Integrin αvß3 and LHRH Receptor Double Directed Nano-Analogue Effective Against Ovarian Cancer in Mice Model.

Introduction: The high mortality rate of malignant ovarian cancer is attributed to the absence of effective early diagnosis methods. The LHRH receptor is specifically overexpressed in most ovarian cancers, and the integrin αvß3 receptor is also overexpressed on the surface of ovarian cancer cells. In this study, we designed LHRH analogues (LHRHa)/RGD co-modified paclitaxel liposomes (LHRHa-RGD-LP-PTX) to target LHRH receptor-positive ovarian cancers more effectively and enhance the anti-ovarian cancer effects. Methods: LHRHa-RGD-LP-PTX liposomes were prepared using the thin film hydration method. The morphology, physicochemical properties, cellular uptake, and cell viability were assessed. Additionally, the cellular uptake mechanism of the modified liposomes was investigated using various endocytic inhibitors. The inhibitory effect of the formulations on tumor spheroids was observed under a microscope. The co-localization with lysosomes was visualized using confocal laser scanning microscopy (CLSM), and the in vivo tumor-targeting ability of the formulations was assessed using the IVIS fluorescent imaging system. Finally, the in vivo anti-tumor efficacy of the formulations was evaluated in the armpits of BALB/c nude mice. Results: The results indicated that LHRHa-RGD-LP-PTX significantly enhanced cellular uptake in A2780 cells, increased cytotoxicity, and hand a more potent inhibitory effect on tumor spheroids of A2780 cells. It also showed enhanced co-localization with endosomes or lysosome in A2780 cells, improved tumor-targeting capability, and demonstrated an enhanced anti-tumor effect in LHRHR-positive ovarian cancers. Conclusion: The designed LHRHa-RGD-LP-PTX liposomes significantly enhanced the tumor-targeting ability and therapeutic efficacy for LHRH receptor-positive ovarian cancers.

Construction of a highly stable natural silicate-supported molybdenum catalyst for efficient epoxidation of olefins.

Epoxides are important bulk chemicals, playing irreplaceable role in the chemical industry, but facing serious pollution and low productivity in the production process. Therefore, the development of green and efficient epoxidation of olefins by stable catalysts with low prices is of great significance. In this study, a Mo-MATP catalyst was prepared by modifying Mo(CO)6 on attapulgite through Si-O bonding. Mo-MATP exhibits excellent performance (99% yield of cyclooctane oxide, CYCO) and stability (80% selectivity of CYCO after 17 cycles), highly tert-butyl hydroperoxide (TBHP) utilization, and extensive substrate scalability. Furthermore, the in-situ Fourier Transform Infrared Spectroscopy (FT-IR), Electron Spin-resonance Spectroscopy (ESR) and High Resolution Mass Spectrometry (HRMS) spectra suggest that TBHP would be activated by Mo-MATP to generate peroxyl radicals, which then oxidize alkenes to their corresponding epoxides. In this study, the stable loading of Mo would largely solve the problem of Mo loss during the catalytic process, thus providing a stable and dispersed Mo active center, enabling the catalyst to possess high catalytic performance and recycling stability.

Correction: Tubular metal organic frameworks from the curvature of 2D-honeycombed metal coordination.

Correction for 'Tubular metal organic frameworks from the curvature of 2D-honeycombed metal coordination' by Junhui Bao et al., Dalton Trans., 2020, 49, 2403-2406, https://doi.org/10.1039/C9DT04668B.

Visible light driven reform of wasted plastics to generate green hydrogen over mesoporous ZnIn2S4.

As the global consumption of plastics keeps increasing, the accumulated plastics in the natural environment have threatened the survival of human beings. Photoreforming, as a simple and low-energy way, could transform wasted plastic into fuel and small organic chemicals at ambient temperature. However, the previously reported photocatalysts have some drawbacks, such as low efficiency, containing precious or toxic metal. Herein, a noble-free, non-toxic, and easy prepared mesoporous ZnIn2S4 photocatalyst has been applied in photoreforming of polylactic acid (PLA), polyethylene terephthalate (PET) and polyurethane (PU), generating small organic chemicals and H2 fuel under simulated sunlight. Plastic was degraded into small organic molecules after the pretreatment, which futher acted as the substrate for photoreforming. Mesoporous ZnIn2S4 exhibits high H2 production efficiency, strong redox ability, and long-term photostability. Furthermore, mesoporous ZnIn2S4 could overcome the hindrances of dyes and additives of realistic wasted plastic bags and bottles with high decomposition efficiency, providing an efficient and sustainable strategy for the upcycling of wasted plastics.

