Fe-based Metal-organic Frameworks Research Articles

High-Density Atomic Level Defect Engineering of 2D Fe-Based Metal-Organic Frameworks Boosts Oxygen and Hydrogen Evolution Reactions.

Electrocatalysts based on metal-organic frameworks (MOFs) attracted significant attention for water splitting, while the transition between MOFs and metal oxyhydroxide poses a great challenge in identifying authentic active sites and long-term stability. Herein, we employ on-purpose defect engineering to create high-density atomic level defects on two-dimensional Fe-MOFs. The coordination number of Fe changes from 6 to 4.46, and over 28% of unsaturated Fe sites are formed in the optimized Fe-MOF. In situ characterizations of the most optimized Fe-MOF0.3 electrocatalyst during the oxygen evolution reaction (OER) process using Fourier transform infrared and Raman spectroscopy have revealed that some Fe unsaturated sites become oxidized with a concomitant dissociation of water molecules, causing generation of the crucial *OH intermediates and Fe oxyhydroxide. Moreover, the presence of Fe oxyhydroxide is compatible with the Volmer and Heyrovsky steps during the hydrogen evolution reaction (HER) process, which lower its energy barrier and accelerate the kinetics. As a result, the optimized Fe-MOF electrodes delivered remarkable OER (259 mV at 10 mA cm-2) and HER (36 mV at 10 mA cm-2) performance. Our study offers comprehensive understanding of the effect of phase transformation on the electrocatalytic process of MOF-based materials.

Structural optimization, characterization, and evaluation ofbinding mechanism of aptamers against bovine pregnancy-associated glycoproteins and their application in establishment of a colorimetric aptasensor using Fe-based metal-organic framework as peroxidase mimic tags.

Atruncated aptamer (designated A24-3) was identifiedthat specifically binds to bovine pregnancy-associated glycoproteins (bPAG9) with a low dissociation constant (2.04nM) through two truncation approaches. Circular dichroism spectroscopy indicated that A24-3 formed parallel G-quadruplexes, which was subsequently confirmed using nuclear magnetic resonance (NMR) spectroscopy. Furthermore, a molecular dynamics simulation was employed to investigate the recognition mechanism of A24-3 and bPAG9. Interaction analysis showed that A24-3 folded into a parallel G-quadruplex structure with three G-tetrads, primarily through numerous hydrogen bonds and hydrophobic and π-π interactions. Finally, a novel colorimetric aptasensor was developed for detecting bPAG9 using A24-3 and an Fe-based metal-organic framework as target recognition elements and enzyme mimics, respectively. The method demonstrated a broad detection range from 0.5 to 50ng/mL, with a low detection limit of 0.03ng mL-1, and exhibited a good recovery (91.0-102%) for bPAG9-spiked serum samples. Additionally, the aptasensor was successfully applied todetecting the pregnancy-specific biomarker bPAGs in serum samples.

Reimagining Anti-Inflammatory Drugs Delivery: The Integration of Ordered Mesoporous Silica and MOF Materials for Enhanced Therapeutic Outcomes

Abstract Migraine, one of the neurological conditions, affects approximately 15% of the global population. It is characterized by intense headaches accompanied by nausea, vomiting, and heightened sensitivity to light. The first line of drugs for treating migraine are non-steroidal anti-inflammatory drugs. Unfortunately, these medications suffer from poor solubility in water, uncontrolled release, and numerous adverse side effects. In order to maximize their therapeutic effect by preventing premature release and degradation, novel drug delivery systems based on composites are being dynamically developed. Herein, the biocompatible ketoprofen, naproxen sodium, and diclofenac sodium vehicles integrating ordered mesoporous silica (SBA-16) with Fe-based metal–organic frameworks (MIL-101(Fe)) were synthesized via the solvothermal method. The composites were characterized by different percentages of MIL-101(Fe) 
(25 and 50 wt.%), which had a significant impact on their porosity, structure, and number of functional groups. The SBA-16@MIL-101(Fe)-25 and SBA-16@MIL-101(Fe)-50 samples exhibited BET surface areas of 768 and 324 m2/g, respectively. Their sorption capacities towards selected anti-inflammatory drugs were in the range of 141-318 mg/g for ketoprofen, 481-490 mg/g for naproxen sodium, and 246-589 mg/g for diclofenac sodium, notably exceeding the values obtained for pure mesoporous silica (5-9 mg/g). Morphological defects and specific functional groups, derived from SBA-16 and MIL-101(Fe), contributed to generating new adsorption sites in composites, enhancing host-guest interactions. The drug release profiles were determined by the carrier porosity, surface charge, and the presence of functional groups. The diffusion of ketoprofen and diclofenac sodium from the composites into the phosphate buffer (pH 7.7), mimicking rectal fluid, occurred in a more controlled manner compared to pristine silica. The SBA-16@MIL-101(Fe)-50 carrier released 82% of ketoprofen and 90% of diclofenac sodium over 24 hours.

