Efficient and Sustainable in†situ Photo-Fenton Reaction to Remove Phenolic Pollutants by NH2 -MIL-101(Fe)/Ti3 C2 Tx Schottky-Heterojunctions.

Metal-organic frameworks (MOFs) with abundant active sites, a class of materials composed of metal nodes and organic ligands, is widely used for photocatalytic degradation of pollutants. However, the rapid recombination of photoinduced carriers of MOFs limits its photocatalytic degradation performance. Herein, Ti3 C2 Tx nanosheets-based NH2 -MIL-101(Fe) hybrids with Schottky-heterojunctions were fabricated by in situ hydrothermal assembly for improved photocatalytic activity. The photodegradation efficiencies of the NH2 -MIL-101(Fe)/Ti3 C2 Tx (N-M/T) hybrids for phenol and chlorophenol were 96.36 % and 99.83 % within 60 minutes, respectively. The N-M/T Schottky-heterojunction duly transferred electrons to the Ti3 C2 Tx nanosheets surface via built-in electric fields, effectively suppressing the recombination of photogenerated carriers, thereby improving the photocatalytic performance of NH2 -MIL-101(Fe). Moreover, the Fe-mixed-valence in the N-M/T led to improvement in the efficiency of the in situ generated photo-Fenton reactions, further enhancing the photocatalytic activity with more generated reactive oxygen species (ROS). The study proposes a highly effective removal of phenolic pollutants in wastewater.

Facile synthesis of porphyrin-MOFs with high photo-Fenton activity to efficiently degrade ciprofloxacin.

The slow conversion of Fe(Ⅱ)/Fe(III) cycle was largely limited the degradation efficiency of many photo-Fenton systems. Herein, four Fe-MOFs nanorods (namely Fe-TCPP-1, Fe-TCPP-2, Fe-TCPP-3, Fe-TCPP-4) with decreasing length-diameter ratios were synthesized in a household microwave oven, using photosensitizer porphyrin and iron ions with Fenton activity as building blocks. Among them, the Fe-TCPP-3 exhibited high photogenerated electron-hole (e--h+) separation efficiency and largest pore structure, endowing Fe-TCPP-3 with superior photo-Fenton property. In addition, Fe-TCPP-3 based photo-Fenton system was applied to efficiently degrade antibiotic ciprofloxacin (CIP) under neutral condition, due to the continuously generated reactive species (h+, e-, OH·, O2·-, 1O2) in Fe-TCPP-3 under visible-light irradiation. With irradiation for 30 min, the degradation efficiency of the system could reach about 73 %, which was about 26-fold towards the system without light irradiation. This study paved a way to modulating the photo-Fenton activity of MOF-based catalysts.

A catalyst-free co-reaction system of long-lasting and intensive chemiluminescence applied to the detection of alkaline phosphatase.

A catalyst-free co-reaction luminol-H2O2-K2S2O8 chemiluminescence (CL) system was developed, with long-life and high-intensity emission, and CL emission lasting for 6 h. A possible mechanism of persistent and intense emission in this CL system was discussed in the context of CL spectra, cyclic voltammetry, electron spin resonance (ESR), and the effects of radical scavengers on luminol-H2O2-K2S2O8 system. H2O2 and K2S2O8 co-reactants can promote each other to continuously generate corresponding radicals (OH•, 1O2, O2•-, SO4•-) that trigger the CL emission of luminol. H2O2 can also be constantly produced by the reaction of K2S2O8 and H2O to further extend the persistence of this CL system. CL emission can be quenched via ascorbic acid (AA), which can be generated through hydrolysis reaction of L-ascorbic acid 2-phosphate trisodium salt (AAP) and alkaline phosphatase (ALP). Next, a CL-based method was established for the detection of ALP with good linearity from 0.08 to 5 U·L-1 and a limit of detection of 0.049 U·L-1. The proposed method was used to detect ALP in human serum samples.

2D MOF-Based Photoelectrochemical Aptasensor for SARS-CoV-2 Spike Glycoprotein Detection.

