Highly fluorescent nickel based metal organic framework for enhanced sensing of Fe3+ and Cr2O72- ions.

Heavy metal contamination has sparked widespread concern among the populace. The significant issues necessitate the creation of high-performance fluorescent pigments that can identify harmful elements in water. The present study deals with metal organic framework [MOF] based on nickel [Ni-BDC MOF]. The Ni-BDC MOF was prepared by facile solvothermal method using nickel nitrate hexahydrate and terephthalic acid ligand as precursors. The MOF was characterized by various techniques in order to examine the crystal, morphological, structural, composition, thermal and optical properties. The detailed characterizations revealed that the synthesized Ni-BDC MOF are well-crystalline with high purity and possessing 3D rhombohedral microcrystals with rough surface. The MOF demonstrate good luminescence performance and excellent water stability. According to the Stern Volmer plot, the tests set up under optimized conditions demonstrate a linear correlation between the fluorescence intensity and concentration of both ions, i.e. Fe3+, and Cr2O72- ions. The linear range and detection limit for Fe3+ and Cr2O72- were found to be 0-1.4 nM and 0.159 nM, and 0-1 nM and 0.120 nM, respectively. The mechanisms for the selective detection of cations and anions were also explored. The recyclability for the prepared MOF was checked up to five cycles which showed excellent stability with just a slight reduction in efficiency. The constructed sensor was also used to assess the presence of Fe3+ and Cr2O72- ions in actual water samples. The results of the different experiments revealed that the prepared MOF is a good material for detecting Fe3+ and Cr2O72- ions.

Highly photoluminescent and pH sensitive nitrogen doped carbon dots (NCDs) as a fluorescent sensor for the efficient detection of Cr (VI) ions in aqueous media.

Fluorescent carbon dots (CDs) are contemporary class of fluorescent materials that has emerged recently and have gathered increasing attention due to its excellent properties as compared to traditional semiconductor quantum dots. CDs have lucrative benefits of less toxicity, biocompatibility, eco friendliness, tunable fluorescence, high chemical and photostability, effortless synthesis routes and uncomplicated surface modifications and functionalization. In the present work, nitrogen-doped carbon dots (NCDs) were prepared by a facile hydrothermal process using l-ascorbic acid and ethylene diamine as precursors. The as-prepared NCDs were hydrophilic in nature and could remain stable for several weeks. NCDs displayed bright blue fluorescence under UV light irradiation and also exhibited an extensive range of emission spectra in the visible region to infra-red region based upon the excitation wavelength. NCDs possessed quasi-spherical morphology and high density growth. NCDs were further utilized as nanoprobes for the pH sensing and proficient sensitive and selective detection of chromium (VI) ions present in aqueous phase. Under augmented modifications and conditions, the photoluminescence intensity of NCDs against various micromolar concentration of chromium (VI) ions presented a linear relationship, as per Stern-Volmer equation. The calibration curve was found to be linear in the range of 0-4 µM and from the slope of the linear curve, the limit of detection (LOD) was calculated to be 2.598 nM. The Stern-Volmer calibration curve was also plotted against different temperatures, verifying static quenching mechanism. Therefore, the as synthesized NCDs can be successfully demonstrated for the efficient pH sensing and the detection of Cr (VI) ions.

Differential placental gene expression in term pregnancies affected by fetal growth restriction and macrosomia.

INTRODUCTION: Extremes of fetal growth are associated with increased perinatal mortality and morbidity and a higher prevalence of cardiovascular disease, obesity and diabetes in later life. We aimed to identify changes in placental gene expression in pregnancies with evidence of growth dysfunction and candidate genes that may be used to identify abnormal patterns of growth prior to delivery. METHODS: Growth-restricted (n = 4), macrosomic (n = 6) and normal term (n = 5) placentas were selected from a banked series (n = 200) collected immediately after caesarean section. RNA was extracted prior to microarray analysis using Affymetrix HG-U219 arrays to determine variation in gene expression. Genes of interest were confirmed using qRT-PCR. RESULTS: 338 genes in the growth-restricted and 41 genes in the macrosomic group were identified to be significantly dysregulated (>2-fold change; p < 0.05). CPXM2 and CLDN1 were upregulated and TXNDC5 and LRP2 downregulated in fetal growth restriction. In macrosomia, PHLDB2 and CLDN1 were upregulated and LEP and GCH1 were downregulated. DISCUSSION: Dysfunctional growth is associated with differential placental gene expression and affects genes with a whole spectrum of developmental and cellular functions. Better elucidation of these pathways may allow the development of biomarkers to identify growth abnormalities and effective prenatal intervention.