Tuning the olefin-VOCs epoxidation performance of ceria by mechanochemical loading of coinage metal.

Under the background of carbon dioxide emission reduction, how to realize the treatment and the high value-added conversion of typical olefin volatile organic compounds (olefin-VOCs), such as styrene, is a big challenge. In this contribution, the ceria-supported coinage metal catalysts (M/CeO2, M = Au, Ag, and Cu) are successfully synthesized by a dry mechanochemical method, and their catalytic performance for styrene-VOC epoxidation with tert-butyl hydrogen peroxide (TBHP) as an oxidant to prepare high-value styrene oxide (SO) is investigated. The oxygen vacancies of ceria play a key role in the anchoring of metal nanoparticles. After ball milling, Au(III) is partially reduced and coexists on ceria in two valence states (Au3+ and Au0), and the reactive oxygen species of the as-prepared catalyst are enhanced. The catalytic behaviors, including solvents effect, substrate concentration, oxidant ratio, catalyst dosage, reaction time, and temperature, are systematically investigated. Au/CeO2 exhibits good styrene epoxidation performance with a total styrene conversion of 94% and a SO yield of 63%, along with good reusability and substrate scalability. Thermodynamics and kinetics show that Au/CeO2 was more favorable for styrene epoxidation and this reaction is dominated by the rate of intrinsic chemical reactions on the surface of the catalyst. Based on experimental discussions and a set of characterizations (XPS, XRD, in-situ FT-IR, ESR, ESI-HSMS, etc.), the mechanism is revealed as the synergistic catalysis between the reactive oxygen species of Au/CeO2 and the peroxide radicals generated by the homolysis of TBHP.

Time-resolved EPR revealed C(sp3)-H activation through a photo-enhanced phthalimide-N-oxyl (PINO) radical.

The time-resolved electron paramagnetic resonance (EPR) technique under operando photochemical conditions as an efficient strategy to investigate the fast formation of abundant long-lived PINO radicals (t1/2 = 204 s) and their activation of the C(sp3)-H process has been researched. This developed method offers a pathway for investigating the properties and tracking the transformations of radical species in the photoredox reaction process.

Biomimetic catalytic aerobic oxidation of C-sp(3)-H bonds under mild conditions using galactose oxidase model compound CuIIL.

Developing highly efficient catalytic protocols for C-sp(3)-H bond aerobic oxidation under mild conditions is a long-desired goal of chemists. Inspired by nature, a biomimetic approach for the aerobic oxidation of C-sp(3)-H by galactose oxidase model compound CuIIL and NHPI (N-hydroxyphthalimide) was developed. The CuIIL-NHPI system exhibited excellent performance in the oxidation of C-sp(3)-H bonds to ketones, especially for light alkanes. The biomimetic catalytic protocol had a broad substrate scope. Mechanistic studies revealed that the CuI-radical intermediate species generated from the intramolecular redox process of CuIILH2 was critical for O2 activation. Kinetic experiments showed that the activation of NHPI was the rate-determining step. Furthermore, activation of NHPI in the CuIIL-NHPI system was demonstrated by time-resolved EPR results. The persistent PINO (phthalimide-N-oxyl) radical mechanism for the aerobic oxidation of C-sp(3)-H bond was demonstrated.

A metal-free hydroxyl functionalized quaternary phosphine type ionic liquid polymer for cycloaddition of CO2 and epoxides.

Quaternary phosphine type hypercrosslinked polymer catalysts were successfully prepared using the Friedel-Crafts alkylation reactions, which benefit from the synergistic effects between the Brønsted acidity of the hydroxyl group and nucleophilicity of the Br- group as well as the CO2 capture of the ionic liquids. The as-obtained metal-free catalysts facilitate the cycloaddition and synthesis of high value-added fine chemicals.

Enhanced oxygen transfer over bifunctional Mo-based oxametallacycle catalyst for epoxidation of propylene.

