Recent Advances in DNA Nanotechnology-Based Sensing Platforms for Rapid Virus Detection.

Several major viral pandemics in history have significantly impacted the public health of human beings. The COVID-19 pandemic has further underscored the critical need for early detection and screening of infected individuals. However, current detection techniques are confronted with deficiencies in sensitivity and accuracy, restricting the capability of detecting trace amounts of viruses in human bodies and in the environments. The advent of DNA nanotechnology has opened up a feasible solution for rapid and sensitive virus determination. By harnessing the designability and addressability of DNA nanostructures, a range of rapid virus sensing platforms have been proposed. This review overviewed the recent progress, application, and prospect of DNA nanotechnology-based rapid virus detection platforms. Furthermore, the challenges and developmental prospects in this field were discussed.

Study on Dynamic Liquid-Carrying Process of Foaming Agent and Establishment of Mathematical Model.

The efficiency of foam drainage gas recovery is predominantly dictated by the performance of the foaming agent. To better understand their behavior, a novel testing apparatus was developed to simulate the foam drainage gas recovery process within the wellbore. Through the dynamic liquid-carrying performance tests of four foaming agents under uniform conditions, it was discerned that there existed significant disparities in the liquid-carrying performance and action duration. Further interface performance analysis disclosed that the liquid-carrying capacity and the duration were correlated with their adsorption capacity and interface activity at the gas-liquid interface. Notably, foaming agents with lower adsorption capacity and higher interfacial activity demonstrated superior liquid-carrying performance and longer action duration. By analyzing the consumption of foaming agents during the liquid-carrying process, five dynamic liquid-carrying equations were derived based on first-order reaction kinetics, the Malthusian population model, and the logistic function. The outcomes demonstrated that all these five equations could precisely delineate the dynamic liquid-carrying process of the foaming agent. During the research, we found that the consumption of the foaming agent in the foam drainage gas recovery process is related to its adsorption behavior at the gas-liquid interface, and revealed that the dynamic liquid-carrying process of foaming agent is the increasing process of liquid-carrying capacity under the continuous consumption of limited foaming agent resources. This laid a foundation for the further exploration of the functional mechanism of the foaming agent in the foam drainage gas recovery process.

Ir Doping Modulates the Electronic Structure of Flower-Shaped Phosphides for Water Oxidation.

Electrolysis of water to produce hydrogen is an efficient, clean, and environmentally friendly hydrogen production method with unlimited development prospects. However, its overall efficiency is hampered by the slow oxygen evolution reaction (OER) with complex electron transfer processes. Therefore, designing efficient and low-cost OER catalysts is the key to solving this problem. In this paper, Ir-doped Co2P/Fe2P (abbreviated as Ir-CoFeP/NF) was grown on nickel foam through the strategies of low amount noble-metal doping and mild phosphating. Phosphide derived from a floral metal-organic framework (MOF) exhibits regular three-dimensional (3D) morphology and large active area, avoiding the stacking of active sites. The addition of Ir can effectively adjust the electronic structure, change the position of the d-band center, and increase active sites, thus enhancing the catalytic activity. Hence, the optimized catalyst exhibits unexpected electrocatalytic OER activity with an ideal overpotential of 213 mV at 10 mA cm-2, as well as a low Tafel slope of 40.63 mV dec-1. Coupling with Pt/C for overall water splitting (OWS), the entire device only needs an ultralow cell voltage of 1.50 V to achieve a current density of 10 mA cm-2. Besides, the OWS can be maintained for more than 70 h. This study demonstrates the superiority of Ir-doped phosphide in accelerating water oxidation.

An AIEE-active Triphenylethylene Derivative with Photoresponsive Character for Latent Fingerprints Detection via a Simple Soaking Method.

Latent fingerprints (LFPs) is one of the most important physical evidence in the criminal scene, playing an important role in forensic investigations. Therefore, developing highly sensitive and convenient materials for the visualization of LFPs is of great significance. We designed and synthesized an organic fluorescent molecule TP-PH with aggregation-induced enhanced emission (AIEE) activity. By simply soaking, blue fluorescent images with high contrast and resolution are readily developed on various surfaces including tinfoil, steel, glass and plastic. Remarkably, LFPs can be visualized within 5 min including the first-, second- and tertiary-level details. In addition, TP-PH exhibits interesting photoactivated fluorescence enhancement properties. Under irradiation of 365 nm UV light with a power density of 382 mW/cm2, the fluorescence quantum yield displays approximately 21.5-fold enhancement. Mechanism studies reveals that the photoactivated fluorescence is attributed to the irreversible cyclodehydrogenation reactions under UV irradiation. This work provides a guideline for the design of multifunctional AIEE fluorescent materials.

