[Characteristics of Cd, As, and Pb in Soil and Wheat Grains and Health Risk Assessment of Grain-Cd/As/Pb on the Field Scale].

In recent years, heavy metal pollution in farmlands has become increasingly serious because of human activities such as metal smelting, sewage irrigation, and road traffic in China. A field survey was conducted to investigate characteristics of Cd, As, and Pb in soil and wheat grains and assess the health risk of grain-Cd/As/Pb to humans on the fields scale. The farmland was influenced by smelter and sewage irrigation in the attitude and by road traffic in the horizon. The results showed that in farmland soil with moderate pollution levels, Cd, As, and Pb concentrations in soil samples all exceeded the risk screening values of farmland soil (GB 15618-2018), and the exceeding rates were 100%, 100%, and 36.7% respectively; the exceeding rates of Cd and Pb concentrations in wheat grains were 76.7% and 13.3%, respectively (GB 2762-2017). Distance from smelter, river of sewage irrigation, and road had no significant effect on Cd, As, and Pb concentrations in soil but had a significant effect on Cd and As concentrations in wheat grains, with the median Cd and As concentrations of the closest group being 14.9% and 41.8%, respectively, higher than the highest group (P<0.05). The Pb concentrations in soil and wheat grains were influenced by road traffic; the median Pb concentrations of the closest group were 78.9% and 471%, respectively, higher than the highest group (P<0.05). Cd and As in wheat grains have carcinogenic risks (Ri>1×10-4), RCd > RAs, Rchildren > Radult, while Pb poses no health risks in this farmland.

Structural analysis of glycosaminoglycans from Colla corii asini by liquid chromatography-electrospray ion trap mass spectrometry.

Colla corii asini (CCA) made from donkey-hide has been widely used as a traditional animal-based Chinese medicine. Chondroitin sulfate (CS), dermatan sulfate (DS) and hyaluronic acid (HA) are structurally complex classes of glycosaminoglycans (GAGs) that have been implicated in a wide range of biological activities. However, their possible structural characteristics in CCA are not clear. In this study, GAG fractions containing CS/DS and HA were isolated from CCA and their disaccharide compositions were analyzed by high sensitivity liquid chromatography-ion trap/time-of-flight mass spectrometry (LC-MS-ITTOF). The result showed that CS/DS/HA disaccharides were detected in the three lower salt fractions from anion-exchange chromatography. The sulfation patterns and densities of CS/DS chains in these fractions differed greatly, while HA chains varied in their chain lengths. The quantitative analysis first revealed that the amount of GAGs in CCA varied significantly in total and in each fraction. This novel structural information could help clarify the possible involvement of these polysaccharides in the biological activities of CCA.

Plasmonic hot electron transfer-induced multicolor MoO3-x-based chromogenic system for visual and colorimetric determination of silver(I).

A plasmonic hot electron transfer-induced multicolor chromogenic system is described for label-free visual colorimetric determination of silver(I). The chromogenic system consists of plasmonic MoO3-x nanosheets with oxygen vacancies and Ag(I). Under white light-emitting diode (LED) excitation, energetic hot hole-electron pairs are formed on the surface of the blue MoO3-x nanosheets. The resulting hot electrons are transferred to Ag(I) upon which it becomes reduced. This results in the generation of yellow silver nanoparticles. Simultaneously, the hot holes lead to the oxidation of the MoO3-x nanosheets to yield colorless MoO3 nanosheets. Similarly, energetic hot hole-electron pairs can also be generated on the surface of AgNPs under white LED irradiation, which contributes to the reduction of Ag(I) and the oxidation of MoO3-x. Overall, a colorful transition from blue to green and finally to yellow can be observed. This multicolor chromogenic system was applied to the colorimetric determination of Ag(I) in the 33-200 µM concentration range and a 0.66 µM limit of detection, at analytical wavelengths of 430 and 760 nm. The method also is amenable to semi-quantitative visual determination of Ag(I). Graphical abstractSchematic representation of plasmonic hot electron transfer-induced multicolor MoO3-x-based chromogenic system for visual and colorimetric determination of silver(I).

Chemically modified mesoporous wood: a versatile sensor for visual colorimetric detection of trinitrotoluene in water, air, and soil by smartphone camera.