Activation of inert propylene to produce propylene oxide (PO) is critical, but still faces some challenges in realizing higher PO selectivity and productivity. Herein, a temperature-controlled phase transfer catalyst (MoOO·DMF) is prepared for the liquid-phase epoxidation of propylene with tert-butyl hydroperoxide (TBHP) as oxidant, which exhibit the selectivity of 90.6% and the productivity of 1286.42·h-1 for PO (catalyst/propylene = 0.77 mol‰). Some experimental factors (solvent types, reaction temperature, contact time, the dosage of catalyst, TBHP and substrate) were investigated, and the reaction kinetics and thermodynamics are discussed. MoOO·DMF has the characteristic of both homogeneous and heterogeneous catalysts, which can be dissolved in the solvent at higher temperatures and separated from the solvent after reaction by lowering the temperature. Importantly, MoOO·DMF has a wonderful epoxidation performance for many olefins (e.g., light olefins, linear α-olefins, cyclic olefins and others). The mechanisms are proved by in-situ FT-IR, ESR and HRMS spectrum to be the selective oxygen transfer from tert-butyl peroxide radical and the MoOO bridge in MoOO·DMF to propylene. Density functional theory (DFT) calculations show that the MoOO bridge in catalyst is the key role for the activation of both the OH bond in TBHP and the CC bond in propylene, thus enhanced the epoxidation of propylene.

TiO2 nanotube arrays sensitized by copper (II) porphyrins with efficient interfacial charge transfer for the photocatalytic degradation of 4-nitrophenol.

In this paper, photocatalysts based on TiO2 nanotubes (TNTs) and TiO2 nanotube arrays (TNTAs) sensitized by Cu(II) meso-tetrakis(N-ethylpyridinium-4-yl) porphyrin (CuTEPyP) were synthesized and their structures were characterized by various analytical methods. The photocatalytic activities of both composites were then investigated through degradation of 4-nitrophenol (4-NP) in aqueous solutions under visible light irradiation. It was found that CuTEPyP/TNTAs could eliminate 95% 4-NP within 4 h, which was considerably higher than the yield obtained with CuTEPyP/TNTs (56%) under the same conditions. Compared to CuTEPyP/TNTs, the improved photocatalytic activity of CuTEPyP/TNTAs can be ascribed to increased light absorption, high separation rate of photo-generated charge pairs, and efficient charge transfer. A plausible photocatalytic degradation mechanism involving hydroxyl radicals, superoxide radical anions and singlet oxygen species was also proposed. This work presents an efficient paradigm for eliminating 4-NP under visible light irradiation.

Combined integrin αvß3 and lactoferrin receptor targeted docetaxel liposomes enhance the brain targeting effect and anti-glioma effect.

The integrin αvß3 receptor and Lactoferrin receptor (LfR) are over-expressed in both cerebral microvascular endothelial cells and glioma cells. RGD tripeptide and Lf can specifically bind with integrin αvß3 receptor and LfR, respectively. In our study, RGD and Lf dual-modified liposomes loaded with docetaxel (DTX) were designed to enhance the brain targeting effect and treatment of glioma. Our in vitro studies have shown that RGD-Lf-LP can significantly enhance the cellular uptake of U87 MG cells and human cerebral microvascular endothelial cells (hCMEC/D3) when compared to RGD modified liposomes (RGD-LP) and Lf modified liposomes (Lf-LP). Free RGD and Lf competitively reduced the cellular uptake of RGD-Lf-LP, in particular, free RGD played a main inhibitory effect on cellular uptake of RGD-Lf-LP in U87 MG cells, yet free Lf played a main inhibitory effect on cellular uptake of RGD-Lf-LP in hCMEC/D3 cells. RGD-Lf-LP can also significantly increase penetration of U87 MG tumor spheroids, and RGD modification plays a dominating role on promoting the penetration of U87 MG tumor spheroids. The results of in vitro BBB model were shown that RGD-Lf-LP-C6 obviously increased the transport of hCMEC/D3 cell monolayers, and Lf modification plays a dominating role on increasing the transport of hCMEC/D3 cell monolayers. In vivo imaging proved that RGD-Lf-LP shows stronger targeting effects for brain orthotopic gliomas than that of RGD-LP and Lf-LP. The result of tissue distribution confirmed that RGD-LF-LP-DTX could significantly increase brain targeting after intravenous injection. Furthermore, RGD-LF-LP-DTX (a dose of 5 mg kg-1 DTX) could significantly prolong the survival time of orthotopic glioma-bearing mice. In summary, RGD and LF dual modification are good combination for brain targeting delivery, RGD-Lf-LP-DTX could enhance brain targeting effects, and is thus a promising chemotherapeutic drug delivery system for treatment of glioma.