STM/TERS observation of (M)-type diphenyl[7]thiaheterohelicene on Ag(111).

The chiral recognition of a self-assembled structure of enantiopure (M)-type 2,13-diphenyl[7]thiaheterohelicene ((M)-Ph-[7]TH) was investigated on a Ag(111) substrate by scanning tunnelling microscopy (STM) and tip-enhanced Raman spectroscopy (TERS). In contrast to previous research of thiaheterohelicene and its derivatives showing zigzag row formation on the Ag(111) substrate, the hexagonal ordered structure was observed by STM. The obtained TERS spectra of (M)-Ph-[7]TH were consistent with the Raman spectra calculated on the basis of density functional theory (DFT), which suggests that (M)-Ph-[7]TH was adsorbed on the substrate without decomposition. The sample bias voltage dependence of STM images combined with the calculated molecular orbitals of (M)-Ph-[7]TH indicates that a phenyl ring was observed as a protrusion at +3.0 V, whereas the helicene backbone was observed at +0.5 V. From these results, a possible model of the hexagonal structure was proposed. Owing to the phenyl ring, the van der Waals interaction between (M)-Ph-[7]TH and the substrate becomes strong. This leads to the formation of the hexagonal structure with the same symmetry as the substrate.

Explainable Deep Learning-Assisted Photochromic Sensor for ß-Lactam Antibiotic Identification.

Photochromic sensors have the advantages of diverse isomers for multi-analysis, providing more sensing information and possessing more recognition units and more sensitivity to external stimulations, but they present enormous complexity with various stimulations as well. Deep learning (DL) algorithms contribute a huge advantage at analyzing nonlinear and multidimensional data, but they suffer from nontransparent inner networks, "black-boxes". In this work, we employed the explainable DL approach to process and explicate photochromic sensing. Spirooxazine metallic complexes were adopted to prepare a multi-state analysis array for ß-Lactams identification and quantitation. A dataset of 2520 unduplicated fluorescence intensity images was collected for convolutional neural network (CNN) operation. The method clearly discriminated six ß-Lactams with 97.98% prediction accuracy and allowed rapid quantification with a concentration range from 1 to 100 mg/L. The photochromic sensing mechanism was verified via molecular simulation and class activation mapping, which explicated how the CNN model assesses the importance of photochromic sensor states and makes a discrimination decision. The explainable DL-assisted analysis method establishes an end-to-end strategy to ascertain and verify the complicated sensing mechanism for device optimization and even new scientific discovery.

Improved Luminous Efficiency of AgInS2 Quantum Dots and Zeolitic Imidazolate Framework-70 Composite for White Light Emitting Diode Applications.

The application of multiple quantum dots (QDs) in the field of white light emitting diodes (WLEDs) is still an important challenge due to their low luminous efficiency and quenching phenomenon. In this paper, we prepared AgInS2 QDs/zeolitic imidazolate framework-70 (AIS/ZIF-70) composite by a microwave hydrothermal method. Owing to the high porosity and stability of ZIF-70, it could effectively prevent quenching issues due to the aggregation of QDs. Since the ZIF-70 and QDs were chemically bonded, the formation of the ZnS layer could effectively passivate the surface defect and thus the quantum yield reached 21.49 % in aqueous solution. The luminous efficiency (LE) of the assembled AIS/ZIF-based WLED was reinforced by 6.8 times with a molar ratio of AgIn/Zn=18, i. e. at 5.26 % molar fraction of ZIF-70. Moreover, the color rendering index (CRI) and correlated color temperature (CCT) of AIS/ZIF-based WLED were 84.3 and 3631 K, respectively, indicating its potential application in solid-state lighting.

Multi-wavelength excited triplet-triplet upconversion microcrystals based on hot-band excitation for optical information encryption.

Multi-wavelength hot-band excitation, forbidden in the conventional Stokes fluorescence mechanism, is found to be available with cascading triplet-triplet annihilation upconversion (TTA-UC). Selective excitation of Pt(II)octaethylporphyrin (PtOEP) by diode lasers with wavelengths of 532 nm, 589 nm, 635 nm, 655 nm, and 671 nm respectively can all induce 9,10-diphenylanthracene (DPA) to emit blue upconversion, with the maximum anti-Stokes shift of 0.95 eV in the microcrystals exposed to air. Whether the zero-vibrational energy level excitation or the hot-vibrational energy level excitation in the ground state, the PtOEP/DPA pair showed triplet-triplet energy transfer (TTET) efficiencies approaching ∼95%. The doped microcrystal samples without encapsulation can emit blue upconversion from green/yellow/red excitation with stability for ∼20 days under atmospheric conditions, demonstrating their potential applications in multiple information encryption.