A reliable and sensitive detection approach for SARS-CoV 2 is essential for timely infection diagnosis and transmission prevention. Here, a two-dimensional (2D) metal-organic framework (MOF)-based photoelectrochemical (PEC) aptasensor with high sensitivity and stability for SARS-CoV 2 spike glycoprotein (S protein) detection was developed. The PEC aptasensor was constructed by a plasmon-enhanced photoactive material (namely, Au NPs/Yb-TCPP) with a specific DNA aptamer against S protein. The Au NPs/Yb-TCPP fabricated by in situ growth of Au NPs on the surface of 2D Yb-TCPP nanosheets showed a high electron-hole (e-h) separation efficiency due to the enhancement effect of plasmon, resulting in excellent photoelectric performance. The modified DNA aptamer on the surface of Au NPs/Yb-TCPP can bind with S protein with high selectivity, thus decreasing the photocurrent of the system due to the high steric hindrance and low conductivity of the S protein. The established PEC aptasensor demonstrated a highly sensitive detection for S protein with a linear response range of 0.5-8 µg/mL with a detection limit of 72 ng/mL. This work presented a promising way for the detection of SARS-CoV 2, which may conduce to the impetus of clinic diagnostics.

An ultrathin 2D Yb(III) metal-organic frameworks with strong electrochemiluminescence as a "on-off-on" platform for detection of picric acid and berberine chloride form.

To investigate the strong electrochemiluminescence (ECL) of ultrathin two dimensional metal-organic frameworks (2D MOFs) is crucial. In this work, we reported the strong ECL behavior of 2D Yb-MOFs, which exhibited thickness-dependent ECL. The thinner the 2D Yb-MOFs, the stronger the ECL signals. The corresponding ECL emission mechanism was investigated in detail, which was ascribed to the thinner 2D Yb-MOF with larger specific surface area, provided more luminophores, better electronic conductivity and superior fluorescence quantum yield, which yielded a higher ECL intensity. Considering the excellent ECL performances above, the ultrathin 2D Yb-MOF-1 was selected as new ECL emitter so that a sensor could be fabricated to realize the "on-off-on" detection of picric acid (PA) and berberine chloride form (BCF). The proposed sensor strategy exhibited a good analytical performance, where the linear range for PA detection was from 0.1 µM to 1 µM with a limit of 81.3 nM, and that for BCF detection from 0.05 µM to 1 µM with a limit of 36.5 nM. This study carves out a novel avenue for exploiting excellent ECL materials.

Cu2+-modified MOF as laccase-mimicking material for colorimetric determination and discrimination of phenolic compounds with 4-aminoantipyrine.

Based on the laccase-mimicking activity of Cu2+-modified University of Oslo (UiO) metal-organic framework (UiO-67-Cu2+), we developed a colorimetric sensor array for distinguishing a series of phenols with different number and position of substituted hydroxyl group (-OH) and different substituent group on the benzene ring, including phenol, catechol, quinol, resorcinol, pyrogallol, phloroglucinol, o-chlorophenol, o-aminophenol, and o-nitrophenol. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of phenolic compounds were obtained by theoretical calculation. The results show that the lower the LUMO energy level, the easier the chromogenic reaction occurs. The UiO-67-Cu2+-catalyzed phenol chromogenic reaction showed a good linearity in the range from 0.1 to 200 µM with limit of detection approximately 61 nM. Through the detection of phenol in tap water and river water, the recovery rate and RSD (n = 3) were calculated as 94.1~103% and 1.0~3.3, respectively, showing good recovery, reliable results, and outstanding stability. Therefore, the proposed colorimetric sensor array will have a great potential for the detection of phenols in the environment. Schematic presentation of a simple and sensitive colorimetric strategy based on the laccase-mimicking activity of Cu2+-modified UiO-type metal-organic framework (MOFs, Uio-67-Cu2+) to distinguish phenols with analogous structures.

Cu vacancies enhanced photoelectrochemical activity of metal-organic gel-derived CuO for the detection of l-cysteine.

Defect engineering in the photoelectrochemical (PEC) process of photoelectrodes has been extensively studied. But insufficient attention has been received about the impact of metal vacancies (VM) in PEC process. Herein, the influence of Cu vacancies (VCu) on PEC performance of copper oxide (CuO) derived from Cu-based metal-organic gel (Cu-MOG) precursor was reported. It can be found that the presence of more VCu can improve the PEC activity of CuO photocathode by facilitating the charge separation and transfer. Moreover, the as-prepared CuO was presented as a new PEC sensor to detect l-cysteine (L-Cys) on the basis of the excellent PEC performance, which showed high sensitivity and selectivity. Good linear response of L-Cys within the range of 0.1-6 µM was performed with a detection limit of 0.04 µM. This work not only provides insights into the role of VM in the PEC process of photocathodes, but also proved the high potential applicability of CuO as a PEC device for biomolecule detection.

Controllable Synthesis of Porphyrin-Based 2D Lanthanide Metal-Organic Frameworks with Thickness- and Metal-Node-Dependent Photocatalytic Performance.

