Metal–Organic Framework (MOF) Hybrid as a Tandem Catalyst for Enhanced Therapy against Hypoxic Tumor Cells

Encapsulation of active biomolecules and/or nanoparticles in metal–organic frameworks (MOFs) remains a great challenge in biomedical applications. In this work, through a stepwise in situ growth method, a black phosphorus quantum dot (BQ) and catalase were precisely encapsulated into the inner and outer layers of MOFs, respectively. The integrated MOF system as a tandem catalyst could convert H₂O₂ into O₂ in MOF‐stabilized catalase outer layer, and then O₂ was directly injected into MOF‐sensitized BQ inner, leading to high quantum yield of singlet oxygen. Upon internalization, the photodynamic therapy efficiency of the MOF system was 8.7‐fold greater than that without catalase, showing an enhanced therapeutic effect against hypoxic tumor cells. Furthermore, by coupling with photothermal therapy of BQs, photodynamic‐thermal synergistic therapy was realized both in vitro and in vivo.     

DNAzyme‐Loaded Metal–Organic Frameworks (MOFs) for Self‐Sufficient Gene Therapy

DNAzymes have been recognized as potent therapeutic agents for gene therapy, while their inefficient intracellular delivery and insufficient cofactor supply precludes their practical biological applications. Metal–organic frameworks (MOFs) have emerged as promising drug carriers without in‐depth consideration of their disassembled ingredients. Herein, we report a self‐sufficient MOF‐based chlorin e6‐modified DNAzyme (Ce6‐DNAzyme) therapeutic nanosystem for combined gene therapy and photodynamic therapy (PDT). The ZIF‐8 nanoparticles (NPs) could efficiently deliver the therapeutic DNAzyme without degradation into cancer cells. The pH‐responsive ZIF‐8 NPs disassemble with the concomitant release of the guest DNAzyme payloads and the host Zn²⁺ ions that serve, respectively, as messenger RNA‐targeting agent and required DNAzyme cofactors for activating gene therapy. The auxiliary photosensitizer Ce6 could produce reactive oxygen species (ROS) and provide a fluorescence signal for the imaging‐guided gene therapy/PDT.     

Significant Enhancement of C2H2/C2H4 Separation by a Photochromic Diarylethene Unit: A Temperature‐ and Light‐Responsive Separation Switch

A dual temperature‐ and light‐responsive C₂H₂/C₂H₄ separation switch in a diarylethene metal–organic framework (MOF) is presented. At 195 K and 100 kPa this MOF shows ultrahigh C₂H₂/C₂H₄ selectivity of 47.1, which is almost 21.4 times larger than the corresponding value of 2.2 at 293 K and 100 kPa, or 15.7 times larger than the value of 3.0 for the material under UV at 195 K and 100 kPa. The origin of this unique control in C₂H₂/C₂H₄ selectivity, as unveiled by density functional calculations, is due to a guest discriminatory gate‐opening effect from the diarylethene unit.     

An Ultra‐Robust and Crystalline Redeemable Hydrogen‐Bonded Organic Framework for Synergistic Chemo‐Photodynamic Therapy

The low structural stability of hydrogen‐bonded organic frameworks (HOFs) is a thorny issue retarding the development of HOFs. A rational design approach is now proposed for construction of a stable HOF. The resultant HOF (PFC‐1) exhibits high surface area of 2122 m² g⁻¹ and excellent chemical stability (intact in concentrated HCl for at least 117 days). A new method of acid‐assisted crystalline redemption is used to readily cure the thermal damage to PFC‐1. With periodic integration of photoactive pyrene in the robust framework, PFC‐1 can efficiently encapsulate Doxorubicin (Doxo) for synergistic chemo‐photodynamic therapy, showing comparable therapeutic efficacy with the commercial Doxo yet considerably lower cytotoxicity. This work demonstrates the notorious stability issue of HOFs can be properly addressed through rational design, paving a way to develop robust HOFs and offering promising application perspectives.     

