Porphyrinic Metal-organic Framework Research Articles

Engineering of upconversion carbon dots/metal-organic frameworks “Peeled Pitaya-Like” heterostructure for mitochondria-targeted photodynamic therapy

Developing of near-infrared (NIR) light triggered metal–organic frameworks (MOFs) nano-photosensitizers (nPSs) is highly desirable for photodynamic therapy (PDT) owing to its promising properties. Herein, we designed a mitochondria-targeted, 808 nm near-infrared (NIR) light-triggered upconversion carbon dots (CDs) coordinated porphyrinic MOFs (PCDs) nPSs for enhanced PDT. The system was fabricated through incorporation of sufficient ultrasmall CDs into the nanopores as well as the surface of porphyrinic porous MOFs to construct a peeled pitaya-like heterostructure, which was further functionalized with mitochondria-targeted moieties of triphenylphosphines (TPPs), termed PCDTs, for enhanced PDT. The upconversion CDs act as tremendous “antennas” to efficiently absorb NIR laser, and the tight coupling between the CDs and porphyrin in MOFs, greatly shortened the distance between the two components and improved the efficiency of the energy transfer from the CDs to porphyrinic MOFs, thus yielded a sharply enhanced 1O2 generation capability. The mitochondria-targeted ability further enhanced the ROS oxidative stress, accelerated dysfunction of mitochondria, and induced intrinsic apoptosis. Excellent anticancer ability was demonstrated by the in vitro cancer cells killing and in vivo suppression of tumor growth. This work presents a novel engineered heterostructure to combat the current limitation of MOF in PDT.

Size- and shape-dependent cytotoxicity of nano-sized Zr-based porphyrinic metal-organic frameworks to macrophages

The wide utilization of nano-sized metal-organic frameworks (NMOFs) leads to inevitable health risks to humans. Previous studies on health risks of NMOFs mainly focus on the cytotoxic tests of typical NMOFs，but lack sufficient studies on the effects of physiochemical characteristics of NMOFs on the cytotoxicity and the related mechanisms. Here, four kinds of Zr-based porphyrinic NMOFs (PCNs), including spherical 30, 90, and 180 nm PCN-224 and rod-like 90 nm PCN-222, were taken as a proof of the concept to investigate the effects of the size and shape of NMOFs on the cytotoxicity and related mechanisms to macrophages. The 30 nm spherical PCN-224 induced significant rupture of cell membrane and dissolved in lysosome, leading to the most significant cell necrosis among the studied other nano-sized PCNs. However, other studied PCNs showed insignificant membrane rupture and their dissolution in lysosome. Furthermore, the 90 nm-sized PCN-224 led to much more significant cell necrosis by inducing lysosome damage and inhibiting of autophagy flux than the rod-like 90 nm PCN-222. These findings reveal the size- and shape-dependent cytotoxicity of PCNs and the related mechanisms and are helpful to the assessment of the potential health risks of NMOFs and the safe application of NMOFs.

Rapid microwave synthesis of PCN-134-2D for singlet oxygen based-oxidative degradation of ranitidine under visible light: Mechanism and toxicity assessment

Two-dimensional porphyrin metal–organic frameworks (2D-PMOFs) showed potential applications in the field of photocatalysis. In this study, PCN-134-2D was rapidly prepared by the microwave-assisted solvothermal (MS) method for photocatalytic degradation of ranitidine (RAN), and exhibited enhanced photocatalytic performance due to the augmentation of the TCPP/BTB ratio (0.55). 93.1% of RAN could be effectively photodegraded in 120 min through PCN-134-2D under visible light. During the photosensitizing process, singlet oxygen (1O2) was proved to be the major reactive oxygen species (ROS) and showed the unique ability of non-radical resistance to conquer the inhibiting effects of inorganic anions (Cl−, HCO3−, NO3−, SO42−, H2PO4−) and natural organic matter (humic acid [HA]). The effects of practical reaction parameters were studied in detail. Light intensity and oxygen content were demonstrated as the key factors to photosensitization. The final removal rates of RAN in lake waters and river waters were 84.7% and 84.1% under the solar light. Meanwhile, the total organic carbon (TOC) removal rates were 30.4% and 31.5%, respectively. Ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS) was used to analyze the photodegradation products of the target RAN, and 17 intermediate compounds were obtained in ESI positive mode. The degradation pathways of RAN by 1O2 were proposed as C–N bond and C–S bond cleavage. Ecotoxicity assessment by the Ecological Structure Activity Relationships (ECOSAR) program indicated that most of the intermediate products were “not harmful” to fish, daphnid and green algae. The inhibition rate of Vibrio fischeri bioluminescence was approximately reduced 62% after RAN was treated by PCN-134-2D in 120 min.