There is great interest in detection of the level of 2,4,6-trinitrotoluene (TNT) explosive due to its importance in public security and environmental protection fields. The conventional chemical sensors do not simultaneously realize simple, rapid, sensitive, selective, and direct detection of TNT in different medium without sample pretreatment. Here we present a modified wood-based chemical sensor for visual colorimetric detection of TNT in water, air, and soil. The natural wood undergoes a delignified process, which is further functionalized by 3-aminopropyltriethoxysilane (APTES). When TNT solutions are introduced, the wood-based sensor shows a colorimetric transition from light yellow to brown for naked-eye readout because of the generation of Meisenheimer complex between APTES and TNT. The photographs are collected by smartphone camera, and the RGB components are extracted to calculate the adjusted intensity for qualitative detection of TNT. This visual colorimetric sensor for TNT solution displays a linearity in the range of 0.01-5 mM with a limit of detection of 3 µM. In addition, by taking advantage of its inherent mesostructure, the wood-based sensor can be employed for visual detection of TNT vapor as well. Furthermore, it is also able to directly detect TNT in wet soil samples based on capillary action, in which TNT carried by water transports upward along the wood microchannel, triggering the generation of Meisenheimer complex. Graphical Abstract.

A single 9-mesityl-10-methylacridinium ion as a solvatochromic sensor array for multicolor visual discrimination of solvents.

We report a single 9-mesityl-10-methylacridinium ion (Acr+-Mes) as a solvatochromic sensor array for multicolor visual discrimination of solvents. The composite fluorescent response of Acr+-Mes to polarity, dispersed state, and lone-pair-π interactions produces different colors when it is dissolved in various solvents. The corresponding RGB values as sensing elements are extracted to create distinct fluorescence response patterns for each solvent. With the help of principal component analysis, common solvents, such as water (H2O), absolute ethanol (EtOH), acetonitrile (MeCN), dimethyl sulfoxide (DMSO), acetone (CO(Me)2), dichloromethane (DCM), trichloromethane (TCM), tetrahydrofuran (THF), toluene (PhMe), and tetrachloromethane (CCl4), are successfully discriminated and identified with an accuracy of 100%. What's more, this sensor array can also discriminate binary solvent mixtures and quantitatively detect DMSO in organic and inorganic solvents.

Analysis of Heparan sulfate/heparin from Colla corii asini by liquid chromatography-electrospray ion trap mass spectrometry.

Colla corii asini (CCA) made from donkey-hide has been widely used as a health-care food and an ingredient of traditional Chinese medicine. Heparan sulfate (HS)/heparin is a structurally complex class of glycosaminoglycans (GAGs) that have been implicated in a wide range of biological activities. However, their presence within CCA, and their possible structural characteristics, were previously unknown. In this study, GAG fractions containing HS/heparin were isolated from CCA and their disaccharide compositions were analyzed by high sensitivity liquid chromatography-ion trap/time-of-flight mass spectrometry (LC-MS-ITTOF). This revealed that, in addition to the eight commonly seen HS disaccharides, the four rare N-unsubstituted disaccharides were also detected in significant quantities. The disaccharide compositions varied significantly between HS/heparin fractions indicating chains with differing domain structures. This novel structural information may lead to a better understanding of the biological activities (i.e. anticoagulation and antitumor action) of CCA.

Contrary logic pairs and circuits using a visually and colorimetrically detectable redox system consisting of MoO3-x nanodots and 3,3'-diaminobenzidine.

Logic systems that yield two or more signal outputs in the presence of the input are scarce. A universal logic system consisting of plasmonic MoO3-x nanodots and 3,3'-diaminobenzidine (DAB) for fabrication of visual contrary logic pairs and circuits are presented here. They do not require the use of expensive instrumentation but can be visually read. It is based on the facts that the blue dispersion of MoO3-x nanodots turns to colorless after oxidation, while the colorless reagent DAB is oxidized by various oxidants to generate a brown color. On this basis, the complete contrary logic pairs and circuits such as YES-NOT, AND-NAND, OR-NOR, XOR-XNOR, INH-IMH, and MAJ-MIN can be fabricated. Various oxidants serve as inputs, and absorbances as outputs. A smart logic voting system with "one-vote deny" function is also described that is based on the cascade of MAJ logic circuit and INH logic gate using ascorbic acid (AA) as the superior denier. All the logic operations can visually read due to the appearance of distinct color changes. Graphical abstract Schematic presentation of the contrary logic pairs and circuits using a visually and colorimetrically detectable redox system consisting of MoO3-x nanodots and 3,3'-diaminobenzidine.