Tetracycline removal via photo-Fenton processes using Fe-based metal-organic frameworks loaded with Bi2S3: Performance evaluation and insights into the charge-transfer mechanism

Combining photocatalytic technology with the Fenton system may help overcome these technologies’ limitations. Photo-Fenton catalysis is economical and eco-friendly. The Fe based heterogeneous photo-Fenton process appears to be a promising wastewater treatment technology. Herein, an Fe based metal–organic framework (MIL-101 (Fe)) was produced via hydrothermal processing. Subsequently, Bi2S3 was loaded onto the surface of MIL-101 (Fe) to form a composite catalyst. A type-II heterojunction was established between MIL-101 (Fe) and Bi2S3. The 10 % Bi2S3-loaded MIL-101 (Fe) (MBS-10) was effective in the photocatalytic degradation of tetracycline, particularly after H2O2 addition. This outcome was due to the enhanced generation of radical species through the photo-Fenton process. The MBS-10 photocatalyst promoted Fe (II)/Fe (III) cycling in the presence of H2O2 and under visible light irradiation. MBS-10 also showed a higher kinetic rate constant during the photocatalytic reaction compared to MIL-101 (Fe) and Bi2S3, suggesting enhanced activity through greater electron-hole separation. Furthermore, MBS-10 proved to be stable and reusable photocatalyst after four testing cycles. The charge-transfer mechanism was elucidated through radical scavenging experiments which demonstrated that superoxide and hydroxyl radicals are the major charge carriers. Therefore, the Bi2S3-MIL-101 (Fe) composite exhibits great potential for degrading tetracycline antibiotics.

Novel dopamine-derived carbon modified fe-based metal–organic framework enhanced aptasensor rendering ultrasensitive electrochemical detection of oxytetracycline

In the present work, an aptasensor with dual binding sites based on Au NPs modified with self-polymerized polydopamine (PDA) and Fe-MOF is successfully constructed. In terms of standard electron transfer, the cyclic voltammetry (CV) analysis showcases a rate constant (ks) of 96.0 s−1, signifying an exceptional electron transfer rate of oxytetracycline at the sensor interface of Apt/Au@PDA@NH2-MIL-101(Fe)/GCE. Further deepening the investigation into electrochemical kinetics using chronoamperometry (CA), we investigated the electrocatalytic parameters (Kcat) of Au@PDA@NH2-MIL-101(Fe) in relation to oxytetracycline. The results divulged an impressive average Kcat value of 3.06 × 105 M−1 S-1. This evidence robustly suggests the superior electrocatalytic activity of Au@PDA@NH2-MIL-101(Fe) when it comes to oxytetracycline oxidation. A custom-designed portable rapid detection platform was developed, achieving detection limits of 6.88 nM under static water flow conditions and 5.56 nM under dynamic conditions. Remarkably, the self-polymerization of PDA on Au NPs not only refines their size but also boosts their interaction with biomolecules, thereby promising excellent biocompatibility. Moreover, the abundance of –COOH groups and unsaturated Fe3+ sites on the NH2-MIL-101(Fe) surface furnishes a considerable number of grafting sites for the aptamer. More importantly, the redox interplay between Au@PDA and NH2-MIL-101(Fe) accelerates electron movement, thus amplifying the electrochemical signal and the detection sensitivity for oxytetracycline.