Visible-Light-Driven Production of Solar Fuels Catalyzed by Nanosized Porphyrin-Based Metal–Organic Frameworks and Covalent–Organic Frameworks: A Review

Porphyrin-based materials are excellent chromophores because they strongly absorb visible light and their relatively low-energy lowest unoccupied molecular orbitals thermodynamically favor photoinduced electron transfer. They can generate charge-transfer excited states with and without cocatalyst(s) and ease energy transfer and ultrafast excitation energy migration. Combined with synthetic accessibility, these qualities make them ideal building blocks for porous metal–organic framework (MOF)- and covalent–organic framework (COF)-based photocatalysts to produce solar fuels. This review first describes the structures of the most common porphyrinic MOFs and COFs and their excited-state properties and semiconducting behavior as well as that of derived composites. The generally accepted mechanisms of formation of H2, CH4 and derivatives, and N2 are then reviewed, followed by the detailed examples of nano-MOFs and nano-COFs used for the said purpose: characteristic parameters such as rates of production, turnover numbers (TONs), turnover frequencies (TOFs), and apparent quantum efficiencies are described and compared. This shows that porphyrin-based MOFs and COFs are efficient solar-fuel-producing photocatalysts, with characteristics comparable to those of nonporphyrinic MOF and COF photocatalysts, although, on some occasions, the rates of production fall short of record values. Conversely, porphyrinic MOFs and COFs exhibit the greatest TONs and TOFs of any solar-fuel-producing MOFs or COFs but still face shortcomings concerning selectivity in CH4 production because of the many possible side products. Importantly, while the best rate of photoproduction of solar fuels has been observed from nanoscale photocatalysts, there seem to be no drastic differences in the rate (within μmol–1 h–1 and mmol g–1 h–1) between nanoscale and microscale heterogeneous photocatalysts. This observation suggests that the more active sites are mostly located at or near the surface of the particles. Overall, nanosized porphyrin-based MOFs and COFs show rich and promising photocatalytic properties for generating solar fuels but still have room for improvement.

Preparation of Photocatalytic and Antibacterial MOF Nanozyme Used for Infected Diabetic Wound Healing.

Bacterial infection has been a considerable obstacle for diabetic wound healing. A multifunctional nanoplatform used as nanozyme for bacterial infected diabetic wound is extremely attractive. Therefore, gold nanoclusters modified zirconium-based porphyrin metal-organic frameworks (Au NCs@PCN) were constructed by an in situ growth method. Through SEM, TEM, and EDS mapping, the surface of ellipsoid-shaped particles around 190 nm was observed to be evenly interspersed with 5-8 nm gold nanoclusters. Notably, Au NCs@PCN exhibits excellent performance in exciting ROS generation and photothermal effects. Under near-infrared (NIR) laser irradiation, Au NCs@PCN can be heated to 56.2 °C and produce ROS, showing an effective killing effect on bacteria. Antibacterial studies showed that Au NCs@PCN inhibited MRSA and Ampr E. coli by destroying membrane structure and inducing protein leakage up to 95.3% and 90.6%, respectively. Animal experiments showed that Au NCs@PCN treated diabetic rats had reduced wound coverage to 2.7% within 21 days. The immunoblot analysis showed that proangiogenic and proepithelial cell proliferation factors were expressed significantly up-regulated. These results prove that Au NCs@PCN with photocatalytic and nanozyme activity has a broad application prospect for promoting diabetic infected wound healing.