Compartmentalizing Incompatible Tandem Reactions in Pickering Emulsions To Enable Visual Colorimetric Detection of Nitramine Explosives Using a Smartphone.

We report a visual colorimetric assay for detection of nitramine explosives such as 1,3,5-trinitro-1,3,5-triazinane (RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) using a smartphone. This assay is based on compartmentalizing incompatible tandem reactions in Pickering emulsions. The alkaline hydrolysis of RDX or HMX in one Pickering emulsion produces nitrite ions, which autodiffuse into the other Pickering emulsion to form nitrous acid. It oxidizes the 3,3',5,5'-tetramethylbenzidine (TMB) to generate yellow TMB diimine. The RGB component change of the optical images is applied to quantitatively determine the RDX and HMX at different reaction temperatures. A distinct color change occurs at RDX and HMX concentrations of 1.2 and 12 µM, respectively. The adjusted intensity increases linearly with the increase of the logarithms of the concentrations of RDX and HMX in the range of 1.2-90 µM and 12-90 µM, respectively. The limits of detection of RDX and HMX are 96 and 110 nM, respectively. Importantly, this assay is employed for the detection of RDX and HMX in real water, proving the applicability of the assay in real-world samples.

Visible Light-Activatable Oxidase Mimic of 9-Mesityl-10-Methylacridinium Ion for Colorimetric Detection of Biothiols and Logic Operations.

In this work, 9-mesityl-10-methylacridinium ion (Acr+-Mes) is found to act as an effective photocatalyst mimicking the function of oxidase. Upon visible light illumination, the excited Acr+-Mes is able to exhibit superior enzymatic catalytic activity for small molecular substrates as well as protein biomacromolecule (cytochrome c). The experiment results demonstrate that the Acr+-Mes oxidase mimic shows higher affinity to 3,3',5,5'-tetramethylbenzidine (TMB) than natural horseradish peroxidase or the reported molecule oxidase mimic. The reaction mechanism is ascribed to the strong oxidation property of the long-lived electron-transfer state (Acr•-Mes•+) and the electron transfer from Acr•-Mes radical to dissolved oxygen to generate superoxide radicals, which can easily oxidize various substrates. On the basis of these observations, the light-activatable Acr+-Mes with an oxidase-like activity as the probe is utilized for cost-effective, sensitive, and highly selective colorimetric detection of two biothiols (L-cysteine and L-glutathione). The lowest detectable concentrations of L-Cys and L-GSH is 100 nM, which is lower than that of most of the reported methods for biothiols. Beyond this, we construct a series of visual molecular logic gates (AND, INH, and NOR) using the oxidase mimic-involved reaction systems.

Visual colorimetric detection of tin(II) and nitrite using a molybdenum oxide nanomaterial-based three-input logic gate.

We report a molybdenum oxide (MoO3) nanomaterial-based three-input logic gate that uses Sn2+, NO2-, and H+ ions as inputs. Under acidic conditions, Sn2+ is able to reduce MoO3 nanosheets, generating oxygen-vacancy-rich MoO3-x nanomaterials along with strong localized surface plasmon resonance (LSPR) and an intense blue solution as the output signal. When NO2- is introduced, the redox reaction between the MoO3 nanosheets and Sn2+ is strongly inhibited because the NO2- consumes both H+ and Sn2+. The three-input logic gate was employed for the visual colorimetric detection of Sn2+ and NO2- under different input states. The colorimetric assay's limit of detection for Sn2+ and the lowest concentration of NO2- detectable by the assay were found to be 27.5 nM and 0.1 µM, respectively. The assay permits the visual detection of Sn2+ and NO2- down to concentrations as low as 2 µM and 25 µM, respectively. The applicability of the logic-gate-based colorimetric assay was demonstrated by using it to detect Sn2+ and NO2- in several water sources.

Versatile Visual Logic Operations Based on Plasmonic Switching in Label-Free Molybdenum Oxide Nanomaterials.

Despite some visual colorimetric chemical logic gates having been reported, a complete set of six basic logic gates have not been realized to date. Moreover, the application of the reported logic gates needs to be further extended. Herein, the label-free molybdenum oxide nanomaterials are presented for the construction of a new visual colorimetric molecular computing system. A complete set of six basic colorimetric logic gates (OR, AND, NOR, NAND, XOR, XNOR) and the INH logic gate are realized based on plasmonic switching in MoO3 nanomaterials. In addition, the rational integration of different logic gates into a 1:2 demultiplexer circuit is also testified.