A portable europium complex-loaded fluorescent test paper combined with smartphone analysis for the on-site and visual detection of mancozeb in food samples.

The on-site detection of mancozeb in food samples holds immense value for food safety. A red-fluorescent europium complex (Eu-PYDC-Phen) has been prepared and employed as a fluorescence probe for mancozeb detection. The optimized probe suspension exhibits excellent detection performances, including a wide linear range (0-0.24 mM), low detection limit (65 nM), rapid response (2 mins) and high selectivity. Moreover, a portable detection platform was carefully designed, integrating the Eu-PYDC-Phen-based fluorescent test strips with smartphone color recognition software. This innovative platform enables visual and on-site detection of mancozeb in tomato, apple, and lettuce, achieving satisfactory recovery rates (90.34 to 106.50%). Furthermore, the integration of machine learning techniques based on hierarchical clustering algorithm has the potential to further improve the prediction and decision-making efficiency in mancozeb detection. This work provides an economical, convenient, and reliable strategy for on-site detection of pesticide in agricultural products, thereby making a meaningful contribution to food safety.

A portable Eu-MOF-loaded paper-based probe integrated with smartphone for the visual and on-site detection of Cr2O72- in aqueous media.

The high toxicity of dichromate anion (Cr2O72-) its accurate necessitates its sensitive and effective detection to safeguard human health. The study introduces a Eu-MOF fluorescent probe, named as Eu-TDCA, synthesized using 2,5-thiophenedicarboxylic acid (H2TDCA) as a bridging ligand for the detection of Cr2O72- in aqueous media. The probe suspension can detect Cr2O72- through fluorescence quenching, and the detection process exhibits a wide linear range (0-85 and 85-230 mg/L), low limit of detection (LOD, 5.1 µg/L) and rapid response speed (2 min). Furthermore, a portable Eu-TDCA-loaded paper-based probe, integrated with a smartphone color recognition app, was developed for the visual, sensitive and quantitative detection of Cr2O72- in real lake and river water samples, achieving satisfactory recoveries of 99.72%-103.75 %. Additionally, an advanced logic gate device was designed to simplify the detection process, providing a new direction for intelligent on-line detection of analytes.

A smartphone-integrated test paper sensing platform for visual and intelligent detection of nitrofurantoin in honey samples.

The development of a rapid and convenient detection method for nitrofurantoin (NFT) residual is of great significance for food safety. Herein, a new fluorescent probe (Eu-TDCA-Phen) was developed for the visual and sensitive assay of NFT through the fluorescence quenching effect of inner filter effect (IFE) and photo-induced electron transfer (PET). The probe suspension demonstrates a wide linear range (0-0.16 mM), low detection limit (90 nM), high sensitivity, and rapid response time (2 min) in the "turn-off" process. To quantify the visual detection process, a smartphone-assisted test paper sensing platform was established and was applied for NFT determination in real honey samples, achieving satisfactory recovery rate ranges from 98.04 % to 105.04 %. Furthermore, a logic gate device was integrated with the sensing platform to streamline the visual detection process. The sensing platform offers several merits, including simpleness, quantification, portability and cost-effectiveness, making it highly suitable for real-time and on-site detection of antibiotics in food samples.

Electrospun silk fibroin/fibrin vascular scaffold with superior mechanical properties and biocompatibility for applications in tissue engineering.

Electrospun scaffolds play important roles in the fields of regenerative medicine and vascular tissue engineering. The aim of the research described here was to develop a vascular scaffold that mimics the structural and functional properties of natural vascular scaffolding. The mechanical properties of artificial vascular tissue represent a key issue for successful transplantation in small diameter engineering blood vessels. We blended silk fibroin (SF) and fibrin to fabricate a composite scaffold using electrospinning to overcome the shortcomings of fibrin with respect to its mechanical properties. Subsequently, we then carefully investigated the morphological, mechanical properties, hydrophilicity, hemocompatibility, degradation, cytocompatibility and biocompatibility of the SF/fibrin (0:100), SF/fibrin (15:85), SF/fibrin (25:75), and SF/fibrin (35:65) scaffolds. Based on these in vitro results, we implanted SF/fibrin (25:75) vascular scaffold subcutaneously and analyzed its in vivo degradation and histocompatibility. The fiber structure of the SF/fibrin hybrid scaffold was smooth and uniform, and its fiber diameters were relatively small. Compared with the fibrin scaffold, the SF/fibrin scaffold clearly displayed increased mechanical strength, but the hydrophilicity weakened correspondingly. All of the SF/fibrin scaffolds showed excellent blood compatibility and appropriate biodegradation rates. The SF/fibrin (25:75) scaffold increased the proliferation and adhesion of MSCs. The results of animal experiments confirmed that the degradation of the SF/fibrin (25:75) scaffold was faster than that of the SF scaffold and effectively promoted tissue regeneration and cell infiltration. All in all, the SF/fibrin (25:75) electrospun scaffold displayed balanced and controllable biomechanical properties, degradability, and good cell compatibility. Thus, this scaffold proved to be an ideal candidate material for artificial blood vessels.

