Ectopic expression of an Old Yellow Enzyme (OYE3) gene from Saccharomyces cerevisiae increases the tolerance and phytoremediation of 2-nitroaniline in rice

2-nitroaniline (2-NA) is an environmental pollutant and has been extensively used as intermediates in organic synthesis. The presence of 2-NA in the environment is not only harmful for aquatic life but also mutagenic for human beings. In this study, we constructed transgenic rice expressing an Old Yellow Enzyme gene, ScOYE3, from Saccharomyces cerevisiae. The ScOYE3 transgenic plants were comprehensively investigated for their biochemical responses to 2-NA treatment and their 2-NA phytoremediation capabilities. Our results showed that the rice seedlings exposed to 2-NA stress, showed growth inhibition and biomass reduction. However, the transgenic plants exhibited strong tolerance to 2-NA stress compared to wild-type plants. Ectopic expression of ScOYE3 could effectively protect transgenic plants against 2-NA damage, which resulted in less reactive oxygen species accumulation in transgenic plants than that in wild-type plants. Our phytoremediation assay revealed that transgenic plants could eliminate more 2-NA from the medium than wild-type plants. Moreover, omics analysis was performed in order to get a deeper insight into the mechanism of ScOYE3-mediated 2-NA transformation in rice. Altogether, the function of ScOYE3 during 2-NA detoxification was characterized for the first time, which serves as strong theoretical support for the phytoremediation potential of 2-NA by Old Yellow Enzyme genes.

Bio-mineralized tin/bismuth oxide nanoparticles with silk fibroins for efficient electrochemical detection of 2-nitroaniline in river water samples

In recent years, the usage of nitroaniline has played a vital role in pharmaceutical formulations as it is a crucial ingredient in the synthesis of pesticides and dyes. However, the level of nitroaniline existing in industrial waste keeps rising the environmental contamination. Thus, monitoring of active nitro-residuals becomes more significant in reducing the toxicity of the ecosystem. Therefore, we have taken an attempt to evaluate the hazardous pollutant 2-nitroaniline (2-NA) using the electrocatalyst viz., tin-doped bismuth oxide inserted on a biopolymer silk fibroin composite modified glassy carbon electrode (Sn-Bi₂O₃/SF@GCE). The Sn-Bi₂O₃/SF nanocomposite was synthesized through hydrothermal and co-precipitation methods. The physicochemical properties of the prepared Sn-Bi₂O₃/SF hybrid composite were examined by conventional microscopy and spectroscopic techniques like FE-SEM, HR-TEM, XRD, FTIR, Raman, and XPS. Furthermore, the bio-mineralized Sn-Bi₂O₃/SF@GCE displayed a wide linear range (0.009 μM-785.7 μM) and a lower detection limit (3.5 nM) with good sensitivity for 2-NA detection under the optimum conditions. The result shows that the Sn-Bi₂O₃/SF-modified GCE has good reproducibility, repeatability, and excellent selectivity for 2-NA detection in the presence of other co-interfering compounds. Moreover, the practical applicability of Sn-Bi₂O₃/SF@GCE sensors was investigated for the effective detection of 2-NA in real river water samples, revealing good recovery results.

Highly efficient and selective heterogeneous catalytic reduction of 2-nitroaniline by cerium oxide nanocatalyst under microwave irradiation

Efficient nanocatalyst with incredible performance is highly demanding in a heterogeneous catalysis system. Herein, we report the facile fabrication of uniform and highly stable Cerium Oxide nanoparticles (CeO₂ NPs), through chemical precipitation method using sodium hydroxide as reducing agent. The synthesized material is characterized through highly sophisticated techniques including UV-Visible, FT-IR, SEM, AFM, XRD, and Zeta Sizer- Potential to check the particle formation, surface morphology, topography, crystalline nature, size, and surface potential. The heterogeneous catalytic performance of CeO₂ NPs has been accomplished for the reduction of 2-nitroaniline from the aqueous media. The CeO₂ nanocatalyst displayed excellent reusability, while the reduction in several repetitive catalytic cycles against 2-nitroaniline under optimized conditions. The CeO₂ nanocatalyst shows 99.12% efficiency within 60s reaction time under a greener source of microwave radiation.

