Metal-organic Framework Nanoparticles Research Articles

ChemFET Anion Sensor Based on MOF Nanoparticles.

Nanoparticles of metal-organic frameworks (nanoMOFs) possess the unusual combination of both internal and external surfaces. While internal surfaces have been the focus of fundamental and applications-based MOF studies, the chemistry of the external surfaces remains scarcely understood. Herein we report that specific ion interactions with nanoparticles of Cu(1,2,3-triazolate)2 (Cu(TA)2) resemble the Hofmeister behavior of proteins and the supramolecular chemistry of synthetic macromolecules. Inspired by these anion-selective interactions, we tested the performance of Cu(TA)2 nanoparticles as chemical field effect transistor (ChemFET) anion sensors. Rather than size-based selectivity, the detection limits of the devices exhibit a Hofmeister trend, with the greatest sensitivity towards anions perchlorate, iodide, and nitrate. These results highlight the importance of the pore-based supramolecular interactions, rather than localized donor-acceptor pairs, in designing MOF-based technologies.

Corrosion-oriented self-healing coating based on ZnMg MOF for efficient corrosion protection of aluminum alloy via in-situ LDH film formation

A corrosion-oriented self-healing coating system relying on metal–organic framework (MOF) based nanofiller is designed for aluminum alloy protection. The nanofiller is comprise of ZnMg MOF nanoparticle as a framework, salicylaldoxime corrosion inhibitors inside the MOF, and a polydopamine layer on the MOF surface. The Al3+ ions generated from the aluminum alloy substrate at the damaged coating area can etch the nanofiller, causing the collapse of the nanofiller and releasing the corrosion inhibitors to suppress the corrosion process in time. Subsequently, Zn2+ and Mg2+ ions from the nanofiller co-precipitate with Al3+ to form a dense AlZnMg layered double hydroxide (LDH) film, which provides further protection performance at the exposed alloy surface. Electrochemical impedance spectroscopy results demonstrate that the intact MOF@S/P coating exhibits a remarkable corrosion resistance property. For the damaged coating, the self-healing performance originated from the formation of LDH layer and the release of corrosion inhibitors gradually took effect, with the |Z|0.01Hz value increasing 2.27 times within 14 days. Moreover, under near-infrared irradiation, the photothermal effect of polydopamine will accelerate the release of corrosion inhibitor, the formation of LDH film, as well as the shape memory effect of coating defect for an efficient recovery of the corrosion resistance property. This novel coating system enables a corrosion-driven and location-specific repair with in-situ deposition of both an inhibitor film and an LDH film. As the first work to fully utilize and consume nanofillers on demand, this approach prevents inadequate use of healing agents, addressing a significant challenge in corrosion-driven self-healing coatings. The self-healing mechanism ensures target-oriented corrosion protection that makes the most efficient use of the healing substances.

Targeting long non-coding RNA H19 in Subchondral Bone Osteocytes Alleviates Cartilage Degradation in Osteoarthritis.

Emerging evidence suggests long non-coding RNA (lncRNA) H19 is associated with osteoarthritis (OA) pathology. However, how H19 contributes to OA has not been reported. This study aims to investigate the biological function of H19 in OA subchondral bone remodeling and OA progression. Clinical joint samples and OA animal models induced by medial meniscus destabilization (DMM) surgery were used to verify the causal relationship between osteocyte H19 and OA subchondral bone and cartilage changes. MLO-Y4 osteocyte cells subjected to fluid shear stress were used to verify the mechanism underlying H19-mediated mechano-response. Finally, the antisense oligonucleotide (ASO) against H19 was delivered to mice knee joints by magnetic metal-organic framework (MMOF) nanoparticles in order to develop a site-specific delivery method for targeting osteocyte H19 for OA treatment. Both clinical OA subchondral bone and wildtype mice with DMM-induced OA exhibit aberrant higher subchondral bone mass with more H19 expressing osteocytes. On the contrary, osteocyte-specific deletion of H19 mice is less vulnerable to DMM-induced OA phenotype. In MLO-Y4 cells, H19-mediated osteocyte mechano-response through PI3K/AKT/GSK3 signals activation by EZH2-induced H3K27me3 regulation on PP2A inhibition. Targeted inhibition of H19 (using ASO-loaded MMOF) substantially alleviates subchondral bone remodeling and OA phenotype. In summary, our results provide new evidence that the elevated H19 expression in osteocytes may contribute to aberrant subchondral bone remodeling and OA progression. H19 appears to be required for the osteocyte response to mechanical stimulation, and targeting H19 represents a new promising approach for OA treatment.