Smartphone-integrated paper-based sensing platform for the visualization and quantitative detection of pymetrozine.

Pymetrozine (PYM) is an effective pyridine insecticide for controlling aphids, while its residues pose a serious threat to human health. Herein, a europium complex (Eu-DBPA, DBPA represents deprotonated 2,5-dibromoterephthalic acid ligand) probe was prepared for the detection of PYM via fluorescence quenching. The detection process has the advantages of short response time (2 min), wide linear range (0-4 and 4-45 mg/kg) and low detection limit (2.2 µg/kg). Furthermore, a portable detection platform was designed by integrating Eu-DBPA-based paper strip with smartphone and applied for the visual detection of PYM in real cucumber, tomato, cabbage and apple samples, obtaining satisfactory recovery (99.00 %-107.00 %) and low standard deviation (RSD < 3.4 %). In addition, a logic gate device was designed to simplify the detection process. The smartphone-integrated paper-based probe detection platform provides a new strategy for intelligent and online identification of hazards in environmental and biological samples.

An intelligent smartphone-test strip detection platform for rapid and on-site sensing of benzoyl peroxide in flour samples.

Benzoyl peroxide (BPO) is a commonly used flour whitener, but its excessive usage can have adverse effects on human health, such as nutrient loss, vitamin deficiencies and certain diseases. In this study, a europium metal organic framework (Eu-MOF) fluorescence probe was prepared, which exhibited a strong fluorescence emission at 614 nm upon excitation at 320 nm, with a high quantum yield of 8.11%. The red fluorescence of the probe could be effectively quenched by BPO through the inner filter effect (IFE) and photoinduced electron transfer (PET) mechanism. The detection process offered several advantages, including a wide linear range of 0-0.95 mM, a low detection limit of 66 nM and a fast fluorescence response of 2 min. Furthermore, an intelligent detection platform was designed to enhance the practical application of the detection method. This platform combined the portability and visuality of a traditional test strip with the color recognition capability of a smartphone, allowing for the visualization and quantitative detection of BPO in a convenient and user-friendly manner. The detection platform was successfully applied to the analysis of BPO in real flour samples with satisfactory recoveries (99.79%-103.94%), suggesting a promising strategy for the rapid and on-site detection of BPO in food samples.

A smartphone-assisted paper-based ratio fluorescent probe for the rapid and on-site detection of tetracycline in food samples.

Rapid, sensitive and portable analytical methods for on-site detection of tetracycline (TC) in food samples is of critical importance for food safety and public health. In this study, a dual-emission ratio fluorescent probe (Gd0.9@Eu0.1) was prepared and utilized for the detection of tetracycline (TC) by observing the fluorescence color change from blue to red. The detection process exhibits a wide linear range (0-52.0 µM), good selectivity and low detection limit (14 nM). A paper-based probe and a colorimetric card was constructed for the visual detection of TC. Furthermore, a novel and portable detection platform combining smartphone and test strip was exploited for the quantitative and on-site detection of TC in real pork sample. The developed method was validated through intra- (n = 5) and inter-day (n = 2) measurements, as well as comparison with a traditional HPLC method. These statistical result validate the reliability and accuracy of the developed method. This intelligent detection platform represents a promising approach for the rapid, sensitive and visual detection of TC in food samples.

MicroRNAs involved in the trans-kingdom gene regulation in the interaction of maize kernels and Fusarium verticillioides.