Enhancing the Fenton catalytic activity of Fe-MOFs by incorporation of carbon nanotubes: The crucial role of C-O-Fe coordination structure

Fe-based metal–organic frameworks (MOFs) have garnered significant attention as catalysts for heterogeneous Fenton reactions, while the limited efficiency of the Fe(III)/Fe(II) redox cycle hinders their widespread use in wastewater treatment. Herein, we successfully incorporated carbon nanotubes (CNTs) into MIL-101(Fe) to modulate the coordination environment of Fe for achieving better catalytic activity. The MIL-101(Fe)/CNTs/H2O2 system shows outstanding performance in degrading various pollutants, with the catalytic activity of the MIL-101(Fe)/CNTs composites (98.8%) significantly surpassing that of MIL-101(Fe) alone (26.4%) or CNTs alone (3.5%). Multiple experimental findings suggest that this synergistic effect is primarily attributed to the C-O-Fe bridge bonds resulting from the interaction of surface carboxyl groups on CNTs with Fe in MIL-101(Fe). This unique coordination structure accelerates the redox cycle of Fe(III)/Fe(II), thereby promoting the generation of hydroxyl radicals (HO•). Furthermore, the MIL-101(Fe)/CNTs composites demonstrate excellent reusability and stability, maintaining effectiveness over a wide pH range from 3.0 to 6.5. This study provides new insights into regulating the microstructure of Fe-based MOFs to enhance their Fenton catalytic activity.

Fluorescent/colorimetric probe for the detection of Cr(Ⅵ) based on MIL-101(Fe)–NH2 with peroxidase-like activity

In the present research, Fe-based metal-organic frameworks (MIL-101(Fe)–NH2) nanoparticles were synthesized by simple solvothermal methods and used to assay Cr(Ⅵ). The MIL-101(Fe)–NH2 performs dual functions: the 2-aminoterephthalic acid (NH2-BDC) ligand endows a strong fluorescence emission, and the Fe metal nodes are able to facilitate the oxidation of 3,3′,5,5′- tetramethylbenzidine (TMB) directly, resulting in the generation of oxidized-TMB (ox-TMB). Our research results showed that reducing agents such as ascorbic acid (AA) can collapse the structures of MIL-101(Fe)–NH2 because of the reduction of Fe3+ by AA, resulting in release of NH2-BDC. In the presence of Cr(Ⅵ), the fluorescence intensity of the MIL-101(Fe)–NH2 + AA system will be decreased due to the competitive reduction of Fe3+ and Cr(Ⅵ). Nevertheless, Cr(Ⅵ) can significantly accelerate the oxidation of TMB by MIL-101(Fe)–NH2 as it boosts the electron transfer rate between Fe3+ and Fe2+. Therefore, a fluorescent/colorimetric dual-mode platform was developed for the detection of Cr(Ⅵ) with an extensive linear range (7.5–750 μg/L and 13.3–1000 μg/L) as well as a remarkably low detection limit (0.99 μg/L and 1.98 μg/L). This MOF with the ability to release ligands not only provides inspiration for the design of new luminescent materials, but also offers a novel and reliable solution for the detection of Cr(Ⅵ).

Green electrospun Fe-based MOFs incorporated polyvinyl alcohol/carboxymethyl chitosan nanofibrous membranes for enhanced adsorption of tetracycline hydrochloride

Tetracycline hydrochloride (TCH) removal from wastewater has drawn much attention recently, although it still remains challenging. Herein, Fe-based metal-organic frameworks (MOFs) incorporated nanofibrous membranes were prepared by green electrospinning and applied as adsorbents to remove TCH. The presence of MOFs noticeably improved specific surface area of the nanofibrous membranes, and adsorption capability increased with the amount of MOFs within membranes. As the temperature increased, the amount of TCH that was adsorbed continuously reduced, and the maximum adsorption capacity (248.5 mg/g) was attained at 273 K. The adsorption behavior of the nanofibrous membranes followed Langmuir isotherm model and pseudo-second-order kinetic model. Thermodynamic parameters suggested that the adsorption process was spontaneous and exothermic. A series of interactions between the membrane and TCH, such as pore filling, coordination bonding, π-π interaction, hydrogen bonding interaction and electrostatic interaction, combined to enhance the adsorption performance. Good stability and adsorption capability were demonstrated by the nanofibrous membranes, suggesting that they could be used for effective and affordable water purification.