Synthesizing 2D metal-organic frameworks (2D MOFs) in high yields and rational tailoring of the properties in a predictable manner for specific applications is extremely challenging. Now, a series of porphyrin-based 2D lanthanide MOFs (Ln-TCPP, Ln=Ce, Sm, Eu, Tb, Yb, TCPP=tetrakis(4-carboxyphenyl) porphyrin) with different thickness were successfully prepared in a household microwave oven. The as-prepared 2D Ln-TCPP nanosheets showed thickness-dependent photocatalytic performances towards photooxidation of 1,5-dihydroxynaphthalene (1,5-DHN) to synthesize juglone. Particularly, the Yb-TCPP displayed outstanding photodynamic activity to generate O2 - and 1 O2 . This work not only provides fundamental insights into structure designing and property tailoring of 2D MOFs nanosheets, but also pave a new way to improve the photocatalytic performance.

One-step synthesis of Cu(II) metal-organic gel as recyclable material for rapid, efficient and size selective cationic dyes adsorption.

Efficient removal of non-biodegradable and hazardous dyes from wastewater remains a hot research topic. Herein, a rationally designed a Cu(II)-based metal-organic gel (Cu-MOG) with a nanoporous 3D network structure prepared via a simple one-step mixing method was successfully employed for the removal of cationic dyes. The Cu-MOG exhibited high efficiency, with an adsorption capacity of up to 650.32 mg/g, and rapid adsorption efficiency, with the ability to adsorb 80% of Neutral Red within 1 min. The high adsorption efficiency was attributed to its large specific surface area, which enabled it to massively bind cationic dyes through electrostatic interaction, and a nanoporous structure that promoted intra-pore diffusion. Remarkably, the Cu-MOG displayed size-selective adsorption, based on adsorption studies concerning dyes of different sizes as calculated by density functional theory. Additionally, the adsorption performance of the Cu-MOG still maintained removal efficiency of 100% after three regeneration cycles. These results suggested that the Cu-MOG could be expected to be a promising and competitive candidate to conveniently process wastewater.

CuO nanoparticles derived from metal-organic gel with excellent electrocatalytic and peroxidase-mimicking activities for glucose and cholesterol detection.

A simple and efficient strategy was developed to fabricate CuO nanoparticles (CuO-NPs) with high surface area by the direct pyrolysis of a metal-organic gel (MOG) precursor for constructing versatile catalytic interfaces. Unexpectedly, the obtained CuO-NPs exhibited excellent electrocatalytic activity for glucose (Glu) oxidation reaction. The linear range of glucose was from 5 µM to 600 with the detection limit of 0.59 µM. Additionally, the CuO-NPs showed distinguished intrinsic peroxidase-mimicking activities, which can be further used as biomimetic nanozymes for sensitively and rapidly detecting cholesterol. A good linearity of cholesterol was performed in the range from 1 µM to 15 µM with the detection limit of 0.43 µM. The as-prepared CuO-NPs could provide a versatile catalytic platform for the application of electrochemical sensors and biomimetic enzyme catalytic systems. This study proved the high potential of MOG-derived nanostructured transition metal oxides (TMOs) with multiple complex functions.

A copper(II)/cobalt(II) organic gel with enhanced peroxidase-like activity for fluorometric determination of hydrogen peroxide and glucose.

A bimetallic organic gel was prepared by mixing the bridging ligand 2,4,6-tri(4-carboxyphenyl)-1,3,5-triazine with Cu(II) and Co(II) ions at room temperature. The resulting metal-organic gel (MOG) shows enhanced peroxidase-like activity, most likely due to the synergetic redox cycling between Co(III)/Co(II) and Cu(II)/Cu(I) pairs. These accelerate interfacial electron transfer and generation of hydroxy radicals. The MOG can catalyze the reaction of H2O2 with terephthalic acid (TPA), producing a blue fluorescence product with the maximum excitation/emission at 315/446 nm. The enzyme mimic was used to design a fluorometric method for H2O2 that has a 81 nM detection limit. H2O2 is also formed by glucose oxidase-assisted oxidation of glucose by oxygen, and an assay for glucose was worked out based on the above method. It has a 0.33 µM detection limit. This study may open up a new avenue to design and synthesize nanomaterial-based biomimetic catalysts with multiple metal synergistically enhanced catalytic activity for potential applications in biocatalysis, bioassays and nano-biomedicine. Graphical abstracts Schematic presentation of the synergic catalytic effect of Cu(II)/Co(II) bimetallic organic gel promoted by the redox cycle between Co(III)/Co(II) and Cu(II)/Cu(I) pairs. The bimetallic organic gel can catalyze the reaction of H2O2 with terephthalic acid, thereby producing a blue-fluorescent product.