Maize ear rot is a widespread disease and the main pathogen is Fusarium verticillioides. Plant microRNAs (miRNAs) have great effects on disease resistance and it has been reported that maize miRNA participates in defense responses in maize ear rot. However, the trans-kingdom regulation of miRNAs between maize and F. verticillioides remains uncharacterized. In this study, the relationship between miRNA-like RNAs (milRNAs) of F. verticillioides and pathogenicity was investigated, followed by sRNA analysis and degradome sequencing of miRNA profiles and the target genes of maize and F. verticillioides after inoculation. It was found that the milRNA biogenesis positively regulated the pathogenicity of F. verticillioides by knocking out the gene FvDicer2-encoded Dicer-like protein in F. verticillioides. Following inoculation with F. verticillioides, 284 known and 6571 novel miRNAs were obtained in maize, including 28 miRNAs differentially expressed at multiple time points. The target genes of maize differentially expressed miRNAs in F. verticillioides mediated multiple pathways, including autophagy and MAPK signaling pathway. Fifty-one novel F. verticillioides milRNAs were predicted to target 333 genes in maize involved in MAPK signaling pathways, plant hormone signaling transduction and plant-pathogen interaction pathways. Additionally, the miR528b-5p in maize targeted the mRNA of FvTTP which encoded a twice transmembrane protein in F. verticillioides. The FvTTP-knockout mutants displayed decreased pathogenicity and reduced synthesis of fumonisins. Thus, by interfering with the translation of FvTTP, the miR528b-5p inhibited F. verticillioides infection. These findings suggested a novel function of miR528 in resisting F. verticillioides infection. The miRNAs identified in this research and their putative target genes can be used to further elucidate the trans-kingdom functions of microRNAs in plant pathogen interaction.

Quercetin prevents the ferroptosis of OPCs by inhibiting the Id2/transferrin pathway.

Spinal cord injury (SCI) is a destructive neurological disorder that causes impaired mobility, sensory, and autonomic dysfunctions. The loss of oligodendrocyte progenitor cells (OPCs), which can differentiate into mature oligodendrocytes and re-myelinate damaged axons, is related to poorer recovery for SCI patients. However, inhibiting OPCs loss has always been a difficult problem to overcome. In this study, we demonstrated the anti-ferroptosis effects of quercetin as a mechanism in erastin-induced OPC ferroptosis. Quercetin ameliorated erastin-induced ferroptosis in OPCs, as indicated by decreased iron concentration, reactive oxygen species (ROS) production, and increased content of glutathione (GSH) as well as more normal mitochondria morphology. Compared with erastin-induced OPCs, the myelin basic protein (MBP)-positive myelin and NF200-positive axonal was remarkably increased in quercetin-treated OPCs. Furthermore, quercetin ameliorated the erastin-induced ferroptosis as well as the myelin and axon loss of OPCs by downregulating transferrin. Transfected OPCs with transferrin overexpression plasmids significantly abrogated the protective role of quercetin in OPC ferroptosis. Using ChIP-qPCR, a direct interaction of transferrin with its upstream gene Id2 was found. The overexpression of Id2 reversed the effect of quercetin on OPC ferroptosis. In vivo study found that quercetin greatly decreased the area of injury, and enhanced the BBB score after SCI. Furthermore, in the SCI model, quercetin significantly downregulated Id2 and transferrin expression, while significantly up-regulated GPX4 and PTGS2 expression. In conclusion, quercetin prevents the ferroptosis of OPCs by inhibiting the Id2/transferrin pathway. These findings highlight quercetin as an anti-ferroptosis agent for the treatment or prevention of spinal cord injury.

A highly selective and sensitive europium-organic framework sensor for the fluorescence detection of fipronil in tea.

A europium-based metal organic framework (Eu-TFPA-MOF) was used for the fluorescence detection of fipronil in green tea and oolong tea for the first time. The red fluorescence of Eu-TFPA-MOF could be quenched significantly by low concentration (0.24 mM) of fipronil, and the "turn off" process exhibited quick response time (2 min), high sensitivity and selectivity, low detection limits (4.4 nM) and wide linear range (0-0.15 mM). The mechanism of fluorescence quenching was mainly attributed to static quenching process and the competitive absorption of excitation energy. Besides, the spiked and recovery test indicated that Eu-TFPA-MOF could be used in the fluorescence detection of fipronil in real green tea and oolong tea sample and the process had the advantages of simple pretreatment and satisfactory recoveries (98.33-106.17 %). More importantly, a simple, portable and low-cost smartphone-assisted test strip were designed for the visual detection of fipronil in real tea samples. The detection platform will be beneficial for tea quality safety and human heath, and is expected to be applied in other agricultural product safety field.

