Silver-based Metal-organic Framework Research Articles

Preparation of silver-based metal-organic framework and chitosan hybrid material for removing drug and dye

Pharmaceuticals and personal care products and dyes have low biodegradability and high toxicity, seriously threaten the human health and ecological environment. Therefore, seeking effective removal methods has become the focus of research. In this study, silver-based metal-organic framework (Ag-MOF) and chitosan (CS) hybrid adsorbent (Ag-MOF-CS) was synthesized via solvothermal one-pot synthesis to remove diclofenac sodium (DCF) and acid Red 1 (AR1) from water for the first time. The morphology and structure of Ag-MOF-CS were confirmed by various characterizations. The effect on adsorption was investigated by changing the adsorbent dosage, pH and other conditions. The adsorption kinetics, adsorption isotherms and thermodynamics were analyzed. Ag-MOF-CS showed a high adsorption capacity. And the maximum adsorption capacity of Ag-MOF-CS for DCF and AR1 was 351.75 mg/g and 678.83 mg/g, respectively. The adsorbent bound to DCF and AR1 may via electrostatic forces, π-π interactions, hydrogen bonding. Even after four cycles of Ag-MOF-CS, the DCF removal can still be higher than 80 %. The eco-friendly Ag-MOF-CS demonstrated significant potential for utilization in treating wastewater.

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.

A label-free aptasensor based on electrodeposition of gold nanoparticles on silver-based metal-organic frameworks for measuring ochratoxin A in black and red pepper.

Since ochratoxin A (OTA) is immunotoxic, teratogenic and carcinogenic, it is very important to monitor this compound in food samples. In the present work, the development and fabrication of a label-free electrochemical aptasensor based on the gold nanoparticles/silver-based metal-organic framework (AuNPs/Ag-MOF) for the determination of ochratoxin A (OTA) is introduced. The aptasensor was fabricated by electrodeposition of AuNPs on a glassy carbon electrode modified with Ag-MOF. The characteristics of the synthesized Ag-MOF were determined by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and UV-Visible spectroscopy. The aptamer was immobilized on the modified electrode and then OTA was incubated on it. The process of different stages of the aptasensor construction has been confirmed by two methods of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) and using [Fe(CN)6]3-/4- as a redox probe. The EIS method has also been used for the OTA quantitative determination. The difference in charge transfer resistance (Rct) before and after the interaction of OTA with the immobilized aptamer was considered as the analytical response of the aptasensor. Using the developed aptasensor, it is possible to measure OTA in the concentration range of 1.0 × 10-3 to 200.0 ng mL-1 with a detection limit of 2.2 × 10-4 ng mL-1. Finally, the ability of the aptasensor to measure OTA in red and black pepper was investigated and completely satisfactory results were obtained.

A sensitive electrochemical sensor for glutathione based on specific recognition induced collapse of silver-contained metal organic frameworks.

An electrochemical sensor capable of detecting glutathione (GSH) with high sensitivity and selectivity was developed based on the unique novel electroactive silver-based metal organic framework (Ag-MOF). The Ag-MOF obtained by silver nitrate and 1,3,5-benzoic acid (H3BTC) was thoroughly characterized and was modified onto the electrode via facile drop-casting method. The electrochemical response of GSH on the Ag-MOF modified electrode showed a significant reduction in the current signal because the Ag-GSH complex had stronger specific affinity than Ag-H3BTC and resulted in the collapse of the Ag-MOF. This sensor demonstrated an extensive linear dynamic range of 0.1 nM-1 µM, along with the low detection limit of 0.018 nM. Additionally, it exhibited good reproducibility, stability, and resistance to interfering compounds. The Ag-MOF modified electrode demonstrated superior performance attributed to its rapid electron transfer rate, outstanding electrochemical redox activity, and specific recognition/competitive reaction. These factors improved both sensitivity and selectivity. The high anti-interference ability allowed for the selective detection of GSH in intricate surroundings. In the real sample testing, the RSD was lower than 3.1% and the recovery was between 98.1 and 103%. This research highlights the potential of Ag-MOFs in developing electrochemical sensors and their promising applications in determining GSH for food screening and early disease diagnosis.