Exploring Biliverdin's Molecular Interactions with Cu- and Fe-Based MOFs: A Unified In Vitro Study with Photoacoustic Analysis.

Metal-organic frameworks (MOFs) have shown promise in enhancing the stability of biomolecules. Herein, biliverdin (BVD), a photoacoustic (PA) and fluorescent agent, was immobilized within the pores of NH2-MIL-101 (Fe) (FeMOFs) and on the surface of CuBTC crystallites (CuMOFs). MOFs were found to enhance the fluorescence emission and quench the PA intensity of biliverdin. Fluorescence and PA studies, in tandem with DFT simulations, demonstrated that the spectral interactions between MOFs and BVD resulted from interactions between biliverdin and the MOF pores and surfaces in addition to alterations in the HOMO-LUMO energy gap. The MOF internal structure of the MOF played a role in BVD loading, with the FeMOFs enabling greater BVD encapsulation, while CuMOF interactions with BVD primarily took place on the MOF surface. The role of these surface vs pore interactions in the release of biliverdin was explored. This study demonstrates that the effects of the MOF internal structure, surface interactions, and energy interactions should be taken into consideration for biomolecule loading in MOFs.

Boosted photo-Fenton-like process for selective degradation of emerging contaminants by dehydrated Fe-based metal–organic framework with thermodynamically-favorable center metal electron density and confinement effect

The Heterogeneous Fenton reaction has long stood out as a highly effective technology for water purification. However, it is nowadays facing challenges such as low selectivity, sluggish Fe(III) reduction, and limited H2O2 conversion efficiency. Herein, dehydrated MIL-100(Fe)-250 was synthesized through thermal treatment, demonstrating superior efficiency in removing emerging contaminants, with a three-fold efficiency higher than undehydrated sample. The dehydrated MIL-100(Fe)-250 exhibited selective acceleration in the removal of quinolones and phenolic organics, rendering the system resistant to interference from coexisting matter. Through in-situ diffuse reflectance infrared Fourier-transform spectroscopy and density functional theory calculation, it was manifested that dehydration process regulates the steric hindrance and local electron density of Fe ions. This adjustment enhances charge transfer, thereby facilitating Fe(III) reduction and promoting the H2O2 activation and conversion efficiency. Moreover, the quasi-steady-state concentrations of hydroxyl radical in MIL-100(Fe)-250 were found to be 2.2 times higher than that those in undehydrated sample. Impressively, the dehydrated MIL-100(Fe)-250 displayed adaptability across a broad pH range of 5.0–9.0. The present study underscores the significant potential of porous MIL-100(Fe)-250 with spatial confinement, which imparts a clear size exclusion effect. As a result, this catalyst emerges as a promising candidate for eliminating contaminants in real water matrices, offering a viable strategy for water pollution control.

(Nanocarbons Division Poster Award, 3rd Place) Hybrid Supercapacitance and Stability of Fe-Based Metal-Organic Frameworks/Graphene Oxide Nanoribbons Composite Allover the pH Range

