A simple FRET system using two‐color CdTe quantum dots assisted by cetyltrimethylammonium bromide and its application to Hg(II) detection

In this study, we developed a novel simple fluorescence resonance‐energy transfer (FRET) system between two‐color CdTe quantum dots (QDs) assisted by cetyltrimethylammonium bromide (CTAB). Mercaptopropionic (MPA)‐capped CdTe QDs serving as both donors and acceptors were successfully synthesized by changing the refluxing time in aqueous solution. CTAB micelles formed in water and minimized the distance between the donors and acceptors significantly by electrostatic interactions, improving FRET efficiency. Several factors that affected the fluorescence spectra of the FRET system were investigated. The prepared FRET system was feasible as an effective fluorescent probe to detect Hg(II) in aqueous solution. At pH 7.0, a linear relationship between the quenched fluorescence intensity of orange‐emitting acceptors (QDs_(A)) and Hg(II) concentration was acquired in the range 5–250 nmol/L with a detection limit of 1.95 nmol/L. The developed method showed excellent analytical performance for Hg(II) with high sensitivity and acceptable selectivity, reproducibility and stability. This finding indicated that the method has a promising potential application for environmental monitoring. This study demonstrated the great promise of QDs for expedient, low‐cost and high‐sensitivity detection of Hg(II).     

Determination of oxytetracycline hydrochloride in milk and egg white samples using Ru(bipy)32+–Ce(SO4)2 chemiluminescence

A novel, rapid and sensitive chemiluminescence (CL) method for the determination of oxytetracycline hydrochloride (OTCH) is described in this paper. The presented method was based on the fact that OTCH could immensely enhance the CL of the reaction of cerium sulfate and tris(2,2‐bipyridyl) ruthenium (II) in acidic medium. Under optimal experimental conditions, CL intensity was favorably linear for OTCH in the range 5.0 × 10^?7 to 5.0 × 10^?5 g/ml, with a detection limit of 1.5 × 10^?7 g/ml (S/N = 3). The relative standard detection was 4.76% for 5.0 × 10^?6 g/ml (n = 11). This method was successfully applied to the analysis of OTCH in milk and egg white samples. According to the results of the kinetic curves for OTCH in the Ru(bipy)₃²⁺–Ce(SO₄)₂ CL system, together with CL and ultraviolet (UV)–visible spectra, the possible mechanism of the CL reaction is discussed briefly.     

Interaction of cobalt(II) and copper(II) hydroxamates with polyriboadenylic acid: An insight into RNA based drug designing

The polyadenylic acid [poly(A)] tail of mRNA plays a noteworthy role in the initiation of the translation, maturation, and stability of mRNA. It also significantly contributes to the production of alternate proteins in eukaryotic cells. Hence, it has recently been recognized as a prospective drug target. Binding affinity of bis(N-p-tolylbenzohydroxamato)Cobalt(II), [N-p-TBHA-Co(II)] (1) and bis(N-p-naphthylbenzohydroxamato)Copper(II), [N-p-NBHA-Cu(II)] (2) complexes with poly(A) have been investigated by biophysical techniques namely, absorption spectroscopy, fluorescence spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, circular dichroism spectroscopy, viscometric measurements and through molecular docking studies. The intrinsic binding constants (K_b) of complexes were determined following the order of N-p-TBHA-Co(II)] > N-p-NBHA-Cu(II), along with hyperchromism and a bathochromic shift for both complexes. The fluorescence quenching method revealed an interaction between poly(A)-N-p-TBHA-Co(II)/poly(A)-N-p-NBHA-Cu(II). The mode of binding was also determined via the fluorescence ferrocyanide quenching method. The increase in the viscosity of poly(A) that occurred from increasing the concentration of the N-p-TBHA-Co(II)/N-p-NBHA-Cu(II) complex was scrutinized. The characteristics of the interaction site of poly(A) with N-p-TBHA-Co(II)/N-p-NBHA-Cu(II) were adenine and phosphate groups, as revealed by DRS-FTIR spectroscopy. Based on these observations, a partial intercalative mode of the binding of poly(A) has been proposed for both complexes. Circular dichroism confirmed the interaction of both the complexes with poly(A). The molecular docking results illustrated that complexes strongly interact with poly(A) via the relative binding energies of the docked structure as ?259.39eV and ?226.30eV for N-p-TBHA-Co(II) and N-p-NBHA-Cu(II) respectively. Moreover, the binding affinity of N-p-TBHA-Co(II) is higher in all aspects than N-p-NBHA-Cu(II) for poly(A).     

A novel fluorescent sensor based on electrosynthesized benzene sulfonic acid‐doped polypyrrole for determination of Pb(II) and Cu(II)

To develop conducting organic polymers (COPs) as luminescent sensors for determination of toxic heavy metals, a new benzene sulfonic acid‐doped polypyrrole (PPy‐BSA) thin film was electrochemically prepared by cyclic voltammetry (CV) on flexible indium tin oxide (ITO) electrode in aqueous solution. PPy‐BSA film was characterized by FTIR spectrometry, X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The optical properties of PPy‐BSA were investigated by ultraviolet (UV)‐visible absorption and fluorescence spectrometry in dimethylsulfoxide (DMSO) diluted solutions. PPy‐BSA fluorescence spectra were strongly quenched upon increasing copper(II) ion (Cu²⁺) and lead(II) ion (Pb²⁺) concentrations in aqueous medium, and linear Stern–Volmer relationships were obtained, which indicated the existence of a main dynamic fluorescence quenching mechanism. BSA‐PPy sensor showed a high sensitivity for detection of both metallic ions, Cu²⁺ and Pb²⁺, with very low limit of detection values of 3.1 and 18.0 nM, respectively. The proposed quenching‐fluorimetric sensor might be applied to the determination of traces of toxic heavy metallic ions in water samples.     