Controllable Modular Growth of Hierarchical MOF‐on‐MOF Architectures

Fabrication of hybrid MOF‐on‐MOF heteroarchitectures can create novel and multifunctional platforms to achieve desired properties. However, only MOFs with similar crystallographic parameters can be hybridized by the classical epitaxial growth method (EGM), which largely suppressed its applications. A general strategy, called internal extended growth method (IEGM), is demonstrated for the feasible assembly of MOFs with distinct crystallographic parameters in an MOF matrix. Various MOFs with diverse functions could be introduced in a modular MOF matrix to form 3D core–satellite pluralistic hybrid system. The number of different MOF crystals interspersed could be varied on demand. More importantly, the different MOF crystals distributed in individual domains could be used to further incorporate functional units or enhance target functions.     

A Metal–Organic Framework Thin Film for Selective Mg2+ Transport

The incompatibility between the anode and the cathode chemistry limits the used of Mg as an anode. This issue may be addressed by separating the anolyte and the catholyte with a membrane that only allows for Mg²⁺ transport. Mg‐MOF‐74 thin films were used as the separator for this purpose. It was shown to meet the needs of low‐resistance, selective Mg²⁺ transport. The uniform MOF thin films supported on Au substrate with thicknesses down to ca. 202 nm showed an intrinsic resistance as low as 6.4 Ω cm², with the normalized room‐temperature ionic conductivity of ca. 3.17×10^?6 S cm^?1. When synthesized directly onto a porous anodized aluminum oxide (AAO) support, the resulting films were used as a standalone membrane to permit stable, low‐overpotential Mg striping and plating for over 100 cycles at a current density of 0.05 mA cm^?2. The film was effective in blocking solvent molecules and counterions from crossing over for extended period of time.     

Heteroepitaxial Growth of Multiblock Ln‐MOF Microrods for Photonic Barcodes

Micro/nanoscale multicolor barcodes with unique identifiability and a small footprint play significant roles in applications such as multiplexed labeling and tracking systems. Now, a strategy is reported to design multicolor photonic barcodes based on 1D Ln‐MOF multiblock heterostructures, where the domain‐controlled emissive colors and different block lengths constitute the fingerprint of a corresponding heterostructure. The excellent heteroepitaxial growth characteristics of MOFs enable the effective modulation of the coding structures, thereby remarkably increasing the encoding capacity. The as‐prepared multicolor barcodes enable an efficient authentication and exhibit great potential in fulfilling the functions of anti‐counterfeiting, information security, and so on. The results will pave an avenue to novel hybrid MOFs for optical data recording and security labels.     

Mass Spectrometric Study of Acoustically Levitated Droplets Illuminates Molecular‐Level Mechanism of Photodynamic Therapy for Cancer involving Lipid Oxidation

Even though the general mechanism of photodynamic cancer therapy is known, the details and consequences of the reactions between the photosensitizer‐generated singlet oxygen and substrate molecules remain elusive at the molecular level. Using temoporfin as the photosensitizer, here we combine field‐induced droplet ionization mass spectrometry and acoustic levitation techniques to study the “wall‐less” oxidation reactions of 18:1 cardiolipin and 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phospho‐(1′‐rac‐glycerol) (POPG) mediated by singlet oxygen at the air–water interface of levitated water droplets. For both cardiolipin and POPG, every unsaturated oleyl chain is oxidized to an allyl hydroperoxide, which surprisingly is immune to further oxidation. This is attributed to the increased hydrophilicity of the oxidized chain, which attracts it toward the water phase, thereby increasing membrane permeability and eventually triggering cell death.     

Programmed Release of Dihydroartemisinin for Synergistic Cancer Therapy Using a CaCO3 Mineralized Metal–Organic Framework

Dihydroartemisinin (DHA) has attracted increasing attention as an anticancer agent. However, using DHA to treat cancer usually depends on the synergistic effects of exogenous components, and the loss of DHA during delivery reduces its effectiveness in cancer therapy. Reported herein is a programmed release nanoplatform of DHA to synergistically treat cancer with a Fe‐TCPP [(4,4,4,4‐(porphine‐5,10,15,20‐tetrayl) tetrakis(benzoic acid)] NMOF (nanoscale MOF) having a CaCO₃ mineralized coating, which prevents DHA leakage during transport in the bloodstream. When the nanoplatform arrives at the tumor site, the weakly acidic microenvironment and high concentration of glutathione (GSH) trigger DHA release and TCPP activation, enabling the synergistic Fe²⁺‐DHA‐mediated chemodynamic therapy, Ca²⁺‐DHA‐mediated oncosis therapy, and TCPP‐mediated photodynamic therapy. In vivo experiments demonstrated that the nanoplatform showed enhanced anticancer efficiency and negligible toxicity.     