The effect of triethylamine on dye-sensitized upconversion luminescence and its application in nanoprobes and photostability.

Triethylamine (TEA) is an effective medium for inhibiting dye aggregation and improving the luminescence of dye-sensitized lanthanide-doped upconversion nanoparticles (UCNPs). However, excessive TEA will cause quenching of upconversion luminescence. In this paper, the possible mechanism of TEA affecting upconversion luminescence is discussed. It is found that TEA can enhance the nucleophilicity of the solvent, leading to dye shedding from the nanoparticles. Reducing the dielectric constant of the solvent can make TEA play a more positive role in upconversion luminescence and photostability of dye-sensitized UCNPs. When heptanol is selected as the solvent for CyBSO-sensitized ß-NaYF4:20%Yb3+,2%Er3+ (UNs), TEA can increase the upconversion luminescence by 6.0 times relative to that in methanol. More importantly, the optimal content of TEA in heptanol is 3700 times more than that in methanol. Under the action of large amounts of TEA in heptanol, a novel upconversion nanoprobe for detecting ascorbic acid is developed with a limit of detection of 0.103 µM and high selectivity over potential interfering species. Meanwhile, the high concentration of TEA in heptanol can improve the photostability of CyBSO-sensitized UNs by 10.4 times, which is of paramount importance for the practical application of dye-sensitized UCNPs.

Surface Reconstruction of an FeNi Foam Substrate for Efficient Oxygen Evolution.

Designing earth-abundant electrocatalysts that are highly active, low-cost, and stable for the oxygen evolution reaction (OER) is crucial for electrochemical water splitting. However, in conventional electrode fabrication strategies, NiFe layered double hydroxide (NiFe LDH) catalysts are usually coated onto substrates as external components, which suffers from poor conductivity, easily detaches from the substrate, and hinders their long-term utilization. Herein, the surface-reconstruction strategy is used to synthesize in situ autologous NiFe LDH to increase the surficial active sites numbers. The FeNi foam (FNF) serves as both the metal source and substrate, and the obtained NiFe LDH nanosheets (NSs) are firmly anchored in the monolithic FNF. What needs to be emphasized is that the strategy does not involve any high-temperature or high-pressure processes, apart from a cost-effective etching and a specified drying treatment. The nanostructure of NiFe LDH and the synergistic effect between Fe and Ni simultaneously lead to an enhanced catalytic effect for the OER. Remarkably, the sr-FNF46 requires only an ultralow overpotential of 283 mV to achieve a current density of 100 mA cm-2 for the OER in 1 M KOH electrolyte, and exhibits excellent stability. Thus, the obtained electrode holds promise for electrocatalytic applications. Finally, the formation mechanism of NiFe LDH NSs due to surface reconstruction is investigated and discussed in detail.

Luminescence Ratiometric Nanothermometry Regulated by Tailoring Annihilators of Triplet-Triplet Annihilation Upconversion Nanomicelles.

Triplet-triplet annihilation (TTA) upconversion is a special non-linear photophysical process that converts low-energy photons into high-energy photons based on sensitizer/annihilator pairs. Here, we constructed a novel luminescence ratiometric nanothermometer based on TTA upconversion nanomicelles by encapsulating sensitizer/annihilator molecules into a temperature-sensitive amphiphilic triblock polymer and obtained good linear relationships between the luminescence ratio (integrated intensity ratio of upconverted luminescence peak to the downshifted phosphorescence peak) and the temperature. We also found chemical modification of annihilators would rule out the interference of the polymer concentration and stereochemical engineering of annihilators would readily regulate the thermal sensitivity.

Undaria pinnatifida improves obesity-related outcomes in association with gut microbiota and metabolomics modulation in high-fat diet-fed mice.

Dietary fiber has beneficial effects on obesity-related diseases and gut microbiota, contributing a key role in the interaction between dietary metabolism and host metabolism. Our objective was to investigate the cause of the improvement in multiple types of physiological states with seaweed Undaria pinnatifida treatment on high-fat diet-fed mice and to evaluate whether its consequent anti-adiposity and anti-hyperlipidemic effects are associated with gut microbiota and its metabolomics regulation. U. pinnatifida administration in our experiment was shown to significantly decrease high-fat diet-induced body weight gain, as well as epididymal and abdominal adiposity. U. pinnatifida intake also significantly reduced liver weight and serum triacylglycerol accumulation. We also found that improving effects of U. pinnatifida on high-fat diet-induced metabolic dysfunctions were associated with significant increase in specific bacteria, such as Bacteroides acidifaciens and Bacteroides ovatus, as well as metabolites, including short-chain fatty acids and tricarboxylic acid cycle intermediates. Our result provides a cheap dietary strategy to host metabolism improvement and obesity management. KEY POINTS: • U. pinnatifida improved adipose accumulation and lipid metabolism. • B. acidifaciens and B. ovatus contributed to the beneficial effects of U. pinnatifida. • SCFAs and TCA cycle intermediates were critical to the metabolic outcomes. • Our study provides a cheap dietary strategy for obesity management.