Optimization and Investigation of Hemoglobin‐Loaded ZIF‐90 Metal–Organic Framework Nanoparticles as Artificial Oxygen Carriers

AbstractBlood transfusions are vital, yet limited shelf‐life and storage conditions of red blood cells (RBCs) hinder their use in emergencies. Hemoglobin‐based oxygen carriers (HBOCs) aim to address these challenges, but previous versions faced clinical setbacks due to safety concerns related to hemoglobin (Hb) extravasation. ZIF‐90, a novel metal–organic framework variant where imidazole‐2‐carboxaldehyde (2‐ICA) is bridged to Zn2+ ions, is explored. Optimizing Zn2+:2‐ICA ratios and Hb concentrations, Hb‐loaded ZIF‐90 nanoparticles (NPs) are synthesized in one‐step and under mild synthesis conditions. These NPs achieve a 25.1% yield, 7.0 mg mL−1 Hb concentration, 70.3% encapsulation efficiency (EE), and 96.4% drug loading. They exhibit a left‐shifted oxygen dissociation curve with p50 of ≈8 mmHg, indicating enhanced oxygen release at lower partial oxygen pressures as compared to native RBCs. This feature makes Hb‐loaded ZIF‐90 NPs suitable for certain medical applications including ischemia‐reperfusion injury management. Furthermore, the impact of two prominent capping agents: polyvinylpyrrolidone and polyethylene glycol (PEG) is assessed. PEG improves 2‐ICA incorporation and stabilizes the ZIF‐90 crystalline phase, albeit with reduced yield, Hb content, and EE. The findings underscore the potential of Hb‐loaded ZIF‐90 NPs as next‐generation HBOCs, offering enhanced uniformity, high Hb content, and efficient oxygen binding and release properties for medical applications.

Photosensitizing metal–organic framework nanoparticles combined with tumor-sensitization strategies can enhance the phototherapeutic effect upon medullary thyroid carcinoma

Photodynamic therapy (PDT) utilizing metal-organic frameworks (MOFs) has developed as a new and efficacious treatment for malignant tumors located on the surface of the human body. In order to achieve more effective PDT treatment outcomes, the traditional method has been to increase the intensity of the laser irradiation, but this approach can easily lead to tissue burns. In this study, we developed a new type of nanoparticle, F68-PKI@PCN224, aims to achieve effective PDT upon medullary thyroid carcinoma (MTC) which is an uncommon form of thyroid cancer that originates in the parafollicular cells of the thyroid and the therapeutic outlook for patients with MTC remains unsatisfactory. F68-PKI@PCN224 combines the antitumor features of PDT with mammalian target of rapamycin (mTOR) inhibitor PKI-587 (PKI). The tumor sensitization, slow release, and pH response features of F68-PKI@PCN224 was demonstrated by a series of in vitro and in vivo experiments / assays. F68-PKI@PCN224 achieved the long-term activation and slow releasing of PKI and TCPP in MTC tumor tissues. During the process of generating PDT effects, F68-PKI@PCN224 enhanced the tumor's sensitivity to PDT, direct laser irradiation of MTC cells or subcutaneous tumor tissues. As a result, low-dose phototherapy achieves a higher anti-tumor effect upon F68-PKI@PCN224 compared with TCPP. This study reveals the synergistic effect between tumor sensitization by mTOR inhibitor and PDT and initially unveils the mechanism of action of these nanoparticles.

Boosting the Strength and Toughness of Polymer Blends via Ligand-Modulated MOFs.