Responsive luminescent silver-based metal-organic frameworks for highly sensitive and selective detection of hydrogen sulfide in biological system via a self-assembled headspace separation device

As a highly toxic gas pollutant and also an endogenous gaseous signaling molecule existing in a variety of physiological processes, the rapid and accurate in-field detection of hydrogen sulfide is of great concern. Nevertheless, two drawbacks as for the optical probes for H2S detection, taking about a long time to reach the optical signal balance or the low selectivity, always exist. Herein, by using a highly photoluminescent and H2S-stimuli responsive silver-based metal-organic frameworks (MOFs): Ag-BDC (BDC = 1, 4-benzene dicarboxylate), we demonstrated that the luminescence intensity of Ag-BDC MOFs was inversely proportional to the concentration of H2S due to the Ag–S coordination and the obstruction of ligand-to-metal charge transfer (LMCT) transition process, and there was a quick response time of below 3.0 min. Combined with a simple customized device to separate H2S from the sample, the selectivity of the method for H2S detection could be greatly improved, and no interference would be caused even if the other sulfur-containing species coexisted. The luminescence probe presented a favorable sensitivity within a linear range of 0.1–1000 μM along with a detection limit of 23.7 nM. When employed to assay the endogenous sulfide level in the human serum and mouse brain tissue, the approach showed recoveries from 96.3% to 102% with relative standard derivation (RSD) less than 2.0%. By the integration of the responsive luminescent silver-based MOFs with a simple self-assembled headspace separation device, obviously the present strategy could be beneficial to the development and design of the in-field fast H2S measurement, possessing particular advantages in biological systems to eliminate the potential interferences.

Application of Metal-Organic Frameworks for Efficient Removal of Doxorubicin Hydrochloride: Removal Process Optimization and Biological Activity.

This study looked at the doxorubicin hydrochloride (DOX) anticancer drug's adsorption characteristics on a silver-based metal-organic framework (Ag-MOF). X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used for the characterization of Ag-MOF. The pore volume and surface area of Ag-MOF were determined through Brunauer-Emmett-Teller (BET) testing at 77 K to be 0.509 cm3/g and 676.059 m2/g, respectively. Adsorption at pH 6 was established to be the best for DOX compared to alkaline solution. Ag-MOF has a good capacity for eliminating DOX (1.85 mmol/g), according to adsorption experiments. From the adsorption results, we can find that Langmuir is the most fitted adsorption isotherm model and the pseudo-second order model best fitted the adsorption kinetics. The energy of activation for adsorption, which was determined to be 15.23 kJ/mol, also supported a chemisorption process. The mechanism of adsorption was evaluated, and details of all possible interactions between DOX and Ag-MOF were illustrated. On the other hand, while examining the impact of temperature, we identified the thermodynamic constraints as ΔG°, ΔH°, and ΔS° and confirmed that the reaction was an endothermic one and spontaneous. Even after numerous reuse cycles, the efficiency remained constant. The synthetic adsorbent was remarkably recyclable at a rate of more than 91.6%. By using the MTT assay, the cytotoxicity of the tested Ag-MOF and DOX@Ag-MOF against human breast cancer cells (MCF-7) was evaluated in vitro. The in vitro antimicrobial activity of Ag-MOF and DOX@Ag-MOF was also tested.