Dynamic Covalent Bonds of Si-OR and Si-OSi Enabled A Stiff Polymer to Heal and Recycle at Room Temperature.

As stiff polymers are difficult to self-heal, the balance between polymers' self-healing ability and mechanical properties is always a big challenge. Herein, we have developed a novel healable stiff polymer based on the Si-OR and Si-OSi dynamic covalent bonds. The self-healing mechanism was tested and proved by the small molecule model experiments and the contrast experiments of polymers. This polymer possesses excellent tensile, bending properties as well as room temperature self-healing abilities. Moreover, due to the sticky and shapeable properties under wetting conditions, the polymer could be used as an adhesive. Besides, even after four cycles of recycling, the polymer maintains its original properties, which meets the requirements of recyclable materials. It was demonstrated that the polymer exhibits potential application in some fields, such as recyclable materials and healable adhesives.

Biomimetic Aerobic Epoxidation of Alkenes Catalyzed by Cobalt Porphyrin under Ambient Conditions in the Presence of Sunflower Seeds Oil as a Co-Substrate.

In this work, a mild and sustainable catalytic aerobic epoxidation of alkenes catalyzed by cobalt porphyrin was performed in the presence of sunflower seeds oil. Under ambient conditions, the conversion rate of trans-stilbene reached 99%, and selectivity toward epoxide formation was 88%. The kinetic studies showed that the aerobic epoxidation followed the Michaelis-Menten kinetics. Mass spectroscopy and in situ electron spin resonance indicated that linoleic acid was converted to fatty aldehydes via hydroperoxide intermediates. A plausible mechanism of epoxidation of alkenes was accordingly proposed.

Tubular metal organic frameworks from the curvature of 2D-honeycombed metal coordination.

A tubular MOF with adequate active sites is prepared by the bending of metal-coordinated honeycombed frameworks via titration and shows fast catalytic kinetics with lower catalytic loading for CO2 conversion. The TON is observed to be 2300 and the corresponding TOF of up to 173 h-1 is achieved for the first time.

Efficient Selective Removal of Pb(II) by Using 6-Aminothiouracil-Modified Zr-Based Organic Frameworks: From Experiments to Mechanisms.

We report an efficient, reusable, and selective 6-aminothiouracil (ATA)-modified Zr(IV)-based adsorbent (defined as UiO-66-ATA(Zr)) for lead ion removal in water. The adsorption equilibrium time and the maximum sorption capacity of UiO-66-ATA(Zr) for Pb(II) are, respectively, 120 min and 386.98 mg/g at pH 4 and 298 K. The Pb(II) removal rate reaches 96% at 60 min and exceeds 99% at the equilibrium state in the pH range of 2.0-5.8. Hill and pseudo-second-order models can well describe the sorption process. Pb(II) adsorbing onto UiO-66-ATA(Zr) is an irreversible, favorable chemisorption process with multimolecule participation and film diffusion control. The calculations of density functional theory, the experimental results, and the characterization analyses suggest that the binding mechanisms are the chelation and ion-exchange/electrostatic interactions between hydroxyl/amino/sulfhydryl groups of UiO-66-ATA(Zr) and Pb(II). Besides, UiO-66-ATA(Zr) has a better affinity to Pb(II) than the coexisting ions in water and an excellent repeatability at eight cycles of adsorption. Moreover, the thermodynamic study shows that UiO-66-ATA(Zr) adsorbing Pb(II) is an endothermic reaction. Thus, UiO-66-ATA(Zr) is a prospective sorbent for Pb(II) removal under the initiative of environmental protection and water purification, and this work may also provide an idea for industrial catalysis.

Hybridization of CuO with Bi2MoO6 Nanosheets as a Surface Multifunctional Photocatalyst for Toluene Oxidation under Solar Irradiation.

Herein, CuO/Bi2MoO6 hybrid nanosheets were prepared as a surface multifunctional photocatalyst for gas-phase toluene oxidation with high conversion (>99%). Aberration-corrected scanning transmission electron microscopy suggested that CuO species were highly dispersed on the nanosheets. X-ray absorption fine structure spectra indicated that the distorted and stretched Cu-O coordination structures in CuO/Bi2MoO6 nanosheets would provide open active sites. In situ Fourier transform infrared and density functional theory results showed that toluene molecules could be chemisorbed and activated on the active sites of CuO/Bi2MoO6 nanosheets by the C-H group forming CuO/Bi2MoO6···Ph-CH3 surface complex compounds. These would induce electron-hole transfer and initiate photocatalytic reactions under visible light irradiation. The corresponding intermediates of benzaldehyde and benzoic acid would be detected by in situ diffuse reflectance infrared Fourier transform spectroscopy. Furthermore, the synergistic effect of CuO and Bi2MoO6 nanosheets could monitor charge dynamics to facilitate their respective transmission from photoexcitation sites to active centers. This work provides new insights into the essence of visible-light-driven surface photocatalysis and is expected to promote the design of novel and more effective photocatalysts at the molecular level.