Mechanically robust and tough polymeric materials are in high demand for applications ranging from flexible electronics to aerospace. However, achieving both high toughness and strength in polymers remains a significant challenge due to their inherently contradictory nature. Here, a universal strategy for enhancing the toughness and strength of polymer blends using ligand-modulated metal-organic framework (MOF) nanoparticles is presented, which are engineered to have adjustable hydrophilicity and lipophilicity by varying the types and ratios of ligands. Molecular dynamics (MD) simulations demonstrate that these nanoparticles can effectively regulate the interfaces between chemically distinct polymers based on their amphiphilicity. Remarkably, a mere 0.1wt.% of MOF nanoparticles with optimized amphiphilicity (ML-MOF(5:5)) delivered ≈3.4- and ≈34.1-fold increase in strength and toughness of poly (lactic acid) (PLA)/poly (butylene succinate) (PBS) blend, respectively. Moreover, these amphiphilicity-tailorable MOF nanoparticles universally enhance the mechanical properties of various polymer blends, such as polypropylene (PP)/polyethylene (PE), PP/polystyrene (PS), PLA/poly (butylene adipate-co-terephthalate) (PBAT), and PLA/polycaprolactone (PCL)/PBS. This simple universal method offers significant potential for strengthening and toughening various polymer blends.

Assessment of the Potential Effect of S-Methylcysteine Alone and in Combination with Metal-Organic Framework Nanoparticles on Experimental Toxoplasmosis in Immunosuppressed Mice

Assessment of the Potential Effect of S-Methylcysteine Alone and in Combination with Metal-Organic Framework Nanoparticles on Experimental Toxoplasmosis in Immunosuppressed Mice

Co-Delivery of VEGF siRNA and THPP via Metal-Organic Framework Reverses Cisplatin-Resistant Non-Small Cell Lung Cancer and Inhibits Metastasis through a MUC4 Regulating Mechanism.

Cisplatin resistance significantly impacts the antitumor efficacy of cisplatin chemotherapy and contributes to poor prognosis, including metastasis. In this study, we present the utilization of metal-organic framework (MOF) nanoparticles as the therapeutic component and drug loading scaffold for implementing a ternary combination therapeutic strategy to combat cisplatin-resistant lung cancer and metastasis. Specifically, by engineering MOFs (Cis@MOF-siVEGF) through the self-assembly of THPP as photosensitizer for photodynamic therapy (PDT), along with the incorporation of cisplatin (DDP) and VEGF siRNA (siVEGF), we propose the leverage of photodynamic-induced oxidative damage and gene silencing of the angiogenic factor to reverse cisplatin resistance and sensitize therapeutic potency. Our findings demonstrated that the chemo/photodynamic/antiangiogenic triple combination therapy via Cis@MOF-siVEGF under irradiation effectively inhibits cisplatin-resistant tumor growth and induces abscopal effects. Importantly, molecular mechanistic exploration suggested that MUC4 exerted regulatory effects on governing cancer metastasis, thus representing a potential immunotherapeutic target for cancer intervention. Overall, our study creates a MOFs-based multicomponent delivery platform for complementary therapeutic modules with synergistically enhanced antitumor efficacy and sheds light on potential regulatory mechanisms on cisplatin-resistance cancers.

Blood-Brain Barrier-Penetrating Metal-Organic Framework Antioxidant Nanozymes for Targeted Ischemic Stroke Therapy.

Overproduction of reactive oxygen species (ROS) during reperfusion in ischemic stroke (IS) severely impedes neuronal survival and results in high rates of morbidity and disability. The effective blood-brain barrier (BBB) penetration and brain delivery of antioxidative agents remain the biggest challenge in treating ischemic reperfusion-induced cerebrovascular and neural injury. In this study, a metal-organic framework (MOF) nanozyme (MIL-101-NH2(Fe/Cu)) with ROS scavenging activities to encapsulate neuroprotective agent rapamycin is fabricated and decorating the exterior with BBB-targeting protein ligands (transferrin), thereby realizing enhanced drug retention and controlled release within ischemic lesions for the synergistic treatment of IS. Through the receptor-mediated transcellular pathway, the transferrin-coated MOF nanoparticles achieved efficient transport across the BBB and targeted accumulation at the cerebral ischemic injury site of mice with middle cerebral artery occlusion/reperfusion (MCAO/R), wherein the nanocarrier exhibited catalytic activities of ROS decomposition into O2 and H2O2-responsive rapamycin release. By its BBB-targeting, antioxidative, anti-inflammatory, and antiapoptotic properties, the MOF nanosystem addressed multiple pathological factors of IS and realized remarkable neuroprotective effects, leading to the substantial reduction of cerebral infarction volume and accelerated recovery of nerve functions in the MCAO/R mouse model. This MOF-based nanomedicine provides valuable design principles for effective IS therapy with multi-mechanism synergies.