Glutathione responsive nitric oxide release for enhanced photodynamic therapy by a porphyrinic MOF nanosystem

In photodynamic therapy (PDT), the concentration of reactive oxygen species (ROS) generated in cells directly determines the therapeutic effect. However, excessive glutathione (GSH) concentration at the tumor site and hypoxic environment strongly reduce the production of ROS. Nitric oxide (NO) has a variety of anti-tumor activities, including the induction of cell apoptosis and sensitization to PDT, so it is in the spotlight in the area of cancer intervention. Therefore, it is very innovative to combine NO therapy with PDT and simultaneously reduce GSH content and relieve hypoxia. Metal-organic framework (MOF) is an emerging drug delivery vehicle that can exert photodynamic effects when a photosensitizer is used as its organic ligand. In this study, we constructed a GSH-responsive NO producing nanosystem to enhance ROS production through GSH depletion and hypoxia alleviation. Briefly, nicorandil (Nic) is encapsulated into porous porphyrinic MOF nanoparticles, and hyaluronic acid (HA) is electrostatically adsorbed on the surface of the MOF nanoparticles for CD44 receptor-targeting and prevention of Nic leakage. Notably, the Nic reacts with GSH to produce NO gas with vasodilation and GSH reduction, thus improving oxygen supply for efficient ROS generation. Moreover, the generated NO can further react with superoxide radical anion to produce highly reactive peroxynitrite (ONOO−) molecules with higher cytotoxicity. Overall, the Nic-MOF@HA nanosystem combines NO gas therapy with PDT, resulting in a significant increase in ROS production and greatly enhancing the efficacy of PDT.

Two-stage ligand exchange in Mn(III)-based porphyrinic metal−organic frameworks for fluorescence water sensing

Metal−organic frameworks (MOFs) have emerged as promising materials for smart sensing and imaging applications. Here, a novel micron-biscuit Mn(III)-based porphyrinic MOF is synthesized with the modulation of 4,4′-biphenyldicarboxylic acid (BPDC). The anisotropic growth of MOF is induced by the increased steric hindrance, yielding micron-biscuit Mn-TCPP(BPDC) MOF crystals. Mn(III), as a sealer, quenched the intrinsic fluorescence of porphyrin because of the ligand-to-metal charge transfer (LMCT) effect, and this disappeared fluorescence can be regularly restored and enhanced due to LMCT effect inhibition and release of free porphyrin derived from the water-induced two-stage ligand exchange (TSLE) between BPDC, porphyrin and water. The as-prepared MOF acts as an excellent “signal-on” luminescent water-sensing probe with low amount (2.5 μg/mL) that can efficiently realize the trace detection of water in various organic media with high sensitivity, especially in dimethyl sulfoxide (DMSO), the detection limit is as low as 0.04% (v/v). Moreover, Mn-TCPP(BPDC) was successfully used for sensing water content in real commercial samples. This MOF with the guest-induced TSLE not only provides inspiration for the design of new luminescent materials, but also widens the path for smart sensing.

Regulation of the Structure of Zirconium-Based Porphyrinic Metal-Organic Framework as Highly Electrochemiluminescence Sensing Platform for Thrombin.

An electrochemiluminescence (ECL) sensor provides a sensitive and convenient method for early diagnosis of diseases; however, it is still a challenge to develop simple and sensitive sensing platforms based on efficient ECL signals and luminophore groups. Porphyrin-based metal-organic frameworks (MOFs) show great potential in ECL sensing; however, the mechanism and structure-activity relationship, as well as application, are rarely reported. Herein, hydrothermal reactions obtained porphyrin Zr-MOFs (PCN-222) with different specific surface areas, pore sizes, structures, and surface charge states by tuning the reaction time were developed, which served both as the ECL luminophore, coreaction promoter for S2O82-, and a connection in the ECL immunoassay. By progressively controlling the condition of the hydrothermal reaction, PCN-222 with large surface area-abundant micropores can be obtained, which has good conductivity and positively charged surfaces, obtaining excellent ECL performance. The ECL performance and the enhancement mechanism were investigated in detail. Using PCN-222-6h with the best ECL intensity as the immobilization matrix for the aptamer, a highly sensitive and selective assay for thrombin was developed. The decrease of the ECL signal was logarithmically linear with the concentration of thrombin in the range from 50 fg mL-1 to 100 pg mL-1 with a low detection limit of 2.48 fg/mL. This proposed strategy provides a brand new approach for tuning of the structures of MOFs as effective ECL signal probes, thus providing wider possibilities for effective ECL immunoassays in the detection of other biomarkers in diagnosis of diseases.

Light-Enhanced Osmotic Energy Harvester Using Photoactive Porphyrin Metal-Organic Framework Membranes.