Photoluminescence imaging of europium (III)‐doped γ‐Al2O3 nanofiber structures

Aluminium oxide (Al₂O₃) has widely been used for catalysts, insulators, and composite materials for diverse applications. Herein, we demonstrated if γ‐Al₂O₃ was useful as a luminescence support material for europium (Eu) (III) activator ion. The hydrothermal method and post‐thermal treatment at 800°C were employed to synthesize Eu(III)‐doped γ‐Al₂O₃ nanofibre structures. Luminescence characteristics of Eu(III) ions in Al₂O₃ matrix were fully understood by taking 2D and 3D‐photoluminescence imaging profiles. Various sharp emissions between 580 to 720 nm were assigned to the ⁵D₀→⁷F_J (J = 0, 1, 2, 3, 4) transitions of Eu(III) activators. On the basis of X‐ray diffraction crystallography, Auger elemental mapping and the asymmetry ratio, Eu(III) ions were found to be well doped into the γ‐Al₂O₃ matrix at a low (1 mol%) doping level. A broad emission at 460 nm was substantially increased upon higher (2 mol%) Eu(III) doping due to defect creation. The first 3D photoluminescence imaging profiles highlight detailed understanding of emission characteristics of Eu(III) ions in Al oxide‐based phosphor materials and their potential applications.     

Basal and Foliar Treatment using an Organic Fertilizer Amendment Lowers Cadmium Availability in Soil and Cadmium Uptake by Rice on Field Micro-Plot Experiment Planted in Contaminated Acidic Paddy Soil

In the present study, field micro-plot experiments were conducted to investigate the basal and foliar application of a tested organic fertilizer amendment (OFA) for decreasing the risk of Cd accumulating in rice. The results showed that applications of OFA significantly increased rice yields in Cd-polluted soil and reduced the level of Cd in rice plants, especially in rice grain. In addition, three application methods of OFA were investigated (single basal application (B1, B2, and B3), combined basal application (+LM, +D, and +Z), and foliar application (F1, F2)). Treat B, F, +LM, +D were all higher than control on rice yield with 25.03, 28.05, 30.61, 22.50 g pot^?1 on average, respectively. Among which, rice cadmium depress to 0.33 mg kg^?1 in foliar application is considered to be a more efficient and economical method of heavy metal remediation. The mechanism of foliar application to alleviate the accumulation of Cd in brown rice may be related to the probable Cd sequestration in the leaves and straws. And the doses of the foliar application were 2.25–3.75 kg hm^?2, approximately 1.0–2.5% of the basal application amount yet with more effect (0.10 mg kg^?1 more than single basal; 0.23 mg kg^?1 more than combined basal) on Cd reduction.     

Atypical GATA protein TRPS1 plays indispensable roles in mouse two-cell embryo

Zygotic genome activation (ZGA) is one of the most critical events at the beginning of mammalian preimplantation embryo development (PED). The mechanisms underlying mouse ZGA remain unclear although it has been widely studied. In the present study, we identified that tricho-rhino-phalangeal syndrome 1 (TRPS1), an atypical GATA family member, is an important factor for ZGA in mouse PED. We found that the Trps1 mRNA level peaked at the one-cell stage while TRPS1 protein did so at the two/four-cell stage. Knockdown of Trps1 by the microinjection of Trps1 siRNA reduced the developmental rate of mouse preimplantation embryos by approximately 30%, and increased the expression of ZGA marker genes MuERV-L and Zscan4d via suppressing the expression of major histone markers H3K4me3 and H3K27me3. Furthermore, Trps1 knockdown decreased the expression of Sox2 but increased Oct4 expression. We conclude that TRPS1 may be indispensable for zygotic genome activation during mouse PED.     

Identification of a Specific Translational Machinery via TCTP–EF1A2 Interaction Regulating NF1-associated Tumor Growth by Affinity Purification and Data-independent Mass Spectrometry Acquisition (AP-DIA),

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Highlights

• •AP-DIA/SWATH analysis to identify TCTP-interacting proteins in NF1 tumor cells.
• •A highly specific TCTP–EF1A2 interaction but rather than TCTP–EF1A1 interaction.
• •TCTP–EF1A2 interaction mediating formation of EF1A2-elogation factor complex.
• •TCTP–EF1A2 dependent translation machinery regulating NF1 tumor cell growth.

     

microRNA-222 Attenuates Mitochondrial Dysfunction During Transmissible Gastroenteritis Virus Infection

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Highlights

• •microRNA-222 attenuates TGEV-induced mitochondrial dysfunction.
• •microRNA-222 downregulates THBS1 and CD47.
• •THBS1 is the target of microRNA-222 during TGEV infection.
• •THBS1 and CD47 increase mitochondrial Ca²⁺ level and reduced mitochondrial membrane potential (MMP).