Bifunctional mesoporous HMUiO-66-NH2 nanoparticles for bone remodeling and ROS scavenging in periodontitis therapy

Periodontal bone defects represent an irreversible consequence of periodontitis associated with reactive oxygen species (ROS). However, indiscriminate removal of ROS proves to be counterproductive for tissue repair and insufficient for addressing existing bone defects. In the treatment of periodontitis, it is crucial to rationally alleviate local ROS while simultaneously promoting bone regeneration. In this study, Zr-based large-pore hierarchical mesoporous metal-organic framework (MOF) nanoparticles (NPs) HMUiO-66-NH2 were successfully proposed as bifunctional nanomaterials for bone regeneration and ROS scavenging in periodontitis therapy. HMUiO-66-NH2 NPs demonstrated outstanding biocompatibility both in vitro and in vivo. Significantly, these NPs enhanced the osteogenic differentiation of bone mesenchymal stem cells (BMSCs) under normal and high ROS conditions, upregulating osteogenic gene expression and mitigating oxidative stress. Furthermore, in vivo imaging revealed a gradual degradation of HMUiO-66-NH2 NPs in periodontal tissues. Local injection of HMUiO-66-NH2 effectively reduced bone defects and ROS levels in periodontitis-induced C57BL/6 mice. RNA sequencing highlighted that differentially expressed genes (DEGs) are predominantly involved in bone tissue development, with notable upregulation in Wnt and TGF-β signaling pathways. In conclusion, HMUiO-66-NH2 exhibits dual functionality in alleviating oxidative stress and promoting bone repair, positioning it as an effective strategy against bone resorption in oxidative stress-related periodontitis.

In situ growth of ZIF-8 on cellulose microspheres with high doxorubicin loading capacity and pH-sensitive for oral drug delivery

Metal-organic framework (MOF) nanoparticles are a class of porous nanomaterials with wide application prospects. Zeolitic imidazolate framework (ZIF) materials have high loading performance and pH-sensitive characteristics, which means they have great development prospects in the development of drug carrier systems. Herein, cellulose microspheres (CM) were used as a carrier for the nucleation and growth of ZIF-8 nanocrystals. CM@ZIF-8 was prepared in situ, which was more convenient, flexible, cost-effective, and highly safe. CM@ZIF-8, as a novel carrier, was used to monitor the release of the anticancer drug Doxorubicin (DOX) and prevent it from dissipating before reaching its goal. The designed DOX-loaded CM@ZIF-8 (CM@ZIF-8-DOX) system was characterized by FTIR, SEM, N2 sorption isotherm, XRD, and Cytotoxicity assay (cells survival rate 95.08 %). CM@ZIF-8-DOX exhibited controlled drug release behavior in simulated in-vitro tumor microenvironments (81.2 % drug release throughout 72h). CM@ZIF-8 simultaneously had a high loading capacity of DOX (Qe = 159.71 mg∙g−1), and the amount released under acidic conditions (pH 5.0) was greater (63.4 % after 15 h) than under neutral conditions (pH 7.4) due to the detachment of the coordination between metal ions and ligands (37.6 % after 15 h).

Piezoelectric-Enhanced Nanocatalysts Trigger Neutrophil N1 Polarization against Bacterial Biofilm by Disrupting Redox Homeostasis.

