Search

Biogenic synthesis of gold nanoparticles have been accomplished using dried biomass of two high altitude lichen species, collected from the alpine region of Eastern Himalaya in Arunachal Pradesh state of North East India, without addition of any external reducing or stabilizing chemicals. The nanoparticles were characterised by UV–visible, FT-IR spectroscopy, powder X-ray diffraction (XRD), and transmission electron microscopy (TEM). The as-obtained gold nanoparticles showed surface plasmon resonance (SPR) band at ~535 nm. The XRD study furnished evidence for the formation of face-centered cubic structure of gold nanomaterials. The nanoparticles produced with Acroscyphus sp. consisted of multiply twinned quasi-spherical and prismatic shapes while those accessed with Sticta sp. are exclusively multiply twinned. The biomatrix loaded gold nanomaterial exhibited pronounced antioxidant activity. [ABSTRACT FROM AUTHOR]

Abstract: Biosynthesis of gold nanoparticles has been achieved via reduction of an aqueous chloroauric acid solution with dried biomass of a freshwater epilithic green alga, Prasiola crispa, collected from a high altitude river ecosystem in Arunachal Pradesh state, India. The synthesized nanoparticles were characterized by UV–visible, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR, and DLS studies. The UV–visible spectrum of the synthesized gold nanoparticles showed a surface plasmon resonance (SPR) around 535nm after 12h. The powder XRD pattern furnished evidence for the formation of face-centered cubic structure of gold having average crystallite size 9.8nm. The TEM images showed the nanoparticles to be nearly spherical in shape with sizes in the range of 5–25nm. [Copyright &y& Elsevier]

[Display omitted] • Industrial scale adopted chemical method used for preparation of Sn doped CeO 2. • Sn-CeO 2 /GCE electrode demonstrated as an excellent electrocatalytic oxidation of nitrite (NO 2 –) • The remarkable sensitivities of nitrite found that 245.4 µA cm−2 mM−1 and 89.53 µA cm−2 mM−1. • The limit of detection (LOD) towards nitrite ion sensing was found to be 16 nM. Development of novel electrode materials for sensing water pollutant like nitrite, nitrate, paramedical pollutants and fertilizers is a more promising research area in electrochemical sensor field. Various pure as well as doped metal oxides were used as electrodes for sensing the water pollutants but, deficits in stability, reproducibility and real time analysis. In the present work, a promising Sn-doped CeO 2 based sensor was fabricated for sensing nitrite in water. A selective concentration of Sn (5%) doped CeO 2 nanoparticles were synthesized by facile chemical precipitation method. The structural, optical and morphological information were studied using various techniques. The morphological of the sample was revealed an agglomerated with spherical nanoparticles with size of 8.5 nm. The synergistic effect of Sn-CeO 2 /GCE improves the electrochemical behavior of nitrite on the modified surface. Sn-doped CeO 2 nanoparticles has a better surface property and provides a more fine-grained media to facilitate electron transfer during the reaction between analyte and electrode. The Sn-CeO 2 /GCE electrode possesses excellent electrocatalytic oxidation of nitrite (NO 2 –) which was investigated by cyclic voltammetry (CV) and amperometry techniques. The remarkable sensitivities of nitrite were found that 245.4 µA cm−2 mM−1 and 89.53 µA cm−2 mM−1 with R2 = 0.999 and RSD of ∼ 6%. Similarly, the limit of detection (LOD) towards nitrite ion sensing was found to be 16 nM. The real time application of Sn-CeO 2 /GCE sensor was demonstrated by the detection of nitrite present in environmental water samples with excellent recoveries. Hence, Sn-doped CeO 2 modified electrode also demonstrates good reproducibility, long time stability, and excellent selectivity properties. Thus, a developed electrochemical sensor possesses a novel promise for the construction of simple and sensitive nitrite analytical stage. [ABSTRACT FROM AUTHOR]