Graphene oxide/Cu-MOF-based electrochemical immunosensor for the simultaneous detection of Mycoplasma pneumoniae and Legionella pneumophila antigens in water

The combination of copper-metal organic framework (Cu-MOF) with graphene oxide (GO) has received growing interest in electrocatalysis, energy storage and sensing applications. However, its potential as an electrochemical biosensing platform remains largely unexplored. In this study, we introduce the synthesis of GO/Cu-MOF nanocomposite and its application in the simultaneous detection of two biomarkers associated with lower respiratory infections, marking the first instance of its use in this capacity. The physicochemical properties and structural elucidation of this composite were studied with the support of XRD, FTIR, SEM and electrochemical techniques. The immunosensor was fabricated by drop casting the nanocomposite on dual screen-printed electrodes followed by functionalization with pyrene linker. The covalent immobilization of the monoclonal antibodies of the bacterial antigens of Mycoplasma pneumoniae (M. pneumoniae; M. p.) and Legionella pneumophila (L. pneumophila; L. p.) was achieved using EDC-NHS chemistry. The differential pulse voltammetry (DPV) signals of the developed immunosensor platform demonstrated a robust correlation across a broad concentration range from 1 pg/mL to 100 ng/mL. The immunosensor platform has shown high degree of selectivity against antigens for various respiratory pathogens. Moreover, the dual immunosensor was successfully applied for the detection of M. pneumoniae and L. pneumophila antigens in spiked water samples showing excellent recovery percentages. We attribute the high sensitivity of the immunosensor to the enhanced electrocatalytic characteristics, stability and conductivity of the GO-MOF composite as well as the synergistic interactions between the GO and MOF. This immunosensor offers a swift analytical response, simplicity in fabrication and instrumentation, rendering it an appealing platform for the on-field monitoring of pathogens in environmental samples.

Synthesis of Nanosized γ-Cyclodextrin Metal-Organic Frameworks as Carriers of Limonene for Fresh-Cut Fruit Preservation Based on Polycaprolactone Nanofibers

To address the issue of bacterial growth on fresh-cut fruits, this paper reports the synthesis of nanosized γ-cyclodextrin metal-organic frameworks (CD-MOFs) using an ultrasound-assisted method and their application as carriers of limonene for antibacterial active packaging. The effects of the processing parameters on the morphology and crystallinity of the CD-MOFs are investigated, and the results prove that the addition of methanol is the key to producing nanosized CD-MOFs. The limonene loading content of the nanosized CD-MOFs can reach approximately 170 mg g-1. The sustained-release behaviors of limonene in the CD-MOFs are evaluated. Molecular docking simulations reveal the distribution and binding sites of limonene in the CD-MOFs. CD-MOFs are deposited on the surfaces of polycaprolactone (PCL) nanofibers via an immersion method, and limonene-loaded CD-MOF@PCL nanofibers are prepared. The morphology, crystallinity, thermal stability, mechanical properties, and antibacterial activity of the nanofibers are also studied. The nanofiber film effectively inhibits bacterial growth and prolongs the shelf life of fresh-cut apples. This study provides a novel strategy for developing antibacterial active packaging materials based on CD-MOFs and PCL nanofibers.

Unveiling the potential of HKUST-1: synthesis, activation, advantages and biomedical applications

Metal-organic frameworks (MOFs) have emerged as a unique class of nanostructured materials, resulting from the self-assembly of metal ions or clusters with organic ligands, offering a wide range of applications in fields such as drug delivery, gas catalysis, and electrochemical sensing. Among them, HKUST-1, a copper-based MOF, has gained substantial attention due to its remarkable three-dimensional porous structure. Comprising copper ions and benzene-1,3,5-tricarboxylic acid, HKUST-1 exhibits an extraordinary specific surface area and pronounced porosity, making it a promising candidate in biomedicine. Notably, the incorporation of copper ions endows HKUST-1 with noteworthy activities, including antitumor, antibacterial, and wound healing-promoting properties. In this comprehensive review, we delve into the various synthesis methods and activation pathways employed in the preparation of HKUST-1. We also explore the distinct advantages of HKUST-1 in terms of its structural properties and functionalities. Furthermore, we investigate the exciting and rapidly evolving biomedical applications of HKUST-1. From its role in tumor treatment to its antibacterial effects and its ability to promote wound healing, we showcase the multifaceted potential of HKUST-1 in addressing critical challenges in biomedicine.