Strategies of manipulating redox signaling molecules to inhibit or activate immune signals have revolutionized therapeutics involving reactive oxygen species (ROS). However, certain diseases with dual resistance barriers to the attacks by both ROS and immune cells, such as bacterial biofilm infections of medical implants, are difficult to eradicate by a single exogenous oxidative stimulus due to the diversity and complexity of the redox species involved. Here, this work demonstrates that metal-organic framework (MOF) nanoparticles capable of disrupting the bacterial ROS-defense system can dismantle bacterial redox resistance and induce potent antimicrobial immune responses in a mouse model of surgical implant infection by simultaneously modulating redox homeostasis and initiating neutrophil N1 polarization in the infection microenvironment. Mechanistically, the piezoelectrically enhanced MOF triggers ROS production by tilting the band structure and acts synergistically with the aurintricarboxylic acid loaded within the MOF, which inhibits the activity of the cystathionine γ-cleaving enzyme. This leads to biofilm structure disruption and antigen exposure through homeostatic imbalance and synergistic activation of neutrophil N1 polarization signals. Thus, this study provides an alternative but promising strategy for the treatment of antibiotic-resistant biofilm infections.

Investigating the Size Effect of Metal-Organic Frameworks in Drug Delivery and Anticancer Properties.

Here, we show particle size-dependent therapeutic efficacy with a Zn-based metal-organic framework (MOF). The size of MOFs was tuned in specific ranges (∼100, 200, and 300 nm) built upon the manipulation of synthetic conditions. X-ray photoelectron spectroscopy, infrared, PXRD, and dynamic light scattering and scanning electron microscopy analyses were used to identify the synthesized structures. The various analyses revealed minimal changes in the molecular properties of these structures regardless of their size, confirming our hypothesis regarding the preservation of the identity of MOF nanoparticles despite size variation. The synthesized carriers undergo structure relative destruction in response to a weak acidic tumor microenvironment, and this relative degradation allows the release of the Nimesulide drug into the environment. Interestingly, anticancer studies resulting in SKBR3 (Human breast cancer cell) cells indicate that the different sizes resulted in various inhibition capacities against cancer cells. This work shows the importance of optimizing the geometry of the drug carrier, such as size and shape, to achieve the highest cellular uptake and therapeutic performance. Besides, theoretical studies were carried out using B3LYP/6-31G (d,p) and density functional theory methods to more consider the drug adsorption mechanism.

Highly plasticization-resistant Tröger’s base polymer–MOF mixed-matrix membranes for stable gas separation

The plasticization phenomenon, characterized by polymer chain swelling when exposed to highly soluble gas at high feed pressure, has been a major problem for polymer membranes. To address this, we prepared Tröger’s base (TB) polymer-based metal–organic framework (MOF) mixed-matrix membranes (MMMs), which are highly plasticization-resistant membranes. Three different highly porous MOF nanoparticles (ZIF-8, UiO-66-NH2, and MIL-101(Cr)) were prepared in small particle sizes. The corresponding MMMs were formed with a 30 wt% MOF loading to study the effects of MOF species, particle size, chemical functionality, and MOF–polymer interfacial interaction on gas-transport properties and plasticization behavior. The TB polymer-based MOF MMMs exhibited significantly higher H2 and CO2 permeabilities (fourfold to eightfold) than the TB polymer membrane owing to the porous nature and high gas adsorption capacity of the MOF. Additionally, the TB-based MOF MMMs, particularly the UiO-66-NH2 MMM, displayed exceptional CO2 plasticization resistance. This is attributed to the interfacial interaction of the strong hydrogen bonding between the amine group of the TB polymer and the amino group of UiO-66-NH2, as confirmed by small-angle X-ray scattering characterization. This TB polymer-based MOF MMM approach provides a feasible and effective route for enhancing gas-transport properties and CO2 plasticization resistance to achieve energy-efficient and stable gas separation.

Self‐Assembly of UiO‐66 on Conjugated Polyelectrolytes: Toward Enhanced Photophysical Properties

