Biosynthesis of Silver Nanoparticles Using Chenopodium ambrosioides

Biosynthesis of silver nanoparticles (AgNPs) was achieved using extract of Chenopodium ambrosioides as a reducer and coating agent at room temperature (25°C). Two molar solutions of AgNO3 (1 mM and 10 mM) and five extract volumes (0.5, 1, 2, 3, and 5 mL) were used to assess quantity, shape, and size of the particles. The UV-Vis spectra gave surface plasmon resonance at 434–436 nm of the NPs synthesized with AgNO3 10 mM and all extract volumes tested, showing a direct relationship between extract volumes and quantity of particles formed. In contrast, the concentration of silver ions was related negatively to particle size. The smallest (4.9 ± 3.4 nm) particles were obtained with 1 mL of extract in AgNO3 10 mM and the larger amount of particles were obtained with 2 mL and 5 mL of extract. TEM study indicated that the particles were polycrystalline and randomly oriented with a silver structure face centered cubic (fcc) and fourier transform infrared spectroscopy (FTIR) indicated that disappearance of the –OH group band after bioreduction evidences its role in reducing silver ions

Biosíntesis de nanopartículas de oro mediante el extracto de Opuntia ficus-indica

El presente trabajo describe una ruta de síntesis eco-amigable para obtener nanopartículas de oro en solución acuosa a temperatura ambiente, usando el extracto de una planta endémica de México (Opuntia ficus indica). Las mediciones con espectroscopia UV-Vis de la solución acuosas de ion Au+3 después de entrar en contacto con diferentes volúmenes del extracto Opuntia ficus indica mostraron una intensa banda de absorción alrededor de 540 nm, característica del plasmon de resonancia de nanopartículas de oro. Se ha observado un incremento en la intensidad de dicha banda en función del tiempo, hasta alcanzar un máximo después de 24 horas de reacción. Estudios de TEM, muestran que el extracto de Opuntia ficus indica favorece la formación y estabilización de nanopartículas esféricas con un tamaño promedio de 40 ± 17 nm. Se observa también que los parámetros que controlan el tamaño y la forma de la nanopartículas de oro, son la concentración de iones Au+3 en la solución precursora y el tiempo de reducción, aunque el volumen de agente reductor empleado es el parámetro que ejerce una mayor influencia sobre las características de las nanopartículas de oro

Citric Acid Modifies Surface Properties Of Commercial Ceo2 Nanoparticles Reducing Their Toxicity And Cerium Uptake In Radish (Raphanus Sativus) Seedlings

Little is known about the mobility, reactivity, and toxicity to plants of coated engineered nanoparticles (ENPs). Surface modification may change the interaction of ENPs with living organisms. This report describes surface changes in commercial CeO2 NPs coated with citric acid (CA) at molar ratios of 1:2, 1:3, 1:7, and 1:10 CeO2:CA, and their effects on radish (Raphanus sativus) seed germination, cerium and nutrients uptake. All CeO2 NPs and their absorption by radish plants were characterized by TEM, DLS, and ICP-OES. Radish seeds were germinated in pristine and CA coated CeO2 NPs suspensions at 50 mg/L, 100 mg/L, and 200 mg/L. Deionized water and CA at 100 mg/L were used as controls. Results showed ζ potential values of 21.6 mV and −56 mV for the pristine and CA coated CeO2 NPs, respectively. TEM images showed denser layers surrounding the CeO2 NPs at higher CA concentrations, as well as better distribution and smaller particle sizes. None of the treatments affected seed germination. However, at 200 mg/L the CA coated NPs at 1:7 ratio produced significantly (p ≤ 0.05) more root biomass, increased water content and reduced by 94% the Ce uptake, compared to bare NPs. This suggests that CA coating decrease CeO2 NPs toxicity to plants

Silver nanoparticles biosynthesized using Opuntia ficus aqueous extract

"Silver nanoparticles were synthesized using a green chemistry method. Stable silver nanoparticles in a colloidal aqueous solution were prepared successfully by the chemical reaction of silver nitrate (AgNO3) and Opuntia ficus indica aqueous extract, use