A comprehensive study on a novel chitosan/Ag-MOFs nanocomposite coatings for bone implants: Physico-chemical, biological and electrochemical properties

The present study developed new multi-functional coatings made of novel silver-based metal-organic frameworks (SOF) distributed within chitosan (CS) nanofibers network for bone implants. The SOFs were synthesized using environmental-friendly materials via a green process. The CS-SOF nanocomposites were deposited on novel hierarchical etched (HE) layers synthesized through a dual surface treatment. In vitro biological evaluation revealed appropriate biocompatibility for the prepared surfaces. Antimicrobial tests exhibited 100-200% effective antibacterial activities along with significant reduction of bacterial colonies. Electron microscopy illustrated proper cell attachment and growth on the multilayer HE/CS-SOF coatings. The designed surfaces exhibited great apatite formation capability and superior bone bioactivity. Electrochemical studies demonstrated that all surface treatments, shifted the corrosion potential of the titanium substrate to the nobler potentials. The HE/CS-0.50SOF coating showed the noblest corrosion potential of ∼62.4 mV (vs. SCE). Passivation current density of the titanium surface decreased more than 99% using the HE/CS-0.50SOF coating. The corrosion resistance of the HE/CS-SOF nanocomposite coatings improved more than 99% by increasing the SOFs concentration. Charge transfer resistance of the HE/CS-SOF nanocomposites improved more than 630% by increasing the SOFs concentration. The results proved that the produced coatings can be promising candidates for biomedical applications.

Synthesis of Novel Bacterial Cellulose Based Silver-Metal Organic Frameworks (BC@Ag-MOF) as Antibacterial Wound Healing

Bacterial Cellulose (BC) is a polymer derived from the bacterium Komagataeibacter xylinus with great potential for biomedical applications due to its high biocompatibility and biodegradability. In addition, the polymer is naturally biosynthesized by bacteria as hydrogels which can be used as optimal substrates for wound healing. However, the drawback of BC is the absence of antibacterial properties. Nowadays, some infections become more prevalent and harder to treat because of antimicrobial resistance, therefore, it is necessary to develop a strategy for modifying BC as wound healing that provides protection against bacterial contamination. In this work, silver-based Metal Organic Frameworks (MOFs) were immobilized into Bacterial Cellulose (BC). MOFs are porous coordination materials consisting of metal ions and multidentate organic ligands that have the potential as a matrix for metal ions due to their ability to gradually release metal ions. The structure and morphology of BC@Ag-MOF were successfully confirmed by Fourier-Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscope (SEM). Evidently, BC@Ag-MOF exhibited a higher silver content (63.19%) than BC@Ag without immobilization into MOF (48.46%). Therefore, it indicated that MOF has large pores for enhancing the capacity for silver ion absorption in BC. The modified BC has never been reported and achieved the highest antibacterial activity of 99.99% against Gram-negative bacteria Escherichia coli. Moreover, BC@Ag-MOF has a higher antibacterial efficiency of 97% compared to BC@Ag without matrix. This study expands the potential application of BC modification in the field of biological antibacterial. has never been reported and achieved the highest antibacterial activity of 99.99% against Gram-negative bacteria Escherichia coli. Moreover, BC@Ag-MOF has a higher antibacterial efficiency of 97% compared to BC@Ag without matrix. This study expands the potential application of BC modification in the field of biological antibacterial.

A Novel Silver-Based Metal-Organic Framework Incorporated into Nanofibrous Chitosan Coatings for Bone Tissue Implants

In this work, new multi-layer nanocomposite coatings comprised of chitosan (CS) nanofibers functionalized using an innovative silver-based metal–organic framework (SOF) were developed. The SOFs were produced via a facile process using green and environmental-friendly materials. The CS-SOF nanocomposites were coated on hierarchical oxide (HO) layers fabricated on titanium substrates by an innovative two-step etching process. X-ray diffraction revealed fruitful production of the SOF NPs and their stable crystalline structure within the nanocomposite coatings. Energy-dispersive x-ray spectroscopy approved uniform SOFs distribution in the CS-SOF nanocomposites. Atomic force microscopy indicated more than 700% increased nanoscale roughness for the treated surfaces compared to the bare sample. In vitro MTT assay revealed proper cell viabilities on the samples, however, high SOFs concentration led to less biocompatibility. All coatings demonstrated positive cell proliferation rates up to 45% after 72 h. Antibacterial studies showed significant inhibition zones against Escherichia coli and Staphylococcus aureus bacteria with 100–200% effective antibacterial activities. Electron microscopy exhibited excellent cell-implant integration for the CS-SOF nanocomposite surfaces due to the attached cells with expanded morphologies and long filopodia. The prepared coatings showed high apatite formation capability and bone bioactivity.