Preparation of cytochrome P450 enzyme-cobalt phosphate hybrid nano-flowers for oxidative coupling of benzylamine.

A novel hybrid material with flower-mimicking morphology was fabricated with a facile coprecipitation method, and cytochrome P450 enzyme and cobalt phosphate were employed as organic and inorganic components, respectively. The hybrid nano-flowers showed excellent catalytic performance in the oxidative coupling of benzylamine, including the high conversion (99.9%) and selectivity (97.9%) in mild reaction conditions, as well as the satisfactory stability in the recycling experiments. Compared to free enzyme, the as-obtained materials exhibited enhanced activity. Such results indicate that the hybrid materials are potentially good candidates in the industrial enzyme catalysis.

Charged Metalloporphyrin Polymers for Cooperative Synthesis of Cyclic Carbonates from CO2 under Ambient Conditions.

A facile and one-pot synthesis of metalloporphyrin-based ionic porous organic polymers (M-iPOPs) was performed through a typical Yamamoto-Ullmann coupling reaction for the first time. We used various characterization techniques to demonstrate that these strongly polar Al-based materials (Al-iPOP) possessed a relatively uniform microporosity, good swellable features, and a good CO2 capture capacity. If we consider the particular physicochemical properties, heterogeneous Al-iPOP, which bears both a metal active center and halogen anion, acted as a bifunctional catalyst for the solvent- and additive-free synthesis of cyclic carbonates from various epoxides and CO2 with an excellent activity and good recyclability under mild conditions. Interestingly, these CO2 -philic materials could catalyze the cycloaddition reaction smoothly by using simulated flue gas (15 % CO2 in N2 , v/v) as a raw material, which indicates that a stable local microenvironment and polymer swellability might promote the transformation. Thus, the introduction of polar ionic liquid units into metalloporphyrin-based porous materials is regarded as a promising new strategy for the chemical conversion of CO2 .

Metallosalen-Based Ionic Porous Polymers as Bifunctional Catalysts for the Conversion of CO2 into Valuable Chemicals.

A series of new metallosalen-based ionic porous organic polymers (POPs) were synthesized for the first time using a simple unique strategy based on the free-radical copolymerization reaction. Various techniques were used to characterize the physicochemical properties of these catalysts. These well-designed materials endowed high surface area, hierarchical porous structures, and enhanced CO2 /N2 adsorptive selectivity. Moreover, these POPs having both metal centers (Lewis acid) and ionic units (nucleophile) could serve as bifunctional catalysts in the catalytic conversion of CO2 into high value-added chemicals without any additional co-catalyst under mild and solvent-free conditions, for example, CO2 /epoxides cycloaddition and Nformylation of amines from CO2 and hydrosilanes. The results demonstrated that the irregular porous structure was very favorable for the diffusion of substrates and products, and the microporous structural property resulted in the enrichment of CO2 near the catalytic centers in the CO2 -involved transformations. Additionally, the superhydrophobic property could not only enhance the chemoselectivity of products but also promote the stability and recyclability of catalysts.

Cooperative Catalytic Activation of Si-H Bonds: CO2 -Based Synthesis of Formamides from Amines and Hydrosilanes under Mild Conditions.

A simple cooperative catalytic system was successfully developed for the solvent-free N-formylation of amines with CO2 and hydrosilanes under ambient conditions, which was composed of a Zn(salen) catalyst and quaternary ammonium salt. These commercially available binary components activated the Si-H bonds effectively, owing to the intermolecular synergistic effect between Lewis base and transition metal center (LB-TM), and subsequently facilitated the insertion of CO2 to form the active silyl formats, thereby leading to excellent catalytic performance at a low catalyst loading. Furthermore, the bifunctional Zn(salen) complexes, with two imidazolium-based ionic-liquid (IL) units at the 3,3'-position of salen ligand, acted as intramolecularly cooperative catalysts, and the solvent-regulated separation resulted in facile catalyst recycling and reuse.