Spatial Metallomics Reveals Preferable Accumulation of Methylated Selenium in a Single Seed of the Hyperaccumulator Cardamine violifolia†.

Cardamine violifolia is a Se hyperaccumulator found in Enshi, China. In this study, spatial metallomics was applied to visualize the distribution and speciation of Se in a single seed of C. violifolia. It was found that Se reached 1729.89 ± 28.14 mg/kg and the main Se species were SeCys and SeMet in bulk seeds. Further in situ study on a single seed found that the methylated Se species located mostly in the episperm. This is the first visualized evidence of the in situ distribution of methylated Se species in the seeds of C. violifolia. In all, spatial metallomics finds a preferable accumulation of methylated Se species in the seed coat, which deepens the understanding of the tolerance of Se by C. violifolia. The protocol applied in this study may also be used for the understanding of the tolerance of heavy metals/metalloids in other hyperaccumulators.

Nano-WSe2 Is Absorbable and Transformable by Rice Plants.

As typical transition metal dichalcogenides (TMDC), tungsten selenide (WSe2) nanosheets (nano-WSe2) are widely used in various fields due to their layered structures and highly tunable electronic and magnetic properties, which results in the unwanted release of tungsten (W) and selenium (Se) into the environment. However, the environmental effects of nano-WSe2 in plants are still unclear. Herein, we evaluated the impacts and fate of nano-WSe2 and micro-WSe2 in rice plants (Oryza sativa L.). It was found that both nano-WSe2 and micro-WSe2 did not affect the germination of rice seeds up to 5000 mg/L but nano-WSe2 affected the growth of rice seedlings with shortened root lengths. The uptake and transportation of WSe2 was found to be size-dependent. Moreover, W in WSe2 was oxidized to tungstate while Se was transformed to selenocysteine, selenomethionine, SeIV and SeVI in the roots of rice when exposed to nano-WSe2, suggesting the transformation of nano-WSe2 in rice plants. The exposure to nano-WSe2 brought lipid peroxidative damage to rice seedlings. However, Se in nano-WSe2 did not contribute to the synthesis of glutathione peroxidase (GSH-Px) since the latter did not change when exposed to nano-WSe2. This is the first report on the impacts and fate of nano-WSe2 in rice plants, which has raised environmental safety concerns about the wide application of TMDCs, such as WSe2 nanosheets.

Acetylcholinesterase Activity Monitoring and Natural Anti-neurological Disease Drug Screening via Rational Design of Deep Eutectic Solvents and CeO2-Co(OH)2 Nanosheets.

The activity monitoring of acetylcholinesterase (AChE) and the screening of its inhibitors are critical for the diagnosis and therapy of neurological diseases. Herein, CeO2-Co(OH)2 nanosheets were synthesized for the first time in a newly designed deep eutectic solvent (DES) composed of l-proline and Ce(NO3)3·6H2O, and a colorimetric assay was developed for quantitative detection of AChE and anti-neurological disease drug screening. Impressively, CeO2-Co(OH)2 composites prepared in DESs have more prominent oxidase-like activity than Co(OH)2, CeO2, and CeO2-Co(OH)2 produced in aqueous solution. The mechanism study shows that the oxygen vacancies of CeO2-Co(OH)2 play a vital role in oxidase-like catalysis. Based on their excellent oxidase-like activity, the CeO2-Co(OH)2 nanosheets have been successfully applied for highly sensitive and selective detection of AChE with a linear range of 0.2-20 mU/mL. This strategy can also be used for inhibitor screening. The sensor displays an excellent linear response in the range of 0.001-2 µg/mL toward an irreversible inhibitor (paraoxon-ethyl). Moreover, five alkaloids, namely, berberine hydrochloride, caffeine, camptothecin, matrine, and evodiamine, were screened by using neostigmine bromide as a control; berberine hydrochloride exhibited a good inhibitory effect on AChE with an IC50 of 0.94 µM, while the other four had no obvious inhibitory effect. The mechanism of the different effects of alkaloids on inhibiting acetylcholinesterase activity was explored via molecular docking and kinetic simulation.

[Research on regional distribution and industrial status analysis of genuine medicinal resources of flowers in Henan province].

Flower medicinal materials usually refer to Chinese medicinal materials with a complete flower,inflorescence,or part of a flower as the different medicinal parts,they have an important share in the Chinese herbal medicine market and appeared frequently in Chinese medicine prescriptions. Firstly,the species and regional distribution of the flower medicinal materials resources in China were briefly summarized. Secondly,the characteristics,yield,producing area and origin distribution of the main flower medicinal materials in Henan province were discussed. Finally,the present situation and the main problems of the flower medicinal materials industry in Henan province were comprehensively analyzed,and the corresponding industrial development countermeasures were put forward.This research was intended to provide decision-making demonstration and scientific basis for the rational exploitation and utilization of resources,breeding of new varieties,planting division,production layout and the healthy and sustainable development of the flower medicinal materials industry in Henan province.

Intracellular Zinc Quantification by Fluorescence Imaging with a FRET System.

Fluorescence imaging of cellular metals is widely reported. However, the quantification of intracellular metals with fluorescence imaging is so far not feasible and highly challenging. In this work, a ratiometric probe with two fluorescently labeled complementary DNA strains is designed for intracellular zinc quantification via fluorescence imaging, based on fluorescence resonance energy transfer (FRET) from carbon dots (CDs) to fluorescein (FAM). The donor CDs are modified with a Zn2+ aptamer, whereas the receptor FAM is conjugated with the complementary DNA sequence to ensure selectivity. MCF-7 cells are cultured sequentially with Zn2+ (20, 40, 55, 70, 85, and 100 µmol L-1) and CDs-FAM (100 µg mL-1), which is used for fluorescence imaging (at λex = 405 nm and λem = 440-490 nm for CDs, λem = 500-550 nm for FAM) to provide a relative fluorescence ratio (( F - F0)/ F0, F = ICDs/ IFAM), followed by quantifying intracellular zinc with ICPMS. A linear correlation is achieved between the relative fluorescence ratio in fluorescence images and the intracellular zinc content derived by ICPMS, which facilitates intracellular zinc quantification via fluorescence imaging. It is especially useful for real-time tracing of intracellular zinc during the cell culturing process or in vivo. The cellular uptake of Zn2+ by MCF-7 cells is further evaluated with this approach by culturing with 100 µmol L-1 of Zn2+ for different times, and a maximum uptake of 60.5 fg per cell is observed at an incubation time of 60 min. This value is further demonstrated well by ICPMS detection.