AgBTC MOF-Mediated Approach to Synthesize Silver Nanoparticles Decorated on Reduced Graphene Oxide (rGO@Ag) for Energy Storage Applications

Nanowires of silver-based metal–organic framework (MOF) (AgBTC, BTC = 1,3,5-benzenetricarboxylate) were grown onto graphene oxide layers to generate GO-AgBTC nanocomposites. Thermal treatment of these composites in inert atmosphere produced reduced graphene oxide (rGO) decorated with well-dispersed and homogeneous silver nanoparticles (rGO@Ag). The easy and scalable synthesis of AgNPs via MOF-mediated synthesis was achieved by the thermal decomposition of the AgBTC directly onto the rGO surface. The structure, morphology, and electrochemical properties of this novel material were investigated by XRD, Raman, TGA, FE-SEM, TEM, cyclic voltammetry, and galvanostatic charge and discharge experimental techniques. The results showed improved capacitive features for rGO@Ag. Specific gravimetric capacitance measured by galvanostatic charge–discharge yielded a value of 151.97 F/g at the current density of 0.5 A/g, pointing out that MOF-mediated synthesis offers a facile method to generate rGO electrodes decorated by uniformly distributed nanoparticles for energy storage devices.

Antiadherent AgBDC Metal-Organic Framework Coating for Escherichia coli Biofilm Inhibition.

Surface microbial colonization and its potential biofilm formation are currently a major unsolved problem, causing almost 75% of human infectious diseases. Pathogenic biofilms are capable of surviving high antibiotic doses, resulting in inefficient treatments and, subsequently, raised infection prevalence rates. Antibacterial coatings have become a promising strategy against the biofilm formation in biomedical devices due to their biocidal activity without compromising the bulk material. Here, we propose for the first time a silver-based metal-organic framework (MOF; here denoted AgBDC) showing original antifouling properties able to suppress not only the initial bacterial adhesion, but also the potential surface contamination. Firstly, the AgBDC stability (colloidal, structural and chemical) was confirmed under bacteria culture conditions by using agar diffusion and colony counting assays, evidencing its biocide effect against the challenging E. coli, one of the main representative indicators of Gram-negative resistance bacteria. Then, this material was shaped as homogeneous spin-coated AgBDC thin film, investigating its antifouling and biocide features using a combination of complementary procedures such as colony counting, optical density or confocal scanning microscopy, which allowed to visualize for the first time the biofilm impact generated by MOFs via a specific fluorochrome, calcofluor.

Terbium-functionalized silver-based metal-organic frameworks for efficient antibacterial and simultaneous monitoring of bacterial spores

Effective sterilization and timely monitoring of bacterial spores are critical to addressing the safety concerns in the environment. Here, we design and synthesize two silver-based metal-organic frameworks Ag-tpt (Htpt=5-[4(1H-1,2,4-triazol-1-yl)]phenyl-2H-tetrazole) and Ag-tmpt (Htmpt=5-(4-((1H-1,2,4-triazol-1-yl)methyl)phenyl)-1H-tetrazole) with excellent antibacterial activity against Bacillus subtilis (B. subtilis) and Escherichia coli (E. coli), respectively. The Ag-tpt with an increased degree of conjugation exhibits high stability and enhanced fluorescence performance. Furthermore, the ratiometric fluorescence probe Tb3+@Ag-tpt is fabricated for detecting dipicolinic acid (DPA) in the aqueous solution, showing quite a competitive detection range (0–65 µM) and a low detection limit (LOD = 24.2 nM). In addition, the Tb3+@Ag-tpt presents a low LOD of bacterial spores (1.9 × 104 spores/mL) and also inherits the excellent antibacterial function against B. subtilis and E. coli, in which the antibacterial circle diameters reached 20.8 ± 0.8 mm and 22.3 ± 0.6 mm, respectively. Therefore, the silver-based composite materials bring broad prospects in the fields of reducing bacterial contamination and detecting bacterial spores in real time.