Terbium(III) Organic Gels: Novel Antenna Effect-Induced Enhanced Electrochemiluminescence Emitters.

Metal organic gels (MOGs) have emerged as a new class of smart soft materials with superb luminescence properties and have attracted tremendous attention in various aspects. However, the electrochemiluminescence (ECL) behavior of MOGs has not been reported yet. In this work, cathode electrochemiluminescence (ECL) emission of terbium(III) organic gels (TOGs) was reported for the first time with potassium persulfate (K2S2O8) as an efficient coreactant. TOGs were synthesized by a facile one-step strategy, mixing terbium ions (Tb3+) and the ligand 4'-(4-carboxyphenyl)-2,2':6',2''-terpyridine (Hcptpy) at room temperature. The possible strong green ECL emission mechanism was discussed in detail and ascribed to the external coreactant enhancement and internal antenna effect enhancement. Moreover, the promising application of TOGs in analytical chemistry was clarified by the ECL on-off detection of tetracycline. This remarkable discovery of ECL emission of TOGs may pioneer the application of MOGs in ECL fields.

In Situ Synthesis of Gold Nanoparticles/Metal-Organic Gels Hybrids with Excellent Peroxidase-Like Activity for Sensitive Chemiluminescence Detection of Organophosphorus Pesticides.

Until now, despite much progress in the study of metal-organic gels (MOGs), the modification of transition-metal containing MOGs with noble metal nanoparticles (NPs) is far from fully developed. Herein, iron-based MOGs nanosheet hybrids with gold NPs (AuNPs) immobilization were first synthesized by a facile in situ grown strategy at ambient conditions. It is found that the as-prepared AuNPs/MOGs (Fe) hybrids exhibited enhanced mimicking peroxidase-like activity, making them endowed with outstanding performance in chemiluminescence (CL) field in the presence of H2O2. The remarkable CL enhancement by AuNPs/MOGs (Fe) hybrids was attributed to the modification of AuNPs on MOGs (Fe) nanosheets, which could synergistically accelerate the CL reaction by speeding up the generation of OH•, O2•-, and 1O2. Accordingly, a sensitive CL detection of organophosphorus pesticides was successfully achieved by the AuNPs/MOGs (Fe) hybrids CL enhancing system in the range of 5-800 nM with a detection limit of 1 nM. We envision that this highly active and novel enzyme mimetic catalyst can be applicable to other extended AuNPs/MOGs (Fe) hybrid-based CL systems for sensitive detection of various analytes.

Genome-Wide Screening for Novel Candidate Virulence Related Response Regulator Genes in Xanthomonas oryzae pv. oryzicola.

Two-component regulatory system (TCS), a major type of cellular signal transduction system, is widely used by bacteria to adapt to different conditions and to colonize certain ecological niches in response to environmental stimuli. TCSs are of distinct functional diversity, genetic diversity, and species specificity (pathovar specificity, even strain specificity) across bacterial groups. Although TCSs have been demonstrated to be crucial to the virulence of Xanthomonas, only a few researches have been reported about the studies of TCSs in Xanthomonas oryzae pathovar oryzicola (hereafter Xoc), the pathogen of rice bacterial streak disease. In the genome of Xoc strain GX01, it has been annotated 110 TCSs genes encoding 54 response regulators (RRs), 36 orthodox histidine kinase (HKs) and 20 hybrid histidine kinase (HyHKs). To evaluate the involvement of TCSs in the stress adaptation and virulence of Xoc, we mutated 50 annotated RR genes in Xoc GX01 by homologous vector integration mutagenesis and assessed their phenotypes in given conditions and tested their virulence on host rice. 17 RR genes were identified to be likely involved in virulence of Xoc, of which 10 RR genes are novel virulence genes in Xanthomonas, including three novel virulence genes for bacteria. Of the novel candidate virulence genes, some of which may be involved in the general stress adaptation, exopolysaccharide production, extracellular protease secretion and swarming motility of Xoc. Our results will facilitate further studies on revealing the biological functions of TCS genes in this phytopathogenic bacterium.

Novel Iron(III)-Based Metal-Organic Gels with Superior Catalytic Performance toward Luminol Chemiluminescence.