High ion selectivity and permeability, as two contradictory aspects for the membrane design, highly hamper the development of osmotic energy harvesting technologies. Metal-organic frameworks (MOFs) with ultra-small and high-density pores and functional surface groups show great promise in tackling these problems. Here, we propose a facile and mild cathodic deposition method to directly prepare crack-free porphyrin MOF membranes on a porous anodic aluminum oxide for osmotic energy harvesting. The abundant carboxyl groups of the functionalized porphyrin ligands together with the nanoporous structure endows the MOF membrane with high cation selectivity and ion permeability, thus a large output power density of 6.26 W m-2 is achieved. The photoactive porphyrin ligands further lead to an improvement of the power density to 7.74 W m-2 upon light irradiation. This work provides a promising strategy for the design of high-performance osmotic energy harvesting systems.

Light‐Enhanced Osmotic Energy Harvester Using Photoactive Porphyrin Metal–Organic Framework Membranes

AbstractHigh ion selectivity and permeability, as two contradictory aspects for the membrane design, highly hamper the development of osmotic energy harvesting technologies. Metal–organic frameworks (MOFs) with ultra‐small and high‐density pores and functional surface groups show great promise in tackling these problems. Here, we propose a facile and mild cathodic deposition method to directly prepare crack‐free porphyrin MOF membranes on a porous anodic aluminum oxide for osmotic energy harvesting. The abundant carboxyl groups of the functionalized porphyrin ligands together with the nanoporous structure endows the MOF membrane with high cation selectivity and ion permeability, thus a large output power density of 6.26 W m−2 is achieved. The photoactive porphyrin ligands further lead to an improvement of the power density to 7.74 W m−2 upon light irradiation. This work provides a promising strategy for the design of high‐performance osmotic energy harvesting systems.

Mesoporous porphyrinic metal-organic framework nanoparticles/3D nanofibrous scaffold as a versatile platform for bone tumor therapy

Removal of residual tumor cells and regeneration of large bone defects are urgently required after surgical resection of bone tumors. To address these issues, a bifunctional scaffold with high photothermal effect and osteogenesis was developed for bone tumor therapy. Sintered mesoporous imidazolate framework 8 (ZIF8) nanoparticles with porphyrin-like macrocycles were synthesized by calcination of ZIF8 precursors under an N2 atmosphere. The prepared ZIF8 possesses good photothermal efficacy and drug loading capability. Phenamil (Phe), an activator of bone morphogenetic protein pathways, was encapsulated into ZIF8 before loading onto gelatin nanofibrous (GF) scaffolds. The loaded Phe exhibited sustained and near-infrared triggered release profiles, which is capable of promoting bone morphogenetic protein 2 induced osteogenic differentiation even under near-infrared treatment. Moreover, our studies revealed that the photothermal effect of GF/ZIF8-Phe scaffolds can kill MG-63 cells in vitro and inhibit subcutaneous tumor growth in vivo. Therefore, the GF/ZIF8-Phe scaffold represents a novel bifunctional platform for tumor therapy and bone regeneration.

Engineering a curcumol-loaded porphyrinic metal-organic framework for enhanced cancer photodynamic therapy

Photodynamic therapy (PDT), a non-invasive and safe treatment, is a clinical promising alternative strategy for certain cancers. Although PDT can trigger tumor specific immunity, the immunosuppressive tumor microenvironment severely limits the efficacy of photodynamic immunotherapy. Curcumol (CUR), extracted from essential oils of traditional Chinese medicine, has potential immune activation effect for cancer immunotherapy. Considering the fat solubility and volatility hinder the in vivo application of essential oils, a metal-organic framework system (Named as CuTPyP/F68) composed of porphyrin and Cu2+ was constructed for delivering CUR (Named as CUR@CuTPyP/F68). The in vitro assays proved that CUR@CuTPyP/F68 could directly kill tumor cells by the released CUR and singlet oxygen (1O2) generated under laser irradiation (marked as ‘+’). Moreover, CUR@CuTPyP/F68 had superior tumor targeting and retention capabilities, which effectively inhibited tumor growth in vivo with only a single dose. Finally, the mechanism of CUR-mediated enhanced PDT had been firstly proposed: (1) CUR@CuTPyP/F68(+)-treated group exhibited more CD4+ and CD8+ T cells infiltration in tumor tissue; (2) CUR@CuTPyP/F68(+)-treated group exhibited high level of IFN-γ, IL-12 and TNF-α in blood. Overall, we believe the PDT-immunotherapy strategy has great potential for the treatment of breast cancer, and this work will provide a reference for the clinical application of essential oils in cancer immunotherapy.

