The two-dimensional thin metal–organic frameworks (MOF) sheet has emerged as a promising hybrid material for applications in catalysis and optoelectronic devices. However, the small size and large thickness of an MOF sheet still pose barriers toward its potential applications. Herein, a micron-sized ultrathin MOF sheet is synthesized with the assistance of benzoic acid. Benzoic acid promoted the coordination of the porphyrin center with copper ions, reduced H-stacking and J-aggregation between the layers, and induced anisotropic growth of the MOF sheet. The results reveal the growth mechanism and provide a viable method for the synthesis of ultrathin MOF sheet. The as-prepared micron-sized ultrathin MOF sheet has good dispersion and high stability, which can ensure the long-term application properties of this material. The ultrathin thickness in combination with its micron size can make MOF as useful as graphene in practical applications. The synthesis of a micron-sized ultrathin MOF sheet similar to the thickness of graphene can pave the way for effective applications of two-dimensional MOF materials.

A novel porphyrin-based two-dimensional metal–organic framework (MOF) nanodisk with small size and few layers was prepared by coordination chelation between meso-tetra(4-carboxyphenyl)porphine ligand and Zn(ii) paddlewheel metal nodes.

Here, ferric oxide-loaded metal–organic framework (FeTCPP/Fe2O3 MOF) nanorice was designed and constructed by the liquid diffusion method. The introduction of iron metal nodes and the loading of Fe2O3 can effectively catalyze the Fenton reaction to produce hydroxyl radicals (•OH) and overcome the hypoxic environment of tumor tissue by generating oxygen. The monodispersity and porosity of the porphyrin photosensitizers in the MOF structure exposed more active sites, which promoted energy exchange between porphyrin molecules and oxygen molecules for photodynamic therapy (PDT) treatment. Therefore, the generated hydroxyl radicals and singlet oxygen (1O2) can synergistically act on tumor cells to achieve the purpose of improving tumor therapy. Then the erythrocyte membrane was camouflaged to enhance blood circulation and tissue residence time in the body, and finally, the targeted molecule AS1411 aptamer was modified to achieve the high enrichment of MOF photosensitizers on a tumor domain. As a result, the MOF nanorice camouflaged by the erythrocyte membrane can effectively reduce side effects and improve the therapeutic effect of PDT and chemo-dynamic therapy (CDT). The study not only improved the efficacy of PDT and CDT in essence from the MOF nanorice but also used the camouflage method to further concentrate FeTCPP/Fe2O3 on the tumor sites, achieving the goal of multiple gains. These results will provide theoretical and practical directions for the development of tumor-targeted MOF nanomaterials.

A novel gadolinium–porphyrin metal–organic framework (MOF) nanosheet was synthesized by coordination chelation between gadolinium­(III) ions and 4,4,4,4-(porphine-5,10,15,20-tetrayl) tetrakis (benzoic acid) (TCPP). The mechanism and molecular structure of the prepared Gd-TCPP products were analyzed through the comparison of 4,4,4,4-(porphine-5,10,15,20-tetrayl) tetrakis (benzenesulfonic acid) (TPPS) and TCPP. The Gd-TCPP MOF nanosheets exhibit a high relaxation rate of 40.8 mM–1 s–1, which is better than the rates for most reported contrast agents. In addition, the photosensitive activity of the Gd-TCPP nanosheets was enhanced compared to TCPP owing to the special periodic porous structure of the MOF, indicating that the Gd-TCPP nanosheets could produce the singlet oxygen (1O2) more effectively under irradiation by visible light. Performance enhancement was observed for both metal ions and organic ligands in the Gd-TCPP MOF nanosheets. This study presents a new concept in the development bifunctional MOF nanomaterials with enhanced performance in magnetic resonance imaging and photodynamic therapy.

A three-dimensional hemin-functionalized graphene hydrogel (Hem/GH) was prepared by a facile self-assembly approach. The as-prepared Hem/GH showed good mechanical strength with a storage modulus of 609-642 kPa and a high adsorption capacity to organic dye contaminants (341 mg g for rhodamine B). Moreover, Hem/GH could be used as a photosensitizer for the photocatalytic degradation of organic dyes and displayed superior photodegradation activity of methylene blue (MB). This result was better than that of counterparts such as graphene hydrogel (GH) and commercial catalyst P25. The excellent cycling performance of the Hem/GH was well maintained even after multiple cycles on adsorption process and photocatalytic reaction. Interestingly, after the photodegradation of MB, a light-induced pH change of the solution from alkaline pH 8.99 to acidic pH 3.82 was observed, and 10 wt % total organic carbon remained. The liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS) analysis confirmed the generation of acidic degradation products. The photocatalytic mechanism was further investigated by trapping experiments, which revealed that the MB degradation was driven mainly by the participation of O radicals in the photocatalytic reaction. As an extended application, visually intuitive observation showed the as-prepared Hem/GH also had strong antibacterial properties. These results suggest that Hem/GH could be potentially used for practical application due to its high adsorption ability, excellent photocatalytic activity, and strong antibacterial properties.

In this work, porphyrin-based MOF nanosheets were formulated.

The design and synthesis of a novel generation of a nanoscaled platform with imaging-guided therapy remain a real challenge. It can not only improve the imaging sensitivity of tumor tissues for guiding all kinds of treatments but also reduce the harm for healthy tissues. Here, polydopamine (PDA), polyethylene glycol (PEG), and c­(RGDyK) peptide (RGD)-modified and cisplatin-loaded Gd2Hf2O7 nanoparticles (Gd2Hf2O7@PDA@PEG-Pt-RGD NPs) are designed for magnetic resonance imaging (MRI)-guided combined chemo-/photothermal-/radiotherapy of resistant tumors. The as-prepared NPs display high relaxivity (r 1 = 38.28 mM–1 s–1) as an MRI contrast agent because of their ultrasmall size and surface modification with polyacrylic acid and PDA. Gd2Hf2O7@PDA@PEG-Pt-RGD NPs exhibit pH and NIR dual-stimuli responsiveness for cisplatin release. Based on competent NIR absorption and high X-ray attenuation efficiency, Gd2Hf2O7@PDA@PEG-Pt-RGD NPs show potential photothermal effect by exposing to an 808 nm NIR laser and significantly improve the generation of reactive oxygen species after X-ray radiation. Combined chemo-/photothermal-/radiotherapy can effectively treat the resistant A549R cells, providing the enhanced therapeutic efficiency to cancer tissues and the reduced side effect to healthy tissues. Furthermore, Gd2Hf2O7@PDA@PEG-Pt-RGD NPs present no obvious toxicity during the treatment, which demonstrates the potential as an efficient MRI-guided combined chemo-/photothermal-/radiotherapy nanoplatform for drug-resistant tumors.

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