications. However, promoting the catalytic performance of polymer-modified enzyme@MOF composites remains an ongoing challenge. Herein, a protocol for enzyme immobilization was designed by using a smart polymer-modified MOF (UiO-66-NH2, UN) as the support. Through in situ polymerization, the dual stimulus-responsive poly(N-2-dimethylamino ethyl methacrylate) (PDM) was prepared. The PDM as a "soft cage" protected the immobilized glucose oxidase (GOx)-horseradish peroxidase (HRP) on the surface of the rigid UN. The confinement effect was generated by varying the temperature and pH, thereby improving the catalytic activity of the GOx-HRP@UN-PDM composites. In comparison with free enzymes, the fabricated composites exhibited an 8.9-fold enhancement in catalytic performance (Vmax) at pH 5.0 and 49 °C. Furthermore, relying on a cascade reaction generated in the composites, an assay was developed for the visual detection of glucose in rat serum. This study introduces a groundbreaking approach for the construction of smart enzyme@MOF-polymer composites with high catalytic activity for sensitive monitoring of biomolecules.

Rational Design of Guanidinium-Based Bio-MCOF as a Multifunctional Nanocatalyst in Tumor Cells for Enhanced Chemodynamic Therapy

Chemodynamic therapy (CDT) has emerged as a promising approach to cancer treatment, which can break the intracellular redox state balance and result in severe oxidative damage to biomolecules and organelles with the advantages of being less dependent on external stimulation, having deep tissue-healing abilities, and being resistant to drug resistance. There is considerable interest in developing CDT drugs with high efficiency and low toxicity. In this study, a new guanidinium-based biological metal covalent organic framework (Bio-MCOF), GZHMU-1@Mo, is rationally designed and synthesized as a multifunctional nanocatalyst in tumor cells for enhanced CDT. The DFT calculation and experimental results showed that due to the ability of MoO42- ion to promote electron transfer and increase the redox active site, Cu3 clusters and MoO42- ions in GZHMU-1@Mo can synergistically catalyze the production of reactive oxygen species (ROS) from oxygen and H2O2 in tumor cells, as well as degrade intracellular reducing substances, GSH and NADH, so as to disrupt the redox balance in tumor cells. Moreover, GZHMU-1@Mo exhibits a potent killing effect on tumor cells under both normal oxygen and anaerobic conditions. Further in vitro and in vivo antiproliferation studies revealed that the GZHMU-1@Mo nanoagent displays a remarkable antiproliferation effect and effectively inhibits tumor growth. Taken together, our study provides an insightful reference benchmark for the rational design of Bio-MCOF-based nanoagents with efficient CDT.

Magnetic Metal-Organic Framework-Based Nanoplatform with Platelet Membrane Coating as a Synergistic Programmed Cell Death Protein 1 Inhibitor against Hepatocellular Carcinoma

Programmed cell death protein 1 (PD-1) inhibitors are the most common immune-checkpoint inhibitors and considered promising drugs for hepatocellular carcinoma (HCC). However, in clinical settings, they have a low objective response rate (15%-20%) for patients with HCC; this is because of the insufficient level and activity of tumor-infiltrating T lymphocytes (TILs). The combined administration of oxymatrine (Om) and astragaloside IV (As) can increase the levels of TILs by inhibiting the activation of cancer-associated fibroblasts (CAFs) and improve the activity of TILs by enhancing their mitochondrial function. In the present study, we constructed a magnetic metal-organic framework (MOF)-based nanoplatform with platelet membrane (Pm) coating (PmMN@Om&As) to simultaneously deliver Om and As into the HCC microenvironment. We observed that PmMN@Om&As exhibited a high total drug-loading capacity (33.77 wt %) and good immune escape. Furthermore, it can target HCC tissues in a magnetic field and exert long-lasting effects. The HCC microenvironment accelerated the disintegration of PmMN@Om&As and the release of Om&As, thereby increasing the level and activity of TILs by regulating CAFs and the mitochondrial function of TILs. In addition, the carrier could synergize with Om&As by enhancing the oxygen consumption rate and proton efflux rate of TILs, thereby upregulating the mitochondrial function of TILs. Combination therapy with PmMN@Om&As and α-PD-1 resulted in a tumor suppression rate of 84.15% and prolonged the survival time of mice. Our study provides a promising approach to improving the antitumor effect of immunotherapy in HCC.

Positional Isomers of Covalent Organic Frameworks for Indoor Humidity Regulation

Humidity is one of the most important indicators affecting human health. Here, a pair of covalent organic frameworks (COFs) of positional isomers (p-COF and o-COF) for indoor humidity regulation is reported. Although p-COF and o-COF have the same sql topology and pore size, they exhibit different water adsorption behaviors due to the subtle differences in water adsorption sites. Particularly, o-COF exhibits a steep adsorption isotherm in the range of 45-65% RH with a hysteresis loop, which is perfectly suitable for indoor humidity regulation. In the laboratory experiment, when the humidity of the external environment is 20-75% RH, o-COF can control the humidity of the room in the range of 45-60% RH. o-COF has shown great potential as a dual humidification/dehumidification adsorbent for indoor humidity regulation.

Recent Advances in Multifunctional Reticular Framework Nanoparticles: A Paradigm Shift in Materials Science Road to a Structured Future

Porous organic frameworks (POFs) have become a highly sought-after research domain that offers a promising avenue for developing cutting-edge nanostructured materials, both in their pristine state and when subjected to various chemical and structural modifications. Metal-organic frameworks, covalent organic frameworks, and hydrogen-bonded organic frameworks are examples of these emerging materials that have gained significant attention due to their unique properties, such as high crystallinity, intrinsic porosity, unique structural regularity, diverse functionality, design flexibility, and outstanding stability. This review provides an overview of the state-of-the-art research on base-stable POFs, emphasizing the distinct pros and cons of reticular framework nanoparticles compared to other types of nanocluster materials. Thereafter, the review highlights the unique opportunity to produce multifunctional tailoring nanoparticles to meet specific application requirements. It is recommended that this potential for creating customized nanoparticles should be the driving force behind future synthesis efforts to tap the full potential of this multifaceted material category.