Upconverted/downshifted NaLnF4 and metal-organic framework heterostructures boosting NIR-II imaging-guided photodynamic immunotherapy toward tumors

Heterostructures of NaLnF4 and porphyrinic metal-organic frameworks (MOF) have been reported as a promising platform for near-infrared (NIR)-driven photodynamic therapy (PDT), while the energy transfer from NaLnF4 to MOF greatly decreased the upconversion emissions. To develop NaLnF4 and MOF heterostructures with significantly improved PDT and imaging simultaneously is important to track their location to implement therapy accurately. Herein, we constructed Er3+-doped NaLnF4@MOF core@shell nanoparticles to integrate NIR-driven PDT and NIR-II imaging. NaLnF4 nanoparticles are designed with upconversion and NIR emission simultaneously under a single 980 nm excitation, where the upconversion luminescence (UCL) overlaps well with the absorption of Zr-based porphyrin MOF, enabling efficient energy transfer from NaLnF4 to the MOF shell to generate 1O2. And the NIR luminescence, which gave out under a lower excitation power than that of UCL, could be used to track the location and distribution of the heterostructures via NIR-II imaging. Moreover, antiprogrammed death-ligand 1 (α-PD-L1) immunotherapy was introduced synergistically to improve antitumor immunity efficacy. The combination of NaLnF4@MOF and α-PD-L1 not only inhibited primary tumors but also suppressed distant one, leading to an effective tumor inhibition rate of 95%. This work provides an integrated nanoplatform for boosting NIR-II imaging-guided PDT/immunotherapy efficacy toward tumor treatment.

Novel 2D Zn-porphyrin metal organic frameworks revived CdS for photocatalysis of hydrogen production

The main challenge of photocatalysis is how to improve the coefficient of utilization and conversion rate for solar energy. Herein, we report a composite photocatalyst related to a novel porphyrin metal organic frameworks (MOFs), in which cadmium sulfide nanoparticles (CdS NPs) are grown in situ on the surface of two-dimensional (2D) zinc porphyrin nanosheets (Zn-TCPP NSs) by hydrothermal method. Interestingly, Zn-TCPP NSs and CdS NPs form a Type II heterojunction structure, which reduces the photogenerated electron-hole recombination rate of CdS. Moreover, in the near-infrared region, the photo-excited electrons generated by Zn-TCPP NSs are transmitted to CdS NPs, so that cadmium sulfide can realize both visible light and near-infrared light for photocatalytic hydrogen production. The Zn-TCPP NSs not only has excellent light absorption capacity, but also has a unique frame design that effectively reduces the recombination rate of photoinduced electron hole pairs, thus improving the conversion rate of solar energy. As expected, the photocatalytic performance of the porphyrin MOFs modified materials is significantly enhanced compared to CdS NPs. The hydrogen production rate of the Pt@CdS NPs/Zn-TCPP NSs(C-Z-T) composite material in the visible light region is about 15.3 mmol g −1 h −1 , which is 11 times for Pt@CdS NPs. Furthermore, the Pt@CdS NPs/Zn-TCPP NSs(C-Z-T) also has a considerable hydrogen production rate in the near-infrared region, such as 200 μmol g −1 h −1 at 600 nm, 90 μmol g −1 h −1 at 765 nm and 20 μmol g −1 h −1 at > 800 nm. • Provides an idea to simultaneously produce hydrogen in visible light and near-infrared light. • Zn porphyrin MOF has a strong ability to separate photogenerated carriers. • The hydrogen production rate of the composite material under visible light is 11 times more than pure CdS.

Fluorescent Imaging-Guided Chemo- and Photodynamic Therapy of Hepatocellular Carcinoma with HCPT@NMOFs-RGD Nanocomposites.