Improved biological activities of dual nanofibrous chitosan/bacterial cellulose wound dressing by a novel silver-based metal-organic framework

The worldwide menace of antibiotic-resistance bacteria could be weakened by development and utilization of impressive and multi-functional bactericidal materials. In this work, a novel silver-based metal-organic framework (SOF) was synthesized via a facile and environmentally-friendly process. Different amounts of the SOF nanoparticles incorporated in dual nanosized chitosan/bacterial cellulose (CS/BC) fibrous composites to make a hybrid antibacterial porous structure for mimicing the skin extracellular matrix. X-ray diffraction revealed the successful synthesis of the SOF and CS/BC-SOF nanocomposites using green solvents at ambient temperature. Energy-dispersive X-ray spectroscopy confirmed the presence of Ag species in the SOF structures. Electron microscopy images showed ∼30 nm nanofibers of the CS/BC blend embedded with uniform distribution of the SOF nanoparticles. MTT assay demonstrated the best biocompatibility performance with cell viability of ∼94% for the CS/BC-25%SOF nanocomposite. Antibacterial tests indicated adequate and efficient antibacterial activity of all SOF-containing samples against E. coli and S. aureus strains. Animal in vivo studies demonstrated excellent healing with ∼74% wound closure for the wounds treated using CS/BC-25%SOF nanocomposite during the 2nd week after surgery. Hematoxylin and eosin staining revealed successful healing and tissue regeneration for the wounds treated using CS/BC-25%SOF nanocomposite. The results suggest that the new produced nanocomposites, especially the CS/BC-25%SOF, can potentially be used as excellent platforms for wound dressing.

An electrochemiluminescence aptasensor based on highly luminescent silver-based MOF and biotin-streptavidin system for mercury ion detection.

In this study, for the first time, a silver-based metal-organic framework (Ag-MOF) was synthesized and used as the electrochemiluminescence (ECL) emitter for building an ECL sensor. After modification with chitosan (CS) and gold nanoparticles (Au NPs), the ECL stability of Ag-MOF was improved. To detect mercury ions, a biosensor was constructed using the mercury ion aptamer and steric effect of streptavidin. First, the capture strand (cDNA) with terminal-modified sulfhydryl group was attached to the electrode surface by the Au-S bond. Then, the mercury-ion aptamer (Apt-Hg) modified with biotin was anchored to the electrode by complementary pairing with cDNA. Streptavidin (SA) could be fixed on the electrode by linking with biotin, thereby reducing the ECL signal. However, in the presence of mercury ions, the aptamer was removed and streptavidin could not be immobilized on the electrode. Hence, the ECL signal of the sensor increased with the concentration of mercury ions, which was linear in the range from 1 μM to 300 fM. The detection limit could reach 66 fM (S/N = 3). The sensor provided a new method for the detection of mercury ions.