Adopting renewable energy sources is growing fast, and hence it should be accompanied by tremendous efforts to develop energy storage technologies that can mitigate the intermittent nature of these sources. Supercapacitors (SCs) are considered among the most promising technologies for that purpose due to their high durability, power density, and charging/discharging competency. SCs have two types according to their electrochemical charge storage mechanism: pseudocapacitance (PCs) or battery-like behavior and electrochemical double-layer capacitors (EDLCs). The development of next-generation supercapacitors requires a holistic approach that integrates both mechanisms. Because of their huge surface area, porous structure, and abundance of active redox sites, metal-organic frameworks (MOFs) have exceptional potential in energy storage devices. However, due to the MOFs’ low conductivity and stability, they are in need to be mixed with highly conductive and stable materials such as carbon-based ones.In this work, Fe-based MOFs were selected to be responsible for mainly the battery-like contribution to the overall supercapacitance due to the presence of the redox-active sites. Even though little attention has been given to the Fe-based MOFs they showed a promising performance in several solutions, with low stability.1,2 To enhance the Fe-MOFs stability and conductivity and add an EDLC component to the overall capacitance behavior graphene oxide nanoribbon (GONRs) was used. The GONRs' exceptional properties such as ultrathin two-dimensional structures, superior mechanical behavior, strong chemical stability, and high electrical conductivity make them promising materials for supercapacitor applications.In this study, Fe-MOFs were synthesized using a hydrothermal method,3 and GONRs were prepared using an oxidative unzipping method.4 A composite of Fe-MOFs/GONRs was prepared by physical mixing. The physical and chemical properties of the synthesized Fe-MOFs, GONRs, and Fe-MOFs/GONRs were characterized using XRD, SEM, TEM, FT-IR, Raman spectroscopy, and XPS. Since the electrolyte properties have a substantial impact on the supercapacitive behavior and stability of the electrode materials, the specific capacitance of the prepared composites was measured in 1M H2SO4, 1M KOH, 1M K2SO4, and 1M KCl utilizing different evaluation systems (three and two-electrode systems). The Fe-MOFs/GONRs composite showed a significant synergistic effect in comparison to its pure components. Further discussion will be given regarding the pH and ion size/type effect on the supercapacitive performance and stability.

Vanadium as a Ti-like mediator boosting electronic transmission in Fe-based MOFs for photocatalytic sterilization

Efficient metal–organic frameworks (MOFs) photocatalytic bactericidal catalysts are urgently needed in water purification. Herein, a Fe-MOF (MIL-88B-NH2(V1Fe5) with promoted electron transport was achieved by vanadium (V) ions doping and V/Fe ratio optimization, showing excellent photocatalytic bactericidal activity against E. coli under visible light irradiation (99.92%). The efficient antibacterial mechanism, V as a Ti-like mediator boosting electronic transmission in MIL-88B-NH2(V1Fe5), was revealed by its band structure, transient photocurrent, electrochemical impedance spectroscopy, and scavenger quenching experiments. The enhancement of photocatalytic bactericidal performance of Fe-MOFs by V–ion-doping was confirmed by two other Fe-MOFs, MIL-53-NH2(V1Fe5) and MIL-101-NH2(V1Fe5), with the same metal ions and ligands, both of which have higher performance than the corresponding undoped MOFs. Among them, MIL-88B-NH2(V1Fe5) exhibits the highest photocatalytic bactericidal activity due to its suitable metal clusters ([M(μ 3-O)] cluster) and topological structure (three-dimensional rhomboid network structure). This work demonstrated the amplification effect of V ion doping on electron transport in Fe-MOFs photocatalysts.

Nano-photosensitizers with gallic acid-involved Fe–O–Cu “electronic storage station” bridging ligand-to-metal charge transfer for efficient catalytic theranostics