High-resolution mapping reveals a Ht3-like locus against northern corn leaf blight.

Northern corn leaf blight (NCLB), caused by the fungal pathogen Exserohilum turcicum, poses a grave threat to maize production worldwide. The resistance gene in A619Ht3, discovered decades ago, is an important genetic resource for NCLB control. By using a pair of near-isogenic lines (NILs) A619Ht3 and A619, together with the resistant and susceptible bulks derived from the cross of A619Ht3 and L3162 lines, we initially detected a Ht3-like (Ht3L) locus in bin 8.06 that was closely associated with NCLB resistance. We then performed five rounds of fine-mapping, which ultimately delimited the Ht3L locus to a 577-kb interval flanked by SNP markers KA002081 and KA002084. Plants homozygous for the Ht3L/Ht3L genotype exhibited an average reduction in diseased leaf area (DLA) by 16.5% compared to plants lacking Ht3L locus. The Ht3L locus showed extensive variation in genomic architecture among different maize lines and did not appear to contain any genes encoding canonical cell wall-associated kinases against NCLB. Moreover, the Ht3L locus was located ∼2.7 Mb away from the known Htn1 locus. We speculate that the Ht3L locus may contain a bona fide Ht3 gene or a novel NCLB resistance gene closely linked to Ht3. In practice, the Ht3L locus is a valuable resource for improving maize resistance to NCLB.

Stubby or Slender? Ear Architecture Is Related to Drought Resistance in Maize.

Ear architecture is determined by two stable heritable traits, kernel row number (KRN) and kernel number per row (KNPR), but its relationship with drought resistance is still vague. To this end, we obtained 16 and 11 hybrids with slender (less KRN but more KNPR) and stubby (more KRN but less KNPR) ears by intentionally crossbreeding, respectively. These hybrids were exposed to a seven-day water deficit (WD) since silk emergence coupled with synchronous (SP) and continuous pollination (CP) to alter the pollination time gaps on ears. The results showed that the emerged silks in CP were 9.1 and 9.0% less than in the SP treatment in the stubby and slender ears, respectively, suggesting the suppression of asynchronous pollination on silk emergence. The stubby ears performed higher silking rate and yield compared with the slender ears with or without drought stress. To eliminate the inherent difference in sink capacities, we selected four hybrids for each ear type with similar silk and kernel numbers for further analyses. Interestingly, the stubby ears were less affected in silking rate and thus performed higher yield under drought compared with the slender ears. The finding suggests that ear architecture matters in the determination of drought resistance that deserves more attention in breeding.

Regulating the Li Nucleation/Growth Behavior via Cu2O Nanowire Array and Artificial Solid Electrolyte Interphase toward Highly Stable Li Metal Anode.

Lithium (Li) metal has been considered to be the most promising anode material for next-generation rechargeable batteries. Unfortunately, the hazards induced by dendrite growth and volume fluctuation hinder its commercialized application. Here, a three-dimensional (3D) current collector composed of a vertically aligned Cu2O nanowire that is tightly coated with a polydopamine protective layer is developed to solve the encountered issues of lithium metal batteries (LMBs). The Cu2O nanowire arrays (Cu2O NWAs) provide abundant lithiophilic sites for inducing Li nucleation selectively to form a thin Li layer around the nanowires and direct subsequent Li deposition. The well-defined nanochannel works well in confining the Li growth spatially and buffering the volume change during the repeated cycling. The PDA coatings adhered onto the outline of the Cu2O NWAs serve as the artificial solid electrolyte interface to isolate the electrode and electrolyte and retain the interfacial stability. Moreover, the increased specific area of copper foam (CF) can dissipate the local current density and further suppress the growth of Li dendrites. As a result, CF@Cu2O NWAs@PDA realizes a dendrite-free morphology and the assembled symmetrical batteries can work stably for over 1000 h at 3 mA cm-2. When CF@Cu2O NWAs@PDA is coupled with a LiFePO4 cathode, the full cells exhibit improved cycle stability and rate performance.