Bismuth molybdate incorporated functionalized carbon nanofiber as an electrocatalytic tool for the pinpoint detection of organic pollutant in life samples

Herein, we fabricated a feasible and accurate sensing platform for the quantification of toxic organic pollutant 2-nitroaniline (2-NA) in water samples through electrocatalyst made up of bismuth molybdate (Bi₂MoO₆, BMO) functionalized carbon nanofiber (f-CNF) modified electrode. The preparation of BMO/f-CNF composite is of two methods, such as co-precipitation (C-BMO/f-CNF) and ultrasonication method (U-BMO/f-CNF). The physicochemical properties of the composites were characterized by XRD, FTIR, Raman, BET, FE-SEM, and HR-TEM techniques. At U-BMO/f-CNF, the charge transfer resistance was low (R_ct = 12.47 Ω) compared to C-BMO/f-CNF because nanosized U-BMO particles correctly aim at the defective sites of the f-CNF surface wall. Further, the electrocatalytic activity of C&U-BMO/f-CNF composites was examined by cyclic voltammetry (CV) and differential pulse voltammetry techniques (DPV) for the electrochemical detection of 2-nitroaniline (2-NA). The U-BMO/f-CNF/GCE shows a higher cathodic current, wide dynamic linear range of 0.01-168.01 µM, and superior electrocatalytic activity with a low detection limit (0.0437 µM) and good sensitivity (0.6857 μA μM^-1 cm^-2). The excellent selectivity nature of U-BMO/f-CNF/GCE was observed in the presence of various organic pollutants and a few toxic metal cations. The practical applicability such as stability, repeatability towards 2-NA outcomes with accepted results. Besides, the practical viability of as proposed U-BMO/f-CNF sensor was investigated in soil and lake water samples delivers good recovery results. Hence from these analyses, we conclude that U-BMO/f-CNF/GCE potential for the determination of hazardous environmental pollutant 2-NA.

Metal-Organic Frameworks of MIL-100(Fe, Cr) and MIL-101(Cr) for Aromatic Amines Adsorption from Aqueous Solutions

MIL-100(Fe, Cr) and MIL-101(Cr) were synthesized by the hydrothermal method and applied to the adsorptions of five aromatic amines from aqueous solutions. These three metal-organic frameworks (MOFs) were well characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA) and surface area analysis. The adsorption mechanism of three MOFs and the effects of the structures of MOFs on the adsorption of aromatic amines were discussed. The results show that the cavity system and suitable hydrogen bond acceptor were important factors for the adsorption for five aromatic amines of aniline, 1-naphthalamine, o-toluidine, 2-amino-4-nitrotoluene and 2-nitroaniline: (a) the saturated adsorption capacity of aniline, 1-naphthylamine and o-toluidine on MIL-100(Fe) were 52.0, 53.4 and 49.6 mg/g, respectively, which can be attributed to the intermolecular hydrogen bond interaction and cavity system diffusion. (b) The adsorption capacity of 2-nitroaniline and 2-amino-4-nitrotoluene on MIL-101(Cr) were 54.3 and 25.0 mg/g, respectively, which can be attributed to the more suitable pore size of MIL-101(Cr) than that of MIL-100(Fe, Cr). The MOFs of MIL-100(Fe) and MIL-101(Cr) can be potential materials for removing aromatic amines from aqueous solutions.

Catalytic reduction of 2-nitroaniline: a review

2-nitroaniline (2-NA) is highly toxic and environmental contaminant. It is reduced to less toxic and environmental benign product o-phenylenediamine by using different reducing agents like sodium borohydride, potassium borohydride, or hydrazine hydrate in the presence of various catalytic systems. These catalytic systems have various advantages and drawbacks. Silica-supported gold nanoparticles are frequently reported catalyst for the reduction of 2-nitroaniline in aqueous medium. In this review article, different catalytic systems reported for reduction of o-nitroaniline under various reaction conditions have been discussed. The critical review of the recent research progress for development of novel catalysts used for the reduction of 2-nitroaniline has been provided here.