Sensitive and reliable hybrid nanosensor (Co2+-CDs@R-CDs) for ratiometric fluorescent and colorimetric detecting NO2.

A ratiometric fluorescent and colorimetric detecting assay for NO2- was realized by a hybrid nanosensor (Co2+-CDs@R-CDs) utilizing firstly through the redox reaction of nitrite (NO2-) with Co2+, of which the hybrid nanosensor Co2+-CDs@R-CDs was fabricated by Co2+-doped carbon dots (Co2+-CDs) and a reference of red-emitting carbon dots (R-CDs). The ratiometric fluorescent linear detection range of NO2- was 2.5-45 µM and the limit of detection (LOD) was 0.068 µM with the response time of 120 s. While, the colorimetric linear detection range of NO2- was 2.5-60 µM and the LOD was 0.075 µM. In addition, a portable smartphone system which could measure the R (red), G (green), and B (blue) values of the fluorescence and the visible color of the coated Co2+-CDs@R-CDs paper strip-based sensor had also been developed and successfully applied to detect NO2- in sausage, pickles and tap water samples.

AtHD2D is involved in regulating lateral root development and participates in abiotic stress response in Arabidopsis.

Roots are essential to terrestrial plants, as their growth and morphology are crucial for plant development. The growth of the roots is affected and regulated by several internal and external environmental signals and metabolic pathways. Among them, chromatin modification plays an important regulatory role. In this study, we explore the potential roles of the histone deacetylase AtHD2D in root development and lay the foundation for further research on the biological processes and molecular mechanisms of AtHD2D in the future. Our study indicates that AtHD2D affects the root tip microenvironment homeostasis by affecting the gene transcription levels required to maintain the root tip microenvironment. In addition, we confirmed that AtHD2D is involved in regulating Arabidopsis lateral root development and further explained the possible role of AtHD2D in auxin-mediated lateral root development. AtHD2D can effectively enhance the resistance of Arabidopsis thaliana to abiotic stress. We believe that AtHD2D is involved in coping with abiotic stress by promoting the development of lateral roots. Overexpression of AtHD2D promotes the accumulation of reactive oxygen species (ROS) in roots, indicating that AtHD2D is also involved in developing lateral roots mediated by ROS. Previous studies have shown that the overexpression of AtHD2D can effectively enhance the resistance of Arabidopsis thaliana to abiotic stress. Based on our data, we believe that AtHD2D participates in the response to abiotic stress by promoting the development of lateral roots. AtHD2D-mediated lateral root development provides new ideas for studying the mechanism of HDAC protein in regulating root development.

Fabrication of a porous Urea@MIL-100(Fe)/CI-MCC/SA hydrogel for All-In-One adsorption, removal and fluorescence monitoring of nitrite.

In this paper, a novel All-In-One Urea@MIL-100(Fe)/CI-MCC/SA hydrogel platform was generated by microcrystalline cellulose (MCC) functionalized with pH-response probe (CI), MIL-100 (Fe) and sodium alginate (SA), which was as a carrier of urea to adsorb, remove and monitor NO2-. Under acidic condition, the fluorescent hydrogel platform could produce N2, CO2 and H2O through the diazotization and redox reaction between urea and NO2- with a removal efficiency up to 99.8%, and could also character a good adsorption property for NO2- due to the positive charges of protonation (the maximum adsorption capacity was 21.67 mg g-1), and the adsorption kinetics conformed to pseudo-second-order model. By carried out the NO2- removal step in fluorescent hydrogel platform, NO2- could also be detected indirectly by sensing the changes of pH within 15 min. The linear response range was 0-0.005 M, and the detection limit (LOD) was 74 µM. These results demonstrated that this All-In-One Urea@MIL-100(Fe)/CI-MCC/SA hydrogel platform had great potential in environment. This strategy for the removal and monitoring of NO2- could be employed to related applications in water purification and environmental protection. ENVIRONMENTAL IMPLICATION: Nitrite is one of the important indicators of water monitoring, which is harmful to human and environment. The removal and monitoring of nitrite in industrial wastewater and surface water is very important, but there are no studies about it at present. Based on the fact that urea can react with nitrite to produce green products, we synthesized a novel functional hydrogel to achieve adsorption, removal and fluorescence monitoring of nitrite for the first time. Besides, the practicability of the material in environmental water samples was verified through the detection of nitrite in simulated wastewater.