Two Co(II)/Ni(II) complexes based on nitrogenous heterocyclic ligands as high-performance electrocatalysts for the hydrogen evolution reaction.

Two transition metal complexes {[Co2(bpda)4(H2O)2]·4H2O}n(Co-1) and {[Ni(bpda)2(H2O)2]·2H2O}(Ni-2) (H2bpda = 2,2'-bipyridine-4,4'-dicarboxylic acid) have been synthesized by a hydrothermal method and characterized. These two compounds can be explored as stable electrocatalysts in the hydrogen evolution reaction (HER) using two important parameters: the overpotential and Tafel slope (TS). Electrochemical studies suggest that the reaction kinetics of a Co-1 catalyst is more favorable than that of a Ni-2 catalyst. Co-1 exhibits better HER performance with an overpotential of 182 mV at a current density of 10 mA cm-2, a small TS of 87.21 mV dec-1 and superior long-term durability (of up to 3000 cycles). Structural analysis shows that its catalytic activity is improved due to the two mixed valence cobalt ions and the pore structure formed by hydrogen bonds in Co-1, which is different from that of Ni-2. In addition, the mechanism of the HER is also explained theoretically by DFT molecular orbital and free energy calculations in this article.

A turn-off Eu-MOF@Fe2+ sensor for the selective and sensitive fluorescence detection of bromate in wheat flour.

A new europium metal-organic framework (Eu-MOF) was prepared by simple hydrothermal method. The product exhibited intense red fluorescence, long fluorescence lifetime (0.454 ms) and excellent fluorescence stability. The fluorescence titration result showed that Fe3+ could completely quench the fluorescence of Eu-MOF, while the fluorescence quenching effect of Fe2+ or bromate was negligible. Considering the strong oxidizing property of bromate, a "turn off" Eu-MOF@Fe2+ sensor toward bromate was designed by generating Fe3+ due to the redox reaction. The results showed that the sensor displayed a wide linear range (0-0.2 mM), high sensitivity (LOD = 3.7 × 10-6 mol/L), good selectivity and resistant to possible interferences in real four sample. Furthermore, the detection mechanism was investigated by PXRD, XPS and UV-Vis methods. More importantly, the Eu-MOF@Fe2+ sensor was further applied to detect bromate in wheat flour with satisfactory recovery (95.30%-104.38%) and accuracy (RSD < 2.85%). These results suggest that Eu-MOF@Fe2+ can be used as a potential sensor to detect bromate in food industry.

Covalent Organic Framework with Highly Accessible Carbonyls and π-Cation Effect for Advanced Potassium-Ion Batteries.

Covalent organic frameworks (COF) possess a robust and porous crystalline structure, making them an appealing candidate for energy storage. Herein, we report an exfoliated polyimide COF composite (P-COF@SWCNT) prepared by an in situ condensation of anhydride and amine on the single-walled carbon nanotubes as advanced anode for potassium-ion batteries (PIBs). Numerous active sites exposed on the exfoliated frameworks and the various open pathways promote the highly efficient ion diffusion in the P-COF@SWCNT while preventing irreversible dissolution in the electrolyte. During the charging/discharging process, K+ is engaged in the carbonyls of imide group and naphthalene rings through the enolization and π-K+ effect, which is demonstrated by the DFT calculation and XPS, ex-situ FTIR, Raman. As a result, the prepared P-COF@SWCNT anode enables an incredibly high reversible specific capacity of 438 mA h g-1 at 0.05 A g-1 and extended stability. The structural advantage of P-COF@SWCNT enables more insights into the design and versatility of COF as an electrode.

Neuroprotective effects of four different fluids on cerebral ischaemia/reperfusion injury in rats through stabilization of the blood-brain barrier.