NH2-MIL-88B (Fe) (MOF) is a promising photocatalytic material for antitumor therapy because of its distinctive electronic structure. However, inadequate separation of photo-generated electrons and slow reaction rate in low/high-valence iron (Fe) cycles limit their clinical application. In the present study, “electronic storage station” as a ligand-to-metal charge transfer bridge bond was constructed to inhibit recombination of electron/hole under 650 nm laser irradiation. Cupric (Cu) ions and gallic acid (GA) were self-assembled into a MOF (denoted as CGMOF) to create an FeO(GA)Cu bridge bond. GA, characterized by robust electron delocalization and abundant electron-donating groups, significantly enhances electron transfer efficiency for photodynamic therapy (PDT). CGMOF can respond to endogenous glutathione and release cuprous ions, accelerating the iron ion/ferrous ion cycles for chemodynamic therapy (CDT). The released Fe species can serve as T2-weighted magnetic resonance imaging contrast. Extended X-ray absorption fine structure spectra confirmed the presence of GA-containing FeOCu bonds in CGMOF. Furthermore, a series of photo-electrochemical tests confirmed that the formation of FeO(GA)Cu bond prominently elevated the redox capacity and increased the carrier density of CGMOF by 2.74-fold compared to that of MOF. In addition, cinnamaldehyde was grafted onto CGMOF for tumor-responsive hydrogen peroxide self-supply. Concurrently, hyaluronic acid was surface-modified to achieve the targeted delivery of nano-photosensitizers. In summary, this study presents an innovative approach for engineering Fe-based metal–organic frameworks for synergetic PDT/CDT applications.

Multimodal Affinity-Modulated Efficient Separation of Lysozyme with a Hierarchical MXene@MOF Hybrid Framework.

The development of abiotic protein affinity adsorbents remains challenging for the accurate acquisition and analysis of specific protein species. Inspired by bacterial cell walls, a hierarchical hybrid framework is fabricated through the oriented growth of an Fe-based metal organic framework (MOF) on V2C MXene for the efficient separation of lysozyme (Lys). After directed evolution of adsorptive materials, the MXene@MOF composite rich in hydroxyl groups (termed as MX@MOF-DH) is found exerting exceptional affinity for Lys. Benefiting from hydrogen-bonding, coordination, and electrostatic interaction-mediated multimodal and multivalent affinity, MX@MOF-DH reveals rapid adsorption rate (5 min), superb enrichment factor (83.1), and favorable binding capacity (609.7 mg g-1), which outperforms other latest adsorbents. Moreover, femtomolar sensitivity is achieved even in the presence of high-abundant interfering proteins, as confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometer analysis. This work not only provides an efficient approach for selective enrichment of lysozyme but also paves an avenue to construct the protein affinity reagents for specific biological medicine and analysis applications.

Mixed-valent Fe-MOF accelerated Fe(III)/Fe(II) cycle for highly efficient photo-Fenton-like catalytic degradation of organic pollutants: Boosting mechanism and degradation pathways

Fe-based metal-organic frameworks (Fe-MOFs) show great potential as effective Fenton catalysts in practical pollutants degradation. However, the sluggish cycling rate of the Fe(III)/Fe(II) pair severely impedes their catalytic performance, and thus hinders the framework's effectiveness. In this work, by employing a mixed-valent Fe-MOF, we proposed an innovative strategy to address the limitation of Fe(III)/Fe(II) cycle of Fe-MOF in photo-Fenton-like reaction. We pioneered a direct Fe(II) proportional substitution method to synthesize a variety of mixed-valent Fe-MOFs by adjusting the FeIII/FeII ratio in the precursor, utilizing MIL-53(Fe)-NH2 as the template material. Notably, with superior accelerated Fe(III)/Fe(II) cycle, the constructed Fe-MOF-2 with a distinctive FeIII/FeII ratio of 3:1 displayed exceptional oxytetracycline (OTC) catalytic degradation capabilities, with an impressive degradation rate of 92.6 % within 30 min. The FeIII/FeII mixed-valent structure was proven to expedite the rate-determining step of PMS activation, which involved the reduction process of the Fe(III)/Fe(II) cycle. The production of more iron-unsaturated sites effectively promoted the production of SO4•− and •OH, which contributed significantly to the OTC degradation. Additionally, the possible removal intermediates, mechanism and pathways of OTC degradation in the Fe-MOF-2-based system were elucidated. This study provides a pioneering perspective, and demonstrates the potential application of mixed-valent Fe-MOF as a photo-Fenton-like catalyst.