BackgroundHepatocellular carcinoma (HCC), arising from hepatocytes, is the most common primary liver cancer. It is urgent to develop novel therapeutic approaches to improve the grim prognosis of advanced HCC. 10-hydroxycamptothecin (HCPT) has good antitumor activity in cells; however, its hydrophobicity limits its application in the chemotherapy of HCC. Recently, nanoscale porphyrin metal-organic frameworks have been used as drug carriers due to their low biotoxicity and photodynamic properties.MethodsNanoscale zirconium porphyrin metal-organic frameworks (NMOFs) were coated with arginine-glycine-aspartic acid (RGD) peptide to prepare NMOFs-RGD first. The HepG2 cell line, zebrafish embryos and larvae were used to test the biotoxicity and fluorescence imaging capability of NMOFs-RGD both in vitro and in vivo. Then, NMOFs were used as the skeleton, HCPT was assembled into the pores of NMOFs, while RGD peptide was wrapped around to synthesize a novel kind of nanocomposites, HCPT@NMOFs-RGD. The tissue distribution and chemo- and photodynamic therapeutic effects of HCPT@NMOFs-RGD were evaluated in a doxycycline-induced zebrafish HCC model and xenograft mouse model.ResultsNMOFs-RGD had low biotoxicity, good biocompatibility and excellent imaging capability. In HCC-bearing zebrafish, HCPT@NMOFs-RGD were specifically enriched in the tumor by binding specifically to integrin αvβ3 and led to a reduction in tumor volume. Moreover, the xenografts in mice were eliminated remarkably following HCPT@NMOFs-RGD treatment with laser irradiation, while little morphological change was found in other main organs.ConclusionThe nanocomposites HCPT@NMOFs-RGD accomplish tumor targeting and play synergistic chemo- and photodynamic therapeutic effects on HCC, offering a novel imaging-guided drug delivery and theranostic platform.

Encapsulation of Polymetallic Oxygen Clusters in a Mesoporous/Microporous Thorium-Based Porphyrin Metal-Organic Framework for Enhanced Photocatalytic CO2 Reduction.

Solar-initiated CO2 reduction is significant for green energy development. Herein, we have prepared a new mesoporous/microporous porphyrin metal-organic framework (MOF), IHEP-20, loaded with polymetallic oxygen clusters (POMs) to form a composite material POMs@IHEP-20 for visible-light-driven photocatalytic CO2 reduction. The as-made composite material exhibits good stability in water from pH 0 to 11. After POMs were introduced to IHEP-20, they showed superior activity toward photocatalytic CO2 reduction with a CO production rate of 970 μmol·g-1·h-1, which is 3.27 times higher than that of pristine IHEP-20. This study opens a new door for the design and synthesis of high-performance catalysts for the photocatalytic reduction of CO2.

A novel fluorescence sensor based on Zn porphyrin MOFs for the detection of bisphenol A with highly selectivity and sensitivity

In this study, we designed a zinc-based porphyrin metal-organic framework (Zn-TCPP-MOF) for ultra-sensitive and quantitative detecting BPA as a novel luminescent sensor. The fluorescence experiments revealed that the detectable limit of Zn-TCPP-MOF against BPA was far lower than many other reportorial methods. Moreover, an apparent quenching merely occurs when Zn-TCPP-MOF encountered BPA compared with the other phenolic compounds that usually coexist with BPA in food plastic packaging and it will not be interfered as well. During the adsorption experiments, the Zn-TCPP-MOF exhibited the most evident adsorption performance for BPA, the zeta potential tests showed the other phenolic compounds could not significantly change the surface potential of Zn-TCPP-MOF except BPA. The highly sensitive and selective fluorescence quenching mechanism as follow, the structural characteristics of BPA and Zn-TCPP-MOF make them conducive to electrostatic interaction that strengthens the adsorption of Zn-TCPP-MOF to BPA. Furthermore, based on cyclic voltammetry (CV) and Kubelka-Munk diagram to calculate molecular orbital energies, we found that the excited state of the ligand (TCPP) in MOFs is at a higher energy level than the LUMO of BPA which allows existing a driving force for the transfer of excited electrons from TCPP to BPA, thus promote the occurrence of luminescence quenching. • A novel MOF with defined structure and fluorescence properties was synthesized. • A highly sensitive sensor designed for BPA detection with a LOD of 0.902 nM. • Two hydroxyl anions of BPA are easily coordinated with zinc ions . • Two benzene rings on BPA make it generates strong interaction with porphyrin . • This sensor has also achieved satisfactory recoveries in practical application .