Protecting the blood-brain barrier (BBB) is a potential strategy to treat cerebral ischaemic injury. We previously reported that hypertonic sodium chloride hydroxyethyl starch 40 (HSH) treatment alleviates brain injury induced by transient middle cerebral artery occlusion (tMCAO). However, other fluids, including 20% mannitol (MN), 3% hypertonic sodium chloride (HTS) and hydroxyethyl starch 130/0.4 solution (HES), have the same effect as HSH in cerebral ischaemia/reperfusion injury (CI/RI) remains unclear. The present study evaluated the protective effects of these four fluids on the BBB in tMCAO rats. Sprague-Dawley (SD) rats were randomly assigned to six groups. A CI/RI rat model was established by tMCAO for 120 min followed by 24 h of reperfusion. The sham and tMCAO groups were treated with normal saline (NS), whereas the other four groups were treated with the four fluids. After 24 h of reperfusion, neurological function, brain oedema, brain infarction volume, permeability of the BBB, cortical neuron loss and protein and mRNA expression were assessed. The four fluids (especially HSH) alleviated neurological deficits and decreased the infarction volume, brain oedema, BBB permeability and cortical neuron loss induced by tMCAO. The expression levels of GFAP, IL-1ß, TNF-α, MMP-9, MMP-3, AQP4, MMP-9, PDGFR-ß and RGS5 were decreased, whereas the expression levels of laminin and claudin-5 were increased. These data suggested that small-volume reperfusion using HSH, HES, MN and HTS ameliorated CI/RI, probably by attenuating BBB disruption and postischaemic inflammation, with HSH exerting the strongest neuroprotective effect.

Multi-functional lanthanide-CPs based on tricarboxylphenyl terpyridyl ligand as ratiometric luminescent thermometer and highly sensitive ion sensor with turn on/off effect.

A series of isostructural lanthanide coordination polymers (Ln-CPs) formulated as [Ln(tcptpy)(H2O)2·2H2O]n {Ln3+ = Sm3+ (1), Eu3+ (2), Gd3+ (3), Tb3+ (4), Dy3+ (5); H3tcptpy = 4-(2,4,6-tricarboxylphenyl)-4,2':6',4''-terpyridine} has been afforded and characterized systematically. Their structures were established by single-crystal X-ray diffraction. All the complexes feature two dimensional (2D) layers with (4,4)-connected topology. By virtue of the isostructural frameworks, a family of binary co-doped Ln-CPs [Tb1-xEuxtcptpy]n was achieved for ratiometric temperature sensors, among which Tb0.897Eu0.103tcptpy exhibits a good linear response to the temperature range from 305-340 K, with a maximum relative sensitivity (Sm) of 8.41% K-1 at 340 K. Moreover, Tb-CPs exhibit excellent applications as luminescent sensors for the detection of nitrobenzene and Fe3+ cations with high selectivity and sensitivity based on a luminescence quenching approach. The possible mechanisms of the fluorescence quenching effect were also investigated.

Lanthanide complexes based on a conjugated pyridine carboxylate ligand: structures, luminescence and magnetic properties.

Three lanthanide compounds have been synthesized, namely, {[Dy2(bpda)3(H2O)3]4·2H2O}(Dy-1), {[Sm(bpda)2·(H2O)]·H2O} n (Sm-2) and {[Tb2(bpda)3(H2O)3]4·2H2O} (Tb-3) (H2bpda = 2,2'-bipyridine-6,6'-dicarboxylic acid). Their structures were determined by single crystal X-ray diffraction and characterized by elemental analysis, infrared spectroscopy and thermogravimetric analysis. Dy-1 and Tb-3 are isostructural with a conjugate bimolecular four-nuclear cluster structure constructed with intramolecular hydrogen bonds and they form a 3D supramolecular structure with intermolecular hydrogen bonding. Sm-2 is a one-dimensional chain structure and is further connected by intricate hydrogen bonds into a three-dimensional supramolecular structure. These three compounds exhibit significant characteristic luminescence from the ligand to the central Ln(iii) ion, which is found by solid-state photoluminescence measurement. Sm-2 exhibits a long luminescence lifetime and high fluorescence quantum yield. A slow relaxation phenomenon is observed for the dysprosium compound by measuring the alternating-current susceptibility at low temperature and the underlying mechanism was further confirmed by theoretical calculations.

Correction: Lanthanide complexes based on a conjugated pyridine carboxylate ligand: structures, luminescence and magnetic properties.

[This corrects the article DOI: 10.1039/C9RA10975G.].