A ratiometric fluorescence sensor for detection of organophosphorus pesticides based on enzyme-regulated multifunctional Fe-based metal-organic framework

The residues of organophosphorus pesticides (OPs) are increasing environmental pollution and public health concerns. Thus, the development of simple, convenient and sensitive method for detection of OPs is crucial. Herein, a multifunctional Fe-based MOF with fluorescence, catalytic and adsorption, is synthesized by a simple one-pot hydrothermal method. The ratiometric fluorescence sensor for detection of OPs is constructed by using only one multifunctional sensing material. The NH2-MIL-101(Fe) is able catalyze the o-phenylenediamine (OPD) into 2,3-diaminophenazine (DAP) in the presence of H2O2. The generated DAP can significantly quench the intrinsic fluorescence of NH2-MIL-101(Fe) by the fluorescence resonance energy transfer (FRET) and internal filtration effect (IFE), while producing a new measurable fluorescence. Without immobilization or molecular imprinting, pyrophosphate ion (PPi) can inhibit the peroxidase-like activity of the NH2-MIL-101(Fe) by chelating with Fe3+/Fe2+ redox couple. Moreover, PPi can also be hydrolyzed by alkaline phosphatase (ALP), the presence of OPs inhibits the activity of ALP, resulting in the increase of extra PPi preservation and signal changes of ratiometric fluorescence, the interactions of ALP with different OPs are explored by molecular docking, the OPs (e.g., glyphosate) interact with crucial amino acid residues (Asp, Ser, Ala, Lys and Arg) are indicated. The proposed sensor exhibits excellent detection performance for OPs with the detection limit of 18.7 nM, which provides a promising strategy for detection of OPs.

CPP10-targeted photoactivatable MOF nanosystem for combined photodynamic Therapy−Chemotherapy of cancer

The annual prevalence of gastric cancer has increased in recent years. Curcumin (CUR) has shown great potential in the treatment of gastric cancer; however, its low bioavailability and poor efficacy hinder its widespread clinical application. Additionally, CUR has been found to be excellent photosensitizer in photodynamic therapy. In this study, the Fe-based metal-organic framework (MOF) Fe Tetrakis (4-carboxyphenyl) porphyrin (Fe-TCPP，FT) was used as a photosensitizer and mononuclear agent. The natural anti-tumor active ingredient CUR was loaded as both a chemotherapeutic agent and photosensitizer to form the nanoparticles CUR@FT (CF). Finally, a cell-penetrating peptide (CPP10) was modified on the surface of the nanoparticles to construct a drug delivery system (named CPP10-PEG@CUR@FT, CCF) that could actively target tumor cells while exerting a synergistic therapeutic effect of chemotherapy and photodynamic therapy. This can improve the efficacy of CUR as a chemotherapeutic drug or photosensitizer, and the high drug load and pH sensitivity of FT nanoparticles provide an excellent carrier for the efficient delivery of CUR. The polyethene glycol (PEG)-conjugated CPP10 (PEG-CPP10) coating allows nanoparticles to specifically target gastric cancer cells, significantly improving the absorption of nanoparticles in vivo and in vitro and improving biosafety. We evaluated the thermal stability, drug loading capacity, and safety of FT as a drug delivery vehicle. We also assessed the in vitro photodynamic performance and toxicity of various nanoparticles and the targeting and biocompatibility of CPP10-PEG@CUR@FT. CPP10-PEG@CUR@FT could specifically target tumor cells, and its effect on killing gastric cancer cells (MKN45) under light was much stronger than that of free CUR. Its toxicity and side effects to other organs and tissues are low, offering good biosafety. The experimental results showed that FT and CUR exerted synergistic effects on photodynamic therapy and chemotherapy. In summary, our novel CUR-loaded targeted nano drug delivery system offers significant advantages by combining photodynamic therapy and chemotherapy for tumor treatment. This approach introduces a new concept for integrating chemotherapy, photodynamic therapy and targeted drug delivery, potentially providing a new strategy for the clinical treatment of gastric cancer.