AbstractIn this study, the synthesis and characterization of the fluorescent metal–organic framework (MOF)‐polymer composites is reported based on zirconium‐based MOFs (UiO‐66 and UiO‐66(OH)₂) and a conjugated polyelectrolyte, poly(phenylene ethynylene) carboxylate (PPE‐CO₂‐108). The defect‐rich nature of these Zr‐MOFs facilitates strong interactions between the polyelectrolyte's carboxylic acid moieties and the open metal sites on the Zr clusters within the MOF nanoparticles. The composites are prepared by a simple impregnation approach, where MOF nanocrystals suspended in HEPES buffer are added to the polymeric solution under sonication for 10 min. The obtained MOF composites (i.e., UiO‐66‐CPE and UiO‐66 (OH)2‐CPE) are characterized using powder X‐ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Brunauer‐Emmett‐Teller (BET) surface area, zeta potential measurements, and UV–vis spectroscopy. The characterization confirmed the homogeneous distribution of the MOF nanocrystals on the polymer as seen in the SEM images, and the interaction with PPE‐CO₂‐108 is confirmed by the decrease in the surface areas from 1050 to 590 m2 g−1 for UiO‐66‐CPE and from 500 to 137 m2 g−1, for UiO‐66(OH)2‐CPE. Fluorescence microscopy revealed strong fluorescence in the microparticles, confirming robust polymer‐MOF interaction. The composites also exhibit improved photostability of the conjugated polyelectrolyte, suggesting their potential for applications in biomedical imaging and other areas requiring stable and bright fluorescent systems.

Performance improvement photodetectors with high speed and detectivity using terbium-doped ZIF-8 and MOF-5 films

Crystal engineering is critical for improving the crystal quality and tuning the optoelectronic properties of metal-organic frameworks (MOFs) materials. Doping MOFs is one of the practical approaches to improve the optoelectronic properties of MOFs. Here, a simple and effective method is used to grow MOF nanoparticles as films on the surface of the material. MOF-5 and ZIF-8 nanoparticles can be uniformly grown as films on the Si substrates. The crystalline quality of MOF films is improved after doping with Tb. Meanwhile, two-dimensional conducting photodetectors and photodetector arrays were prepared with perovskite films. Meanwhile, planar conducting photodetector arrays were prepared with MOF films. The photoluminescence (PL) intensity of the Tb-ZIF-8 and Tb-MOF-5 films shows an improvement compared to both ZIF-8 and MOF-5 layers, which leads to improved charge carriers transfer. The maximum photocurrents were about 4 × 10−8 A and 3 × 10−8 A of exposed light at 525 and 425 nm, respectively, at a fixed bias of 10 V for Tb-ZIF-8. The highest photo response of approximately 2.4 × 10−7 and 1.2 × 10−7 A was measured under 525 and 450 nm for the Tb-MOF-5-based device, respectively. The photocurrent behavior is optimized in the visible range due to the increased number of photo-generated carriers at 525 nm. The Tb-MOF-5 based device is a more powerful photodetector than the Tb-ZIF-8 based device under the same conditions. In addition, the stability of Tb-MOF-5 and Tb-ZIF-8 based photodetectors was obtained 77 % and 30 %, respectively. The photodetectors of Tb-MOF-5 have higher stability and better performance than Tb-ZIF-8.

Effects of Exposure to Different Types of Metal-Organic Framework Nanoparticles on the Gut Microbiota and Liver Metabolism of Adult Zebrafish.

Metal-organic framework nanoparticles (MOF NPs) have received much attention for their potential use in nanopesticides. However, little is known about the potential health and environmental risks associated with these materials. In this study, the toxicological responses of zebrafish exposed to five MOF NPs for short and long periods of time were evaluated. The acute toxicity results showed that the toxicity of the five MOF NPs to zebrafish embryos and adult zebrafish was in the order of Cu-MOF > ZIF-90 > ZIF-8 > Fe-MOF > Zr-MOF. Histopathological analysis revealed that ZIF-8, ZIF-90, and Cu-MOF NPs caused liver swelling and vacuolization in zebrafish. The cellular ultrastructure showed that ZIF-8, ZIF-90, and Cu-MOF NPs severely damaged the mitochondrial structure in intestinal epithelial cells and liver cells. The 16S rDNA sequencing data showed that all five MOF NPs significantly altered the dominant microorganisms in the zebrafish intestine. The microbial markers of intestinal inflammation, Proteobacteria (Aeromonas, Plesiomonas, and Legionella), were significantly increased in the Fe-MOF, ZIF-8, Zr-MOF, and Cu-MOF treatment groups. Metabolomics results indicated that the levels of inflammatory promoting factors (Leukotriene E4, 20-hydroxyeicosatetraenoic acid) in arachidonic acid metabolism were decreased, and the levels of inflammatory suppressing factors (8,9-epoxyeicosatrienoic acid) were increased. Metabolites related to oxidative stress, such as glutamine, pyridoxamine, and l-glutamic acid in vitamin B6 metabolism and other signaling pathways, were significantly reduced. Overall, these results suggest that the different MOF NPs had widely varying toxicity to zebrafish, and further attention should be paid to the toxicity of MOF NPs in the real environment.