Enhanced Drug Delivery by Dissolution of Amorphous Drug Encapsulated in a Water Unstable Metal–Organic Framework (MOF)

Encapsulating a drug molecule into a water‐reactive metal–organic framework (MOF) leads to amorphous drug confined within the nanoscale pores. Rapid release of drug occurs upon hydrolytic decomposition of MOF in dissolution media. Application to improve dissolution and solubility for the hydrophobic small drug molecules curcumin, sulindac, and triamterene is demonstrated. The drug@MOF composites exhibit significantly enhanced dissolution and achieves high supersaturation in simulated gastric and/or phosphate buffer saline media. This combination strategy where MOF inhibits crystallization of the amorphous phase and then releases drug upon MOF irreversible structural collapse represents a novel and generalizable approach for drug delivery of poorly soluble compounds while overcoming the traditional weakness of amorphous drug delivery: physical instability of the amorphous form.     

A Tale of Two Trimers from Two Different Worlds: A COF‐Inspired Synthetic Strategy for Pore‐Space Partitioning of MOFs

The introduction of a symmetry‐ and size‐matching pore‐partitioning agent in the form of either a molecular ligand, such as 2,4,6‐tri(4‐pyridinyl)‐1,3,5‐triazine ( tpt ), or a metal‐complex cluster, into the hexagonal channels of MIL‐88/MOF‐235‐type (the acs net) to create pacs ‐type (partitioned acs ) crystalline porous materials is an effective strategy to develop high‐performance gas adsorbents. We have developed an integrated COF–MOF coassembly strategy as a new method for pore‐space partitioning through the coassembly of [(M₃(OH)_1?x(O)_x(COO)₆] MOF‐type and [B₃O₃(py)₃] COF‐type trimers. With this strategy, the coordination‐driven assembly of the acs framework occurred concurrently and synergistically with the COF‐1‐type condensation of pyridine‐4‐boronic acid into a C₃‐symmetric trimeric boroxine molecule. The resulting boroxine‐based pacs materials exhibited dramatically enhanced gas‐sorption properties as compared to nonpartitioned acs ‐type materials and are among the most efficient NH₃‐sorption materials.     

A Noble‐Metal‐Free Metal–Organic Framework (MOF) Catalyst for the Highly Efficient Conversion of CO2 with Propargylic Alcohols

Cyclization of propargylic alcohols with CO₂ is an important reaction in industry, and noble‐metal catalysts are often employed to ensure the high product yields under environmentally friendly conditions. Herein a porous noble‐metal‐free framework 1 with large 1D channels of 1.66 nm diameter was synthesized for this reaction. Compound 1 exhibits excellent acid/base stability, and is even stable in corrosive triethylamine for one month. Catalytic studies indicate that 1 is an effective catalyst for the cyclization of propargylic alcohols and CO₂ without any solvents under mild conditions, and the turnover number (TON) can reach to a record value of 14 400. Furthermore, this MOF catalyst also has rarely seen catalytic activity when the biological macromolecule ethisterone was used as a substrate. Mechanistic studies reveal that the synergistic catalytic effect between Cu^I and In^III plays a key role in the conversion of CO₂.     

A Membrane‐Intercalating Conjugated Oligoelectrolyte with High‐Efficiency Photodynamic Antimicrobial Activity

A membrane‐intercalating conjugated oligoelectrolyte (COE), PTTP , was designed and synthesized with the goal of providing red‐shifted absorption spectra relative to previously synthesized COE analogs. Specifically, electron‐rich and electron‐poor subunits were introduced in the conjugated backbone to modulate the band gap. PTTP exhibits maxima of absorption at 507 nm and of emission at 725 nm. PTTP can also efficiently function to generate singlet oxygen in situ (Φ_Δ≈20 %) and has appropriate topology and dimensions to interact with lipid membranes. The resulting rapid membrane insertion and sensitizing ability provide PTTP with a highly efficient antibacterial capability under a low light dose (0.6 J cm⁻²) toward Gram‐negative bacteria E. coli, making it a remarkably efficient optically mediated antimicrobial agent.     