One-Pot Synthesis of Degradable and Renewable Cellulose-Based Packaging Films

Among all of the plastic pollutants, cling packaging films pose a particularly complex problem due to their high consumption, poor reusability, difficulty in recycling, and nondegradability. Despite many efforts by researchers to develop alternatives to plastic cling films, none of the alternatives have been satisfactory. Here, cellulose-based active packaging films that are degradable, renewable, and reusable were prepared by one-pot green synthesis of silver-based metal–organic frameworks on carboxymethyl cellulose (Ag-2MI@CMC). The preparation process is simple (water solvent system with normal temperature and normal pressure). The Ag-2MI@CMC composite film exhibits better performance than commercial PE films, including (1) better mechanical properties and antifog performance, Ag-2MI@CMC film has a high tensile strength of about 61 MPa, while that of commercial PE films is only about 35 MPa, (2) excellent antimicrobial properties, including bacteria and mold, while commercial PE films did not exhibit any antibacterial properties, (3) better fruit preservation than commercial PE cling films, (4) high natural degradability (complete degradation takes only about 45 days, during which time the commercial PE film does not degrade at all), and (5) renewable and reusable more than five times, the recycled Ag-2MI@CMC film still maintains good mechanical strength and fruit preservation effect. Given the low raw material cost and superior performance of the composite film, one-pot green synthesis of cellulose-based active packaging films may be a suitable solution to solve the environmental challenges brought by the high volume of the plastic packaging films.

The anticancer properties of metal-organic frameworks and their heterogeneous nanocomposites.

Herein, silver-based metal-organic framework (AgMOF) and its graphene oxide (GO)-decorated nanocomposite (GO-AgMOF) are proposed for use in emerging biomedical applications. The nanocomposites are characterized, and hence, in vitro apoptotic and antibacterial features of AgMOF and GO-AgMOF nanomaterials were investigated. An MTT cytocompatibility assay indicates that these nanomaterials have dose-dependent toxicity in contact with SW480, colon adenocarcinoma cells. In addition, the cell death mechanism was explored by analyzing flow cytometry and caspase activity. Furthermore, the expressions of pro-apoptotic and anti-apoptotic genes were investigated using quantitative polymerase chain reaction (qPCR). Comparing the control group with the groups treated by the nanomaterials indicates up-regulation of the BAX/BCl2 ratio. We also measured the minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) of these nanomaterials acting on S. mutans and S. aureus, which indicates excellent antibacterial properties. Showing inhibition effect on the viability of cancerous cells through apoptosis and antibacterial effects simultaneously, AgMOF and GO-AgMOF can be regarded as potential therapeutics for cancer.

An ultrasonic-assisted rapid approach for sustainable fabrication of antibacterial and anti-biofouling membranes via metal-organic frameworks

Biofouling is a pivotal problem for polymeric membranes used in water treatment and reuse. Surface functionalization is a promising practice to improve the resistance of membranes to biofouling. Diverse materials, synthesis methods, and functionalization techniques will be needed to address different applications. Herein, we employed a novel ultrasonic-assisted technique to functionalize polyvinylidene fluoride microfiltration membranes by silver-based metal-organic frameworks (AgMOFs). Polydopamine (PDA) coating was also used to carry out this surface modification. In this study, AgMOFs were synthesized and in-situ grafted on the membrane surface simultaneously using ultrasonication for the first time. Unlike the conventional methods in which AgMOFs are prone to be washed away, the AgMOFs synthesized by ultrasonic-assisted method strongly bonded with the PDA-coated membrane. In addition, the MOF-PDA membrane fabricated by this method showed more uniform and size-controlled AgMOFs on the membrane surface than other conventional methods with large MOF clusters. The AgMOF-functionalized membrane displayed enhanced static antibacterial activity and dynamic biofouling resistance compared to those of the PDA-coated and pristine membranes while in contact with the model bacteria, Escherichia coli and Staphylococcus aureus. These results were evidenced by a larger inhibition zone area, a decline in viable cells observed in static antibacterial experiments, and more retained water flux in dynamic biofouling experiments. Altogether, our findings indicate that the in-situ synthesis of AgMOFs on membrane surfaces was successful by this facile and environmentally friendly method which can be considered in future studies with the purpose of surface modification for diverse applications.