The detection of acetone in exhaled breath using gas Pre-Concentrator by modified Metal-Organic framework nanoparticles

Volatile organic compounds (VOCs) from exhaled breath are promising indicators for the diagnostics of human health conditions. However, the composition of breath is rather complex, including water vapors and various tiny amounts of gases and biomarkers. Pre-concentrator plays a significant role in capturing and concentrating target gas in the gas mixture. In this work, the MIL-101 (Cr) nanoparticles are coated with polydimethylsiloxane (PDMS) through physical vapor deposition process to concentrate acetone under high humidity and room temperature. Experimentally, the newly developed material exhibits significant improvement in signal intensity that is 76.3 times greater than a commercial reference material under relative humility of 80 %. The detection range is also proven to be desirable (from 100 ppb to 2500 ppb), capturing the spectrum of acetone concentrations typically found in human exhaled breath. Moreover, following a thermal desorption process, the device demonstrates a high degree of linearity with a coefficient of 0.9956. The modified metal–organic framework materials are made into a flexible thin-film-shape device, that could be embedded in a facemask. The proposed device could meet the critical requirements for sampling, concentrating and detecting of exhaled breath biomarkers, thereby opening a new opportunity as part of the flexible electronic systems on face masks to facilitate quantitative breath analyses.

Size-Dependent Spin Crossover and Bond Flexibility in Metal-Organic Framework Nanoparticles.

Size reduction offers a synthetic route to tunable phase change behavior. Preparing materials as nanoparticles causes drastic modulations to critical temperatures (Tc), hysteresis widths, and the "sharpness" of first-order versus second-order phase transitions. A microscopic picture of the chemistry underlying this size dependence in phenomena ranging from melting to superconductivity remains debated. As a case study with broad implications, we report that size-dependent spin crossover (SCO) in nanocrystals of the metal-organic framework (MOF) Fe(1,2,3-triazolate)2 arises from metal-linker bonds becoming more labile in smaller particles. In comparison to the bulk material, differential scanning calorimetry indicates a ∼ 30-40% reduction in Tc and ΔH in the smallest particles. Variable-temperature vibrational spectroscopy reveals a diminished long-range structural cooperativity, while X-ray diffraction evidence an over 3-fold increase in the thermal expansion coefficients. This "phonon softening" provides a molecular mechanism for designing size-dependent behavior in framework materials and for understanding phase changes in general.

Rational design of continuous and short-range lithium ion pathways based on polydopamine-anchored metal-organic frameworks for all-solid-state electrolytes

The immerging three dimensional (3D) metal-organic framework (MOF)-reinforced composite solid-state electrolytes have attracted great interest because of the enhanced ionic conductivity and mechanical properties. However, the defective spatial arrangement of MOFs restricted by fabrication methodology leads to insufficient lithium ion transport in electrolytes. Herein, a 3D interconnected MOF framework tailored for all-solid-state electrolytes is rationally designed by a universal polydopamine (PDA)-engineered “double-sided tape” strategy. The PDA serves as a double-sided tape, firmly adhering on the special single-layer Nylon grid as well as offering uniform nucleation sites to anchor the metal nodes to ensure continuous growth of well-ordered MOFs. Benefiting from the Lewis acid feature of MOFs and its cage effect toward TFSI−, a fast and homogeneous lithium ion transport can be achieved through the internal channels within neighboring MOFs and the continuous MOFs/polymer interfaces both along the short-range circumferential boundary of Nylon fiber. The resultant composite electrolytes exhibit high lithium ion conductivity and prominent mechanical properties, rendering excellent cyclic stability whether used in coin or pouch cells. This work demonstrates a widely applicable “double-sided tape” strategy for controllable spatial arrangement of MOF nanoparticles on optional substrates, which provides a scalable approach to rationally construct desired lithium ion pathways within composite electrolytes.