A Series of Novel 3D Coordination Polymers Based on the Quinoline-2,4-dicarboxylate Building Block and Lanthanide(III) Ions-Temperature Dependence Investigations

A series of novel 3D coordination polymers [Ln2(Qdca)3(H2O)x]·yH2O (x = 3 or 4, y = 0-4) assembled from selected lanthanide ions (Ln(III) = Nd, Eu, Tb, and Er) and a non-explored quinoline-2,4-dicarboxylate building block (Qdca2- = C11H5NO42-) were prepared under hydrothermal conditions at temperatures of 100, 120, and 150 °C. Generally, an increase in synthesis temperature resulted in structural transformations and the formation of more hydrated compounds. The metal complexes were characterized by elemental analysis, single-crystal and powder X-ray diffraction methods, thermal analysis (TG-DSC), ATR/FTIR, UV/Vis, and luminescence spectroscopy. The structural variety of three-dimensional coordination polymers can be ascribed to the temperature effect, which enforces the diversity of quinoline-2,4-dicarboxylate ligand denticity and conformation. The Qdca2- ligand only behaves as a bridging or bridging-chelating building block binding two to five metal centers with seven different coordination modes arising mainly from different carboxylate group coordination types. The presence of water molecules in the structures of complexes is crucial for their stability. The removal of both coordinated and non-coordinated water molecules leads to the disintegration and combustion of metal-organic frameworks to the appropriate lanthanide oxides. The luminescence features of complexes, quantum yield, and luminescent lifetimes were measured and analyzed. Only the Eu complexes show emission in the VIS region, whereas Nd and Er complexes emit in the NIR range. The luminescence properties of complexes were correlated with the crystal structures of the investigated complexes.

Construction of Cu-BTC by carboxylic acid organic ligand and its application in low temperature SCR denitration

The removal of NO has always been a hot issue in the treatment of coal-fired flue gas. In this paper, a hydrothermal synthesis method was used to prepare porous denitration catalysts with polycarboxyl organic isomers (trimellitic acid, phthalic acid, and benzoic acid). And then developed as the NO removing catalysts for low temperature selective catalytic reduction (SCR) with NH₃. XRD, BET, SEM, FTIR, XPS, Raman, H₂-TPR, NH₃-TPD and TG were used to analyze the crystallinity, microscopic morphology, surface functional groups and metal content. The results showed that: (1) From the crystal structure analysis, the catalyst prepared with 1,3,5 and 1,2,4-benzenetricarboxylic acid as ligands (1,3,5-A and 1,2,4-B) was Cu-BTC. (2) 1,3,5-A catalyst had a huge specific surface area, up to 1421.32 m²/g, and a pore volume up to 0.5798 cm³/g. (3) The prepared catalysts were applied to NH₃-SCR denitration, and the catalyst with Cu-BTC structure had relatively high catalytic performance, and the overall catalytic capacity showed an increasing trend with the temperature. (4) 1,3,5-A catalyst had stability and catalytic activity. When the temperature was 270 °C, the denitration efficiency reached 83.87%. And within 8 h, the denitration efficiency was stable up to 82%.

Adsorptive removal of methylene blue dye from aqueous streams using photocatalytic CuBTC/ZnO chitosan composites

In this study, a CuBTC/ZnO chitosan composite was synthesized for the adsorptive removal of methylene blue dye from aqueous streams. Characterization techniques, namely, scanning electron microscopy, Brunauer-Emmett-Teller, Fourier transform infrared, X-ray diffraction, and thermogravimetric techniques, were used to characterize CuBTC, ZnO, and CuBTC/ZnO chitosan composites. The scanning electron microscopy images revealed the rough and porous structures of the CuBTC/ZnO chitosan composite. The composites were tested for the adsorption capacity and removal efficiency towards the methylene blue dye by varying adsorbent dosage, adsorbate concentration, pH, and contact time. The pseudo-second-order and Langmuir models were the best fit for the adsorption of methylene blue on CuBTC/ZnO chitosan composite beads, indicating that the adsorption was monolayer and chemical in nature. The equilibrium dose of the composites was 1.6 g L^-1, and the contact time was 90 min with a removal efficiency of 98.75%. The maximum adsorption capacity was 50.07 mg g^-1. Regeneration of the composites was performed to check the reusability of the synthesized CuBTC/ZnO chitosan composite beads. The active oxygenated species generated by the photocatalytic action of ZnO on the contaminated water was responsible for the degradation of methylene blue. The reported composite beads can be used for up to 5 cycles to remove methylene blue.