2D Ti-based metal–organic framework photocatalysis for red light-driven selective aerobic oxidation of sulfides

Ti-based metal-organic frameworks (MOFs) consisting of organic linkers and Ti-oxo clusters have tremendous proneness in visible light photocatalysis. Here, two-dimensional (2D) Ti-based porphyrin MOF (PMOF (Ti)) and bulk PMOF (Ti) were synthesized and fully characterized. Consequently, the porphyrin linker imparts broad absorption of visible light and the appropriate reduction potential of Ti‐oxo clusters can activate O2 to superoxide (O2•–). The 2D PMOF (Ti) exhibits more satisfying results for the red light-driven selective oxidation of sulfides with O2 than bulk PMOF (Ti). In addition, 2D PMOF (Ti) is highly robust which could be recycled 8 times without any loss of photocatalytic activity. Mechanistic investigations reveal that O2•– is the crucial reactive oxygen species (ROS) in forming sulfoxides with high selectivities. This work highlights that 2D MOFs could have a great potential in selective photocatalytic transformations of organic molecules.

Copper porphyrin metal-organic framework modified carbon paper for electrochemical sensing of glyphosate

Glyphosate (GLY), an exceedingly effective herbicide, has raised worries about the risks posing to the ecosystem and human health due to excessive exposure. An electrochemical sensor based on copper porphyrin metal organic framework and gold nanoparticles modified carbon paper (Cu-TCPP/AuNPs/CP) was developed for sensitive determination of GLY by differential pulse voltammetry (DPV). The Cu-TCPP has large surface area and excellent catalytic activity, increasing the copper sites to combine with GLY for selective determination and improving the sensitivity of the electrochemical sensor. Under optimized conditions, the constructed sensor has a linear range from 0.2 to 120 μmol L−1 with a detection limit of 0.03 μmol L−1 (S/N = 3). The sensor was applied to water, soybean, wheat and carrot with the recovery ranging from 97.5% to 110.7%. After two weeks storage at 4 °C, the peak current of the sensor remains 86.6% of the original value with negligible interference. This sensor has a great potential application in water, soil and other environmental samples.

Construction of Electrochemical and Photoelectrochemical Sensing Platform Based on Porphyrinic Metal-Organic Frameworks for Determination of Ascorbic Acid.

Highly sensitive and specific detection of biomolecular markers is of great importance to the diagnosis and treatment of related diseases. Herein, Cu-TCPP@MOFs thin films were synthesized with tetrakis(4-carboxyphenyl) porphyrin (H2TCPP) as organic ligands and copper ions as metal nodes. The as-synthesized Cu-TCPP@MOFs thin films as electrode modifiers were used to modify the pre-treated glassy carbon electrode (GCE) and the electrochemical performances of Cu-TCPP@MOFs/GCE were evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Furthermore, as the working electrode, the constructed Cu-TCPP@MOFs/GCE was used for the investigation of ascorbic acid (AA) due to its outstanding electrocatalytic activities towards AA by several electrochemical methods, including cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CA). The well-linear relationship was established based on different AA concentration ranges and the ideal detection limits (LOD) were obtained in the above-mentioned electrochemical methods, respectively. Furthermore, a Cu-TCPP MOFs@GCE sensing platform was used as a photoelectrochemical (PEC) sensor to quantitatively detect AA based on the strong absorption properties of Cu-TCPP ingredients in Cu-TCPP MOFs in a visible light band of 400~700 nm. PEC sensing platform based on Cu-TCPP@MOFs exhibited a more extensive linear concentration range, more ideal detection limit, and better sensitivity relative than the other electrochemical methods for AA. The well linear regression equations were established between the peak current intensity and AA concentrations in different electrochemical technologies, including CV, DPV, and CA, and PEC technology. AA concentration ranges applicable to various electrochemical equations were as follows: 0.45~2.10 mM of CV, 0.75~2.025 mM of DPV, 0.3~2.4 mM of CA, 7.5~480 μM of PEC, and the corresponding detection limits for AA were 1.08 μM (S/N = 3), 0.14 μM (S/N = 3), 0.049 μM (S/N = 3), and 0.084 nA/μM. Moreover, the proposed Cu-TCPP MOFs@GCE electrochemical and photoelectrochemical sensing platform was applied to determine the AA concentration of a real human serum sample; the results reveal that Cu-TCPP MOFs@GCE sensing platform could accurately determine the concentration of AA of the human serum under other potential interferences contained in the human serum samples.