Novel metal-organic gels (MOGs) consisting of iron (Fe3+) as the central ion and 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) as the ligand were synthesized by a mild facile strategy. The Fe(III)-containing metal-organic xerogels (Fe-MOXs), obtained after removing the solvents in MOGs, were found to exhibit outstanding performance in the catalysis of luminol chemiluminescence (CL) for the first time even in the absence of extra oxidants such as hydrogen peroxide. The possible CL mechanism was discussed according to the electro/optical measurements, including electron paramagnetic resonance (EPR), UV-vis absorption, and CL spectra, as well as the effects of radical scavengers on Fe-MOXs-catalyzed luminol CL system, suggesting that the CL emission of luminol might originate from the intrinsic oxidase-like catalytic activity of Fe-MOXs on the decomposition of dissolved oxygen. Additionally, the potential practical application of the resulting luminol-Fe-MOXs system was evaluated by the quantitative analysis of dopamine. Good linearity over the range from 0.05 to 0.6 µM was obtained with the limit of detection (LOD, 3σ) of 20.4 nM and acceptable recoveries ranging from 98.6 to 105.4% in human urine. These results may open up the promising application of novel metal-organic gels as highly effective catalysts in the field of chemiluminescence.

Al-based metal-organic gels for selective fluorescence recognition of hydroxyl nitro aromatic compounds.

The novel class of luminescent Al3+-based metal-organic gels (Al-MOGs) have been developed by mix 4-[2,2':6',2″-terpyridine]-4'-ylbenzoic acid (Hcptpy) with Al3+ under mild condition. The as-prepared Al-MOGs have not only multiple stimuli-responsive properties, but selective recognition of hydroxyl nitro aromatic compounds, which can quench the fluorescence of the Al-MOGs, while other nitro aromatic analogues without hydroxyl substitutes cannot. The fluorescence of Al-MOGs at 467nm was seriously quenched by picric acid (PA) whose lowest unoccupied molecular orbital (LUMO) energy levels are lower than those of three other hydroxyl nitro aromatic compounds including 4-nitrophenol (4-NP), 3,5-dinitrosalicylic acid (3,5-DNTSA) and 2,4-dinitrophenol (2,4-DNP). Thus, PA was chosen as a model compound under optimal conditions and the relative fluorescence intensity of Al-MOGs was proportional to the concentration of PA in the range of 5.0-320.0µM with a detection limit of 4.64µM. Furthermore, the fluorescence quenching mechanism has also been investigated and revealed that the quenching was attributed to inner filter effects (IFEs), as well as electron transfer (ET) between Al-MOGs and PA.

SIRT1 regulates lipopolysaccharide-induced CD40 expression in renal medullary collecting duct cells by suppressing the TLR4-NF-κB signaling pathway.

AIMS: Recent evidence indicates that sirtuin1 (SIRT1), an NAD+-dependent deacetylase, exerts a protective effect against inflammatory kidney injury by suppressing pro-inflammatory cytokines production. The co-stimulatory molecule, CD40, is expressed in a variety of inflammatory diseases in the kidney. Here, we aimed to investigate the potential effect of SIRT1 on CD40 expression induced by lipopolysaccharide (LPS) and to disclose the underlying mechanisms in renal inner medullary collecting duct (IMCD) cells. MAIN METHODS: mRNA and protein expressions were identified by quantitative real-time PCR and Western blot respectively. Subcellular localization of SIRT1 and CD40 were respectively detected by immunofluorescence and immunohistochemical staining. Small-interfering RNA (siRNA) was carried out for mechanism study. KEY FINDINGS: LPS reduced SIRT1 expression and up-regulated the expression of CD40, Toll-like receptor 4 (TLR4) and phospho-NF-κBp65 (p-NF-κBp65) in time- and concentration-dependent manners. Moreover, SIRT1 overexpression or activation by SRT1720 diminished the expression of CD40, TLR4 and p-NF-κBp65, which was reversed by SIRT1 siRNA or inhibitors Ex527 and sirtinol in LPS-stimulated IMCD cells. In addition, knockdown of TLR4 decreased the expression of CD40 and p-NF-κBp65 in IMCD cells exposed to LPS. Knockdown of NF-κBp65 or NF-κBp65 inhibition by pyrrolidine dithiocarbamate (PDTC) reduced LPS-induced CD40 expression in IMCD cells. Importantly, the inhibitory effect of SIRT1 on the expression of CD40 and p-NF-κBp65 was augmented by pre-treating with TLR4 siRNA. SIGNIFICANCE: Our data indicate that SIRT1 inhibits LPS-induced CD40 expression in IMCD cells by suppressing the TLR4-NF-κB signaling pathway, which might provide novel insight into understanding the protective effect of SIRT1 in kidney.

[Maintenance and complications of hemodialysis equipment].

Through the hemodialysis machine and water treatment systems maintenance, the result of complications caused by dialysis can be eliminated. It also of extended the life of hemodialysis machines and improve the quality of dialysis.