Ether gas-sensor based on Au nanoparticles-decorated ZnO microstructures

An ether gas-sensor was fabricated based on gold nanoparticles (Au-NPs) decorated zinc oxide microstructures (ZnO-MS). Scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM) measurements were performed to study morphological and structural properties, respectively, of the ZnO-MS. The gas sensing response was evaluated in a relatively low temperature regime, which ranged between 150 and 250 °C. Compared with a sensor fabricated from pure ZnO-MS, the sensor based on Au-NPs decorated ZnO-MS showed much better ether gas response at the highest working temperature. In fact, pure ZnO-MS based sensor only showed a weak sensitivity of about 25%. The improvement of the ether gas response for sensor fabricated with Au-NPs decorated ZnO-MS was attributed to the catalytic activity of the Au-NPs. Keywords: ZnO microstructures, Au nanoparticles, Ether, Gas senso

SiO2/polyvinylimidazole hybrid polymer as a sorbent for extraction by matrix solid-phase dispersion (MSPD): synthesis, characterization, and evaluation

Artículo especializado en revista indexadaA novel hybrid polymer was developed and evaluated as a sorbent for the matrix solid-phase dispersion (MSPD) extraction of pesticides. The hybrid polymer was synthesized by the sol–gel method and by free radical polymerization. The chemical structure of the resulting hybrid polymer (SiO2–PVI) was confirmed by Fourier transform infrared spectroscopy (FTIR). Thermal analyses suggest that the polymer consists of an organic/inorganic ratio of 28:72 wt/wt%. Scanning electron microscopy (SEM) and elemental analysis (EDS) revealed particle aggregates and a rough surface and suggested that the polymer is primarily composed of SiO2. The obtained pore size was appropriate for use in a solid-phase extraction support. X-ray photoelectron spectroscopy (XPS) was used to assess the surface composition of the hybrid polymer and indicated the presence of C, N, O, and Si. The material was tested for extraction of five selected organophosphorus pesticides (OPPs) in propolis using gas chromatography–mass spectrometry (GC/MS). In experiments performed in triplicate at 1.0 μg mL−1, pesticide recovery was in the range of 81–122%. In addition, the sorbent hybrid polymer (SiO2–PVI) demonstrated good repeatability (RSD≤11 %), on the same order as C18 (commercial sorbent) when tested under the same conditions. These results suggest that SiO2–PVI hybrid polymer is a good sorptive material that is comparable to the commercially utilized C18 and can be used in MSPD for the extraction of organophosphorus pesticidesCONACyT (83390

Plasmonic Sensing of Aqueous-Divalent Metal Ions by Biogenic Gold Nanoparticles

The chemical interaction between biogenic gold nanoparticles (AuNPs) and several metal (II) ions can be regarded as a practical, twofold, colorimetric, and plasmon resonance sensing method for the recognition of some divalent metal ions in aqueous solutions. The green synthesized AuNPs, using Camellia sinensis as a reducing agent, were characterized by a surface plasmon resonance (SPR) using UV-Vis spectroscopy, infrared spectroscopy, and transmission electron microscopy. The AuNP colloidal solutions obtained have a pink-reddish color with SPRs centered between 529 and 536 nm. AuNPs with spherical, triangular, and hexagonal shapes were found by TEM analyses. Despite their divergent morphologies, these AuNPs can be employed as colorimetric and plasmon resonance sensors for detection of Ca2+, Sr2+, Cu2+, and Zn2+, primarily, in aqueous solutions. Sensibility studies based on molar concentrations were also performed for these metal ions. Furthermore, solid biogenic AuNPs/cellulosic biocomposites were prepared with the aim of developing portable, fast, and dependable colorimetric sensors; nevertheless, these biocomposites resulted to be good adsorbent materials of metal ions

Study of the Morphology of ZnS Thin Films Deposited on Different Substrates Via Chemical Bath Deposition

ARTICULO DE INVESTIGACIÓN EN REVISTA INDEXADAIn this work, the influence of substrate on the morphology of ZnS thin films by chemical bath deposition is studied. The materials used were zinc acetate, tri-sodium citrate, thiourea, and ammonium hydroxide/ammonium chloride solution. The growth of ZnS thin films on different substrates showed a large variation on the surface, presenting a poor growth on SiO2 and HfO2 substrates. The thin films on ITO substrate presented a uniform and compact growth without pinholes. The optical properties showed a transmittance of about 85% in the visible range of 300–800 nm with band gap of 3.7 eV.DGAPA-PAPIIT IN108613-2 projec