Alginate oligosaccharide improves lipid metabolism and inflammation by modulating gut microbiota in high-fat diet fed mice.

Alginate oligosaccharides are associated with some beneficial health effects. Gut microbiota is one of the most recently identified factors in the development of several metabolic diseases induced by high-fat diet. Our objective was to evaluate how alginate oligosaccharides impact on high-fat diet­induced features of metabolic disorders and whether this impact is related to modulations in the modulation of the gut microbiota. C57BL/6J mice were fed with chow diet, high-fat diet, or high-fat diet supplemented with alginate oligosaccharides for 10 weeks. Alginate oligosaccharide treatment improved lipid metabolism, such as reducing levels of TG and LDL-C and inhibiting expression of lipogenesis genes. Alginate oligosaccharide administration reduced the levels of fasting blood glucose and increased the levels of serum insulin. Alginate oligosaccharide treatment was found to lower the expression of markers of inflammation, including IL1ß and CD11c. Alginate oligosaccharide treatment modulated gut microbial communities and markedly prompted the growth of Akkermansia muciniphila, Lactobacillus reuteri, and Lactobacillus gasseri. Additionally, alginate oligosaccharide intervention significantly increased concentrations of short-chain fatty acids, such as acetic acid, propionic acid, and butyric acid, as well as decreased levels of endotoxin. Alginate oligosaccharides exert beneficial effects via alleviating metabolic metrics induced by high-fat diet, which is associated with increase in A. muciniphila, L. reuteri, and L. gasseri, as well as the release of microbiota-dependent short-chain fatty acids and inhibition of endotoxin levels.

Copper-Catalyzed Radical 1,4-Difunctionalization of 1,3-Enynes with Alkyl Diacyl Peroxides and N-Fluorobenzenesulfonimide.

Many reactions involving allenyl ion species have been studied, but reactions involving allenyl radicals are less well understood, perhaps because of the inconvenience associated with the generation of short-lived allenyl radicals. We describe here a versatile method for the generation of allenyl radicals and their previously unreported applications in the intermolecular 1,4-carbocyanation and 1,4-sulfimidocyanation of 1,3-enynes. With the assistance of the trifunctional reagents, alkyl diacyl peroxides or N-fluorobenzenesulfonimide, a range of synthetically challenging multisubstituted allenes can be prepared with high regioselectivity. These multisubstituted allenes can be easily transformed into synthetically useful structures such as fluorinated vinyl cyanides, lactones, functionalized allenyl amides, 1-aminonaphthalenes, and pyridin-2(1 H)-ones, and several novel transformations are reported. The results of radical scavenger and radical clock experiments are consistent with the proposed allenyl radical pathway. Density functional theory (DFT) and IR spectroscopy studies suggest the formation of an isocyanocopper(II) species in the ligand exchange step. On the basis of the results of IR, DFT, and diastereoselectivity studies, an isocyanocopper(II)/copper(I) catalytic cycle is proposed, which differs from the previously considered Cu(III) mechanism in cyanation reactions.

A green solvent for operating highly efficient low-power photon upconversion in air.

d-Limonene, obtained from the rind of citrus fruits, was demonstrated as a green solvent to realize air-stable and highly efficient triplet-triplet annihilation photon upconversion (TTA-UC). This natural low-toxic compound also contributed to noncoherent UC excited by a solar simulator in air, making TTA-UC materials promising candidates in solar energy and other practical applications. The rapid deoxygenating ability of d-limonene was thoroughly investigated. This system demonstrated very good UC performance for a fluid solution under ambient conditions. Besides, other eight types of terpene were also explored to enrich the alternatives for air-stable TTA-UC in protic and aprotic fluidic environments. This work provides a terpene-based protective platform for oxygen-sensitive TTA-UC applications ranging from life science to photonic devices.

Ginkgo biloba sarcotesta polysaccharide inhibits inflammatory responses through suppressing both NF-κB and MAPK signaling pathway.