Pyrazine-based iron metal organic frameworks (Fe-MOFs) with modulated O-Fe-N coordination for enhanced hydroxyl radical generation in Fenton-like process

Rational design of coordination environment of Fe-based metal-organic frameworks (Fe-MOFs) is still a challenge in achieving enhanced catalytic activity for Fenten-like advanced oxidation process. Here in, novel porous Fe-MOFs with modulated O-Fe-N coordination was developed by configurating amino terephthalic acid (H2ATA) and pyrazine-dicarboxylic acid (PzDC) (Fe-ATA/PzDC-7:3). PzDC ligands introduce pyridine-N sites to form O-Fe-N coordination with lower binding energy, which affect the local electronic environment of Fe-clusters in Fe-ATA, thus decreased its interfacial H2O2 activation barrier. O-Fe-N coordination also accelerate Fe(II)/Fe(III) cycling of Fe-clusters by triggering the reactive oxidant species mediated Fe(III) reduction. As such, Fe-ATA/PzDC-7:3/H2O2 system exhibited excellent degradation performance for typical antibiotic sulfamethoxazole (SMX), in which the steady-state concentration of hydroxyl radical (OH) was 1.6 times higher than that of unregulated Fe-ATA. Overall, this study highlights the role of O-Fe-N coordination and the electronic environment of Fe-clusters on regulating Fenton-like catalytic performance, and provides a platform for precise engineering of Fe-MOFs.

Enhanced water stability and catalytic activity of Fe-based metal–organic frameworks with co-ligands for 2,4-dichlorophenol degradation

Fe-based metal–organic frameworks (MOFs) have good photocatalytic performance, environmental friendliness, low cost, and abundance. However, their applications are limited by low water stability, particularly in the presence of light irradiation and oxidizing agents. In this study, we present a MIL-53(Fe)-based MOF using 1,4-naphthalene dicarboxylic (1,4-NDC) and 1,4-benzenedicarboxylic (H2BDC) acid co-ligands, denoted MIL-53(Fe)-Nx, where Nx represents the ratio of 1,4-NDC. This MOF exhibits high water stability and good photocatalytic activity because of the hydrophobicity of naphthalene. The removal and mineralization rates for 100 mg/L 2,4-dichlorophenol reached 100% and 22%, respectively, within 60 min. After three cycles of use, the Fe leached into the solution from the catalysts was significantly lower than the maximum permissible limit indicated in the European Union standard. Of note, 1,4-NDC can be used to make a rigid MOF, thereby improving the crystallinity, porosity, and hydrophobicity of the resultant materials. It also significantly reduced the bandgap energy and improved the charge separation efficiency of the catalysts. This study provides a route to enhance the water stability of Fe-based MOFs via a mixed-ligand strategy to expand their applications in pollutant control.

The efficiency of a granular Fe-based metal-organic framework for the persulfate oxidative degradation of levofloxacin, an emerging antibiotic in wastewater

This study presents a novel approach to solve the problems of leaching and regeneration of metal–organic frameworks (MOFs) in water treatment. The researchers developed a modified MOF by encapsulating MIL-88(Fe) with alginate. The modified MOF was then used to activate sulfate radicals with sodium persulfate for the degradation of levofloxacin (LVX) in water. Various characterization techniques, including XRD, FTIR, BET, FESEM, TG and EDS mapping, confirmed the successful synthesis of the modified MOF and revealed its characteristic facets. The catalytic and adsorptive abilities of the modified MOFs were investigated and sodium persulfate was found to be more effective than hydrogen peroxide in the degradation of LVX. Optimal degradation conditions were determined at a pH of 3, a concentration of 2.5 mM Na2S2O8 and a catalyst dosage of 0.75 g/L. The researchers also found that higher temperatures improved the removal of LVX. The granulated MOF showed remarkable stability over five cycles, although the performance gradually decreased, indicating its potential for long-term applications in water treatment. The inhibitory properties of isopropyl alcohol and ethanol suggest that sulfate radicals rather than hydroxyl radicals are involved in the degradation of LVX. In addition, the functional groups of levofloxacin, including the piperazine ring, the carboxylic acid group and the fluorine substituents, were identified as potential initiation sites for oxidation.