Electrochemical investigation for enhancing cellular antioxidant defense system based on a superoxide anion sensor

The dynamic balance of the redox system in living organisms can be disrupted by excessive superoxide anion (O2•−), which would lead to oxidative stress and induce a variety of diseases. In this case, the antioxidant defense system plays a vital role in maintaining life and health. Thus, constructing a highly sensitive sensor for detecting O2•− and enhancing antioxidant defense systems are of great significance for reducing the risk of diseases caused by oxidative stress. In this work, a MOF-derived carbon-based nanomaterial (AgNPs-MC) was synthesized through silver-based metal organic framework. The non-enzymatic O2•− electrochemical sensor fabricated by AgNPs-MC showed excellent catalytic ability, wide linear range, and an ultra-low detection limit (12.3 pM, S/N = 3). In addition, it could be successfully used to detect O2•− released by living cells. More importantly, the synergistic effect of superoxide dismutase (SOD) and tea polyphenols (TP) to scavenge O2•− in biological systems was first studied by electrochemical method, which provides a novel strategy for improving the antioxidant defense system of living cells. Constructed sensing platform and developed antioxidant strategy have potential value for their future application in the diagnosis and treatment of diseases related oxidative stress.

Outstanding anti-bacterial thin-film composite membrane prepared by incorporating silver-based metal–organic framework (Ag-MOF) for water treatment

Biofouling was a considerable issue in the water treatment by membrane technology. In this study, high anti-bacterial property Ag-MOF was synthesized followed by embedding into polyamide layer with vacuum-assisted interfacial polymerization process to prepare an Ag-MOF incorporated membrane. The successful preparation of Ag-MOF and membranes was verified by FT-IR, FESEM, XPS, XRD, BET, zeta potential and contact angle test. On account to the strong hydrophility, porous structure, electronegativity and antibacterial property of Ag-MOF, modified membranes showed excellent performance for dyes, salts and bacteria. The water permeability of modified membranes was increased from 9.2 to 14.3 L m-2h−1 bar−1 and the rejection rate of MO, MB and RB of the optimum membranes were 95.4%, 87.8% and 99.3%, respectively. The rejection rate of Na2SO4 and MgSO4 were increased from 54.0% and 36.6% to 84.1% and 73.1%. The sterilization rate of modified membranes to E. coli and S. aureus both exceeded 99%. The leaching test of Ag+ evaluated the potential mechanism of anti-bacterial property. Moreover, dynamic bio-fouling test were used to detect the actual status in the filtration process. Those results suggested that modified membranes showed a strong resistance to bio-foulants thus enlarged the scope of application of membranes for water treatment.

Water-Stable Silver-Based Metal-Organic Frameworks of Quaternized Carboxylates and Their Antimicrobial Activity.

Three-dimensional (3D) and two-dimensional (2D) Ag-based zwitterionic metal-organic frameworks (MOFs) [Ag2(Cedcp)]n (1, 3D, H3CedcpBr denotes N-(carboxyethyl)-(3,5-dicarboxyl)-pyridinium bromide) and {[Ag4(Cmdcp)2(H2O)4]·4H2O}n (2, 2D, H3CmdcpBr denotes N-(carboxymethyl)-(3,5-dicarboxyl)-pyridinium bromide) have been prepared and investigated for antimicrobial activity via minimal inhibition concentration (MIC) test and killing kinetic assay. Both MOFs 1 and 2 show good water stability and solubility ascribed to their characteristic aromatic rings and positively charged pyridinium of the ligands, as well as the presence of Ag+ on their surface, leading to strong antimicrobial activity and a wide antimicrobial spectrum toward Gram-negative and positive bacteria. The results indicated that MOF 2 possesses a faster antibacterial activity (60 min) than MOF 1 (120 min). Scanning electron microscopy analysis further suggests that the Ag-based MOFs are capable of rupturing the bacterial membrane, leading to cell death. Moreover, both MOFs exhibit little hemolytic activity against mouse erythrocytes and show good biocompatibility in vitro, rendering MOFs 1 and 2 potential therapeutic agents for diseases caused by bacteria.