Natural Wood-Based Catalytic Membrane Microreactors for Continuous Hydrogen Generation

The development of controlled processes for continuous hydrogen generation from solid-state storage chemicals such as ammonia borane is central to integrating renewable hydrogen into a clean energy mix. However, to date, most reported platforms operate in batch mode, posing a challenge for controllable hydrogen release, catalyst reusability, and large-scale operation. To address these issues, we developed flow-through wood-based catalytic microreactors, characterized by inherent natural oriented microchannels. The prepared structured catalysts utilize silver-promoted palladium nanoparticles supported on metal-organic framework (MOF)-coated wood microreactors as the active phase. Catalytic tests demonstrate their highly controllable hydrogen production in continuous mode, and by adjusting the ammonia borane flow and wood species, we reach stable productivities of up to 10.4 cm_H2³ min^-1 cm_cat^-3. The modular design of the structured catalysts proves readily scalable. Our versatile approach is applicable for other metals and MOF combinations, thus comprising a sustainable and scalable platform for catalytic dehydrogenations and applications in the energy-water nexus.

A series of four novel alkaline earth metal-organic frameworks constructed of Ca(ii), Sr(ii), Ba(ii) ions and tetrahedral MTB linker: structural diversity, stability study and low/high-pressure gas adsorption properties

A series of four novel microporous alkaline earth metal–organic frameworks (AE-MOFs) containing methanetetrabenzoate linker (MTB) with composition {[Ca₄(μ₈-MTB)₂]·2DMF·4H₂O}_n (UPJS-6), {[Ca₄(μ₄-O)(μ₈-MTB)_3/2(H₂O)₄]·4DMF·4H₂O}_n (UPJS-7), {[Sr₃(μ₇-MTB)_3/2]·4DMF·7H₂O}_n (UPJS-8) and {[Ba₃(μ₇-MTB)_3/2(H₂O)₆]·2DMF·4H₂O}_n (UPJS-9) (UPJS = University of Pavol Jozef Safarik) have been successfully prepared and characterized. The framework stability and thermal robustness of prepared materials were investigated using thermogravimetric analysis (TGA) and high-energy powder X-ray diffraction (HE-PXRD). MOFs were tested as adsorbents for different gases at various pressures and temperatures. Nitrogen and argon adsorption showed that the activated samples have moderate BET surface areas: 103 m² g⁻¹ (N₂)/126 m² g⁻¹ (Ar) for UPJS-7′′, 320 m² g⁻¹ (N₂)/358 m² g⁻¹ (Ar) for UPJS-9′′ and UPJS-8′′ adsorbs only a limited amount of N₂ and Ar. It should be noted that all prepared compounds adsorb carbon dioxide with storage capacities ranging from 3.9 to 2.4 wt% at 20 °C and 1 atm, and 16.4–13.5 wt% at 30 °C and 20 bar. Methane adsorption isotherms show no adsorption at low pressures and with increasing pressure the storage capacity increases to 4.0–2.9 wt% of CH₄ at 30 °C and 20 bar. Compounds displayed the highest hydrogen uptake of 3.7–1.8 wt% at −196 °C and 800 Torr among MTB containing MOFs.

Four novel microporous alkaline earth metal–organic frameworks (AE-MOFs) containing methanetetrabenzoate linker (MTB): UPJS-6, UPJS-7, UPJS-8 and UPJS-9 have been successfully prepared, characterized and tested as adsorbents for different gases.

Topological polymorphism and temperature-driven topotactic transitions of metal–organic coordination polymers

A facile crystal-to-crystal solid-state phase transition between a low-temperature phase and a high temperature phase changes the MOF topology and involves a significant rearrangement of bulky organic ligands.

Cu-BTC Metal−Organic Framework Modified Membranes for Landfill Leachate Treatment

In this study, Cu-BTC (copper(II) benzene-1,3,5-tricarboxylate) metal-organic frameworks (MOFs) were incorporated into the structure of polysulfone (PSf) ultrafiltration (UF) membranes to improve the membrane performance for landfill leachate treatment, whereby different concentrations of Cu-BTC (0.5, 1, 1.5, 2 wt%) were added to the PSf casting solution. The successful incorporation of Cu-BTC MOFs into the modified membranes was investigated by field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX). The Cu-BTC-modified PSf membranes showed higher performance in terms of flux and rejection, as compared to the neat PSf membrane. For example, the pure water flux (PWF) of neat membrane increased from 111 to 194 L/m2h (LMH) by loading 2 wt% Cu-BTC into the membrane structure, indicating 74% improvement in PWF. Furthermore, the flux of this membrane during filtration of landfill leachate increased up to 15 LMH, which indicated 50% improvement in permeability, as compared to the neat membrane. Finally, the modified membranes showed reasonable antifouling and anti-biofouling properties than the blank membrane.