BACKGROUND: Polysaccharides, common components of natural products extensively studied as dietary supplements and functional foods, have been found to have various activities. In the present study, a water-soluble polysaccharide, namely GBSP3a, was isolated and purified from G. biloba sarcotesta. The anti-inflammatory activity of GBSP3a in lipopolysaccharide (LPS)-induced RAW264.7 macrophages and the potential underlying molecular mechanisms were then assessed. RESULTS: GBSP3a exerted its anti-inflammatory effect by remarkably inhibiting the secretion of pro-inflammatory mediators and cytokines, including nitric oxide (NO), prostaglandin E2 (PGE2 ), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1ß (IL-1ß) in LPS-stimulated RAW264.7 macrophages. Excessive mRNA and protein expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were dose-dependently inhibited by GBSP3a in LPS-stimulated RAW264.7 cells. Further research suggested that the anti-inflammatory effect of GBSP3a can be attributed to the modulation of the NF-κB and MAPK signaling pathways. CONCLUSION: GBSP3a exhibits anti-inflammatory activity and exerts its anti-inflammatory effect probably through suppressing both NF-κB and MAPK signaling pathway, indicating that GBSP3a could be used for the development of anti-inflammatory agent or nutraceuticals. © 2018 Society of Chemical Industry.

Copper(I)-catalyzed tandem reaction: synthesis of 1,4-disubstituted 1,2,3-triazoles from alkyl diacyl peroxides, azidotrimethylsilane, and alkynes.

A copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction for the synthesis of 1,4-disubstituted 1,2,3-triazoles from alkyl diacyl peroxides, azidotrimethylsilane, and terminal alkynes is reported. The alkyl carboxylic acids is for the first time being used as the alkyl azide precursors in the form of alkyl diacyl peroxides. This method avoids the necessity to handle organic azides, as they are generated in situ, making this protocol operationally simple. The Cu(I) catalyst not only participates in the alkyl diacyl peroxides decomposition to afford alkyl azides but also catalyzes the subsequent CuAAC reaction to produce the 1,2,3-triazoles.

Iron-Catalyzed Radical Decarboxylative Oxyalkylation of Terminal Alkynes with Alkyl Peroxides.

An iron-catalyzed oxyalkylation of alkynes with alkyl peroxides as the alkylating reagents has been investigated. Alkyl peroxides are readily available from aliphatic acids and serve simultaneously as the alkylating reagents and internal oxidants. Primary, secondary, and tertiary alkyl groups of aliphatic acids were readily incorporated into C-C triple bonds and diverse α-alkylated ketones were synthesized. Mechanism studies revealed that this reaction involves highly reactive alkyl free radicals. A unique equilibrium between lauric acid and water catalyzed by the iron(III) catalyst was observed.

Drinking water treatment using a submerged internal-circulation membrane coagulation reactor coupled with permanganate oxidation.

A submerged internal circulating membrane coagulation reactor (MCR) was used to treat surface water to produce drinking water. Polyaluminum chloride (PACl) was used as coagulant, and a hydrophilic polyvinylidene fluoride (PVDF) submerged hollow fiber microfiltration membrane was employed. The influences of trans-membrane pressure (TMP), zeta potential (ZP) of the suspended particles in raw water, and KMnO4 dosing on water flux and the removal of turbidity and organic matter were systematically investigated. Continuous bench-scale experiments showed that the permeate quality of the MCR satisfied the requirement for a centralized water supply, according to the Standards for Drinking Water Quality of China (GB 5749-2006), as evaluated by turbidity (<1 NTU) and total organic carbon (TOC) (<5mg/L) measurements. Besides water flux, the removal of turbidity, TOC and dissolved organic carbon (DOC) in the raw water also increased with increasing TMP in the range of 0.01-0.05MPa. High ZP induced by PACl, such as 5-9mV, led to an increase in the number of fine and total particles in the MCR, and consequently caused serious membrane fouling and high permeate turbidity. However, the removal of TOC and DOC increased with increasing ZP. A slightly positive ZP, such as 1-2mV, corresponding to charge neutralization coagulation, was favorable for membrane fouling control. Moreover, dosing with KMnO4 could further improve the removal of turbidity and DOC, thereby mitigating membrane fouling. The results are helpful for the application of the MCR in producing drinking water and also beneficial to the research and application of other coagulation and membrane separation hybrid processes.

Correction: Photon upconversion: from two-photon absorption (TPA) to triplet-triplet annihilation (TTA).

Correction for 'Photon upconversion: from two-photon absorption (TPA) to triplet-triplet annihilation (TTA)' by Changqing Ye et al., Phys. Chem. Chem. Phys., 2016, DOI: .