Nucleus‐Targeted Organoiridium–Albumin Conjugate for Photodynamic Cancer Therapy

An organoiridium–albumin bioconjugate ( Ir1‐HSA ) was synthesized by reaction of a pendant maleimide ligand with human serum albumin. The phosphorescence of Ir1‐HSA was enhanced significantly compared to parent complex Ir1 . The long phosphorescence lifetime and high ¹O₂ quantum yield of Ir1‐HSA are highly favorable properties for photodynamic therapy. Ir1‐HSA mainly accumulated in the nucleus of living cancer cells and showed remarkable photocytotoxicity against a range of cancer cell lines and tumor spheroids (light IC₅₀; 0.8–5 μm , photo‐cytotoxicity index PI=40–60), while remaining non‐toxic to normal cells and normal cell spheroids, even after photo‐irradiation. This nucleus‐targeting organoiridium‐albumin is a strong candidate photosensitizer for anticancer photodynamic therapy.     

Long‐Term Photostability in Terephthalate Metal–Organic Frameworks

Prolonged (weeks) UV/Vis irradiation under Ar of UiO‐66(Zr), UiO66 Zr‐NO₂, MIL101 Fe, MIL125 Ti‐NH₂, MIL101 Cr and MIL101 Cr(Pt) shows that these MOFs undergo photodecarboxylation of benzenedicarboxylate (BDC) linker in a significant percentage depending on the structure and composition of the material. Routine characterization techniques such as XRD, UV/Vis spectroscopy and TGA fail to detect changes in the material, although porosity and surface area change upon irradiation of powders. In contrast to BCD‐containing MOFs, zeolitic imidazolate ZIF‐8 does not evolve CO₂ or any other gas upon irradiation.     

Decorated Traditional Zeolites with Subunits of Metal–Organic Frameworks for CH4/N2 Separation

Metal–organic frameworks (MOF) materials are promising materials for gas separation, but their application still faces various challenges. A strategy is now reported for introducing subunits of MOFs into traditional zeolite frameworks to obtain applicable adsorbents with advantages of both zeolites and MOFs. The subunits of ZIFs were introduced into zeolite Y and zeolite ZSM‐5 for CH₄/N₂ separation. Both the molecular simulation and experimental results validated that the IAST CH₄/N₂ selectivity of the resulting samples greatly improved (above 8, at 100 kPa and 25 °C) with the incorporation of ZIF subunits into zeolites structure, and the selectivities were obviously higher than that of zeolites and even better than that of ZIFs. This strategy not only gave rise to an efficient adsorbent for CH₄/N₂ separation but also provided ideas for design of other adsorption and separation materials.     

Ultrathin Metal–Organic Framework Nanosheets with Ultrahigh Loading of Single Pt Atoms for Efficient Visible‐Light‐Driven Photocatalytic H2 Evolution

A surfactant‐stabilized coordination strategy is used to make two‐dimensional (2D) single‐atom catalysts (SACs) with an ultrahigh Pt loading of 12.0 wt %, by assembly of pre‐formed single Pt atom coordinated porphyrin precursors into free‐standing metal–organic framework (MOF) nanosheets with an ultrathin thickness of 2.4±0.9 nm. This is the first example of 2D MOF‐based SACs. Remarkably, the 2D SACs exhibit a record‐high photocatalytic H₂ evolution rate of 11 320 μmol g^?1 h^?1 via water splitting under visible light irradiation (λ>420 nm) compared with those of reported MOF‐based photocatalysts. Moreover, the MOF nanosheets can be readily drop‐casted onto solid substrates, forming thin films while still retaining their photocatalytic activity, which is highly desirable for practical solar H₂ production.