Improved Chloride Ion Sensing Performance of Flexible Ag-NPs/AgCl Electrode Sensor Using Cu-BTC as an Effective Adsorption Layer

We designed the flexible chloride ion selective sensor that directly monitors electrochemical reactions of chloride ions without using a reference electrode. A flexible polytetrafluoroethylene (PTFE) substrate was utilized to provide bendability to the fabricated sensor. As an ion selective material, Ag nanoparticles were employed on the MWCNTs loaded on the PTFE substrate. Enhanced adsorption property of the fabricated sensor toward the chloride ions was given by incorporation of hydrophilic copper benzene-1,3,5-tricarboxylate (Cu-BTC) with great flexibility and stability. Accordingly, compared to the bare sensor the sensing performance of the Cu-BTC treated Ag NPs/AgCl electrode sensor was improved by indicating the decrease in response and recovery time about 4 times. It elucidated that the Cu-BTC layer could work as an effective medium between the Ag-NPs surface and electrolyte containing chloride ions. As a result of contact angle measurement, the hydrophilicity much increased in the Cu-BTC treated sensor because the exposed surface of the sensor not treated by the Cu-BTC largely consisted of hydrophobic MWCNTs. Furthermore, the Cu-BTC layer could hold the electrolyte for effective adsorption of analytes with large specific surface area.

Pd Nanoparticles and MOFs Synergistically Hybridized Halloysite Nanotubes for Hydrogen Storage

Natural halloysite nanotubes (HNTs) were hybridized with metal-organic frameworks (MOFs) to prepare novel composites. MOFs were transformed into carbon by carbonization calcination, and palladium (Pd) nanoparticles were introduced to build an emerging ternary compound system for hydrogen adsorption. The hydrogen adsorption capacities of HNT-MOF composites were 0.23 and 0.24 wt%, while those of carbonized products were 0.24 and 0.27 wt% at 25 °C and 2.65 MPa, respectively. Al-based samples showed higher hydrogen adsorption capacities than Zn-based samples on account of different selectivity between metal and hydrogen and approximate porous characteristics. More pore structures are generated by the carbonization reaction from metal-organic frameworks into carbon; high specific surface area, uniform pore size, and large pore volume benefited the hydrogen adsorption ability of composites. Moreover, it was also possible to promote hydrogen adsorption capacity by incorporating Pd. The hydrogen adsorption capacity of ternary compound, Pd-C-H3-MOFs(Al), reached 0.32 wt% at 25 °C and 2.65 MPa. Dissociation was assumed to take place on the Pd particles, then atomic and molecule hydrogen spilled over to the structure of carboxylated HNTs, MOFs, and the carbon products for enhancing the hydrogen adsorption capacity.

Facile room temperature synthesis of metal–organic frameworks from newly synthesized copper/zinc hydroxide and their application in adsorptive desulfurization

Facile synthesis of metal–organic frameworks was demonstrated via directly adding organic ligands solution into the newly synthesized copper/zinc hydroxide solution.

The impact of MOF feasibility to improve the desalination performance and antifouling properties of FO membranes

In this study, a hydrophilic metal–organic framework (MOF) was applied to improve the performance of a cellulosic membrane for forward osmosis (FO) desalination application.

The structure of a coordination polymer constructed of manganese(II) biphenyl-4, 4′-dicarboxylate

Manganese(II) biphenyl-4,4′-dicarboxylate, prepared by crystallization of a mixture of biphenyl-4,4′- dicarboxylic acid, manganese(II) chloride, and di(4-pyridyl)acetylene as base in a mixture of dimethylformamide, ethanol and water in a closed vessel at elevated temperatures forms a 3D network of {[Mn(bpdc)(H2O)2][Mn(bpdc)(H2O)]} containing one five-fold coordinated and one six-fold coordinated Mn metal center (X-ray structure determination). Scanning tunneling microscopic (STM) measurements of manganese biphenyl-4,4′-dicarboxylate adsorbed on highly oriented pyrolytic graphite showed strands, the averaged diameter of which amounts to 18±1 nm, whereas the apparent height is about 0.5±0.02 nm.

Turn-on luminescence based discrimination of protic acids using a flexible layered metal–organic coordination polymer

A flexible layered metal–organic coordination polymer used as probe for turn-on luminescence based discrimination of protic acids and amino acids.