Organophosphate Level Evaluation for the Poisoning Treatment by Enzyme Activation Regeneration Strategy with Oxime-Functionalized ZIF-8 Nanoparticles.

In this work, two nanometal-organic frameworks (NMOFs) of ZIF-8-1 and ZIF-8-2 were designed and synthesized with a "missing linker" defects strategy by using Oxime-1 and Oxime-2 as coligands, respectively. ZIF-8-2 exhibited an excellent performance in comparison to that of ZIF-8-1 in activating and regenerating the activity of BChE suppressed by demeton-S-methyl (DSM) and could rapidly detoxify DSM in poisoned serum samples within 24 min. Additionally, the synthesized fluorescence probe of IND-BChE with high quantum yields, large Stokes shifts, and superior water solubility could be used for the detection of both butyrylcholinesterase (BChE) and DSM in a lower LOD of 0.63 mU/mL (BChE) and 0.086 µg/mL (DSM). By the difference in fluorescent intensity of IND-BChE with and without ZIF-8-2, a highly linear relationship of IND-BChE with DSM concentration was found (R2 = 0.9889), and the LOD was 0.073 µg/mL. In addition, an intelligent detection platform of ZIF-8-2@IND-BChE@agarose hydrogel combined with a smartphone formed a point-of-care test for DSM -poisoned serum samples and also realized satisfactory results. Unlike other detection methods of nerve agents, this assay first combined an NMOF reactivator for detoxification and detection of BChE enzyme activity and then quantification of OP nerve agents, which was of great significance in treatment of organophosphate poisoning.

Simple method for visual detection of nitrite using fluorescence and colorimetry by poly (tannic acid) nanoparticles.

The nitration reaction of nitrite and phenolic substances was first used to identify and detect NO2- by taking fluorescent poly (tannic acid) nanoparticles (FPTA NPs) as sensing platform. With the low cost, good biodegradable and convenient water-soluble FPTA NPs, a fluorescent and colorimetric dual modes detecting assay was realized. In fluorescent mode, the linear detection range of NO2- was 0-36 µM, the LOD was as low as 3.03 nM, and the response time was 90 s. In colorimetric mode, the linear detection range of NO2- was 0-46 µM, and the LOD was as low as 27 nM. Besides, a smartphone with FPTA NPs@ agarose hydrogel formed a portable detection platform to test the fluorescent and visible color changes of FPTA NPs for NO2- sensing as well as for accurate visualization and quantitative detection of NO2- in actual water and food samples.

Ultrasensitivity Detecting AChE through "Covalent Assembly" and Signal Amplification Strategic Approaches and Applied to Screen Its Inhibitor.

An ultrasensitivity detecting assay for acetylcholinesterase (AChE) activity was developed based on "covalent assembly" and signal amplification strategic approaches. After hydrolyzing thioacetylcholine by AChE and participation of thiol in a self-inducing cascade accelerated by the Meldrum acid derivatives of 2-[bis(methylthio) methylene] malonitrile (CA-2), mercaptans triggered an intramolecular cyclization assembly by the probe of 2-(2,2-dicyanovinyl)-5-(diethylamino) phenyl 2,4-dinitrobenzenesulfonate (Sd-I) to produce strong fluorescence. The limit of detection for AChE activity was as low as 0.0048 mU/mL. The detection system also had a good detecting effect on AChE activity in human serum and could also be used to screen its inhibitors. By constructing a Sd-I@agarose hydrogel with a smartphone, a point-of-care detection of AChE activity was achieved again.