scholarly journals Diatom Mediated Production of Fluorescent Flower Shaped Silver-Silica Nanohybrid

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7284
Author(s):  
Piya Roychoudhury ◽  
Aleksandra Golubeva ◽  
Przemysław Dąbek ◽  
Michał Gloc ◽  
Renata Dobrucka ◽  
...  
Keyword(s):  
High Surface ◽  
Nitrate Solution ◽  
Volume Ratio ◽  
Cost Effective ◽  
Silver Nitrate Solution ◽  
Hybrid Nanoparticles ◽  
Sem Images ◽  
Light Region ◽  
Vis Spectroscopy ◽  
Sio2 Particles

Fabrication of flower-like nanostructures are gaining attention because of their high surface/volume ratio and extensive adsorption capacity. In the present investigation, flower-shaped, autofluorescent silver-silica (Ag-SiO2) hybrid nanoparticles have been fabricated exploiting diatoms as a source of nanosilica. Two different species of Gedaniella including G. flavovirens and G. mutabilis showed their efficacy in synthesizing fluorescent Ag-SiO2 nanoflowers (NFs) and nanospheres (NSs) against 9 mM silver nitrate solution, respectively. The biogenic nanoconjugate (Ag-SiO2) was characterized by Uv-vis spectroscopy, energy dispersive X-ray spectroscopy (EDS), scanning (SEM) and transmission (TEM) electron microscopy. Production of Ag-SiO2 hybrid nanoparticle was confirmed by observing both Ag and Si signals from a single nanoparticle in an EDS study. The broad and single absorption band at ~420 nm in Uv-vis spectroscopy confirmed proper miscibility and production of hybrid nanoparticles. The Ag-SiO2 nanohybrids revealed autofluorescent property under the blue light region (excitation ~450–490 nm). SEM images of particles synthesized by G. flavovirens revealed the production of microscopic flower shaped Ag-SiO2 particles with several layers of petals. A TEM study confirmed that the synthesized Ag-SiO2 NFs are variable in size with 100–500 nm in diameter. Decolorization of methylene blue after exposure to Ag-SiO2 particles confirmed catalytic activity of synthesized nanostructures. This eco-friendly method provides a new dimension in nanobiotechnology for biogenesis of such hierarchical nanostructure in a cost-effective way.

scholarly journals CoFe2O4-TiO2Hybrid Nanomaterials: Synthesis Approaches Based on the Oil-in-Water Microemulsion Reaction Method

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Arturo Adrián Rodríguez-Rodríguez ◽  
Sagrario Martínez-Montemayor ◽  
César Cutberto Leyva-Porras ◽  
Francisco Enrique Longoria-Rodríguez ◽  
Eduardo Martínez-Guerra ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Core ◽  
Hybrid Nanoparticles ◽  
Magnetic Domains ◽  
Spinel Type ◽  
Reaction Method ◽  
Light Region ◽  
Oil In Water ◽  
Vis Spectroscopy ◽  
Nanomaterials Synthesis

CoFe2O4nanoparticles decorated and wrapped with TiO2nanoparticles have been prepared by mixing well-dispersed CoFe2O4with amorphous TiO2(impregnation approach) and growing amorphous TiO2over the magnetic core (seed approach), respectively, followed by thermal treatment to achieve TiO2crystallinity. Synthesis strategies were based on the oil-in-water microemulsion reaction method. Thermally treated nanomaterials were characterized in terms of structure, morphology, and composition, to confirm hybrid nanoparticles formation and relate with the synthesis approaches; textural, optical, and magnetic properties were evaluated. X-ray diffraction revealed coexistence of cubic spinel-type CoFe2O4and tetragonal anatase TiO2. Electron microscopy images depicted crystalline nanoparticles (sizes below 25 nm), with homogeneous Ti distribution for the hybrid nanoparticles synthesized by seed approach. EDX microanalysis and ICP-AES corroborated established chemical composition. XPS evidenced chemical states, as well as TiO2predominance over CoFe2O4surface. According to BET measurements, the hybrid nanoparticles were mesoporous. UV-Vis spectroscopy showed optical response along the UV-visible light region. Magnetic properties suggested the breaking order of magnetic domains due to modification with TiO2, especially for mediated seed approach sample. The properties of the obtained hybrid nanoparticles were different in comparison with its individual components. The results highlight the usefulness of designed microemulsion approaches for the straightforward synthesis of CoFe2O4-TiO2nanostructured hybrids.

Cascade catalysis of highly active bimetallic Au/Pd nanoclusters: structure–function relationship investigation using anomalous small-angle X-ray scattering and UV–Vis spectroscopy

2013 ◽  
Vol 46 (5) ◽  
pp. 1353-1360 ◽  
Author(s):  
Sylvio Haas ◽  
Robert Fenger ◽  
Edoardo Fertitta ◽  
Klaus Rademann
Keyword(s):  
Catalytic Activity ◽  
Structural Characteristics ◽  
High Surface ◽  
Volume Ratio ◽  
Single Type ◽  
High Catalytic Activity ◽  
Highly Active ◽  
Bimetallic Nanoclusters ◽  
Vis Spectroscopy ◽  
Cascade Catalysis

Recently, a so-called `crown-jewel' concept of preparation of Au/Pd-based colloidal nanoclusters has been reported [Zhang, Watanabe, Okumura, Haruta & Toshima (2011).Nat. Mater.11, 49–52]. Here, a different way of preparing highly active Au/Pd-based nanoclusters is presented. The origin of the increased activity of Au/Pd-based colloidal bimetallic nanoclusters was unclear up to now. However, it is, in general, accepted that in the nanometre range (1–100 nm) the cluster size, shape and composition affect the structural characteristics (e.g.lattice symmetry, unit cell), electronic properties (e.g.band gap) and chemical properties (e.g.catalytic activity) of a material. Hence, a detailed study of the relationship between the nanostructure of nanoclusters and their catalytic activity is presented here. The results indicate that a high surface-to-volume ratio of the nanoclusters combined with the presence of `both' Au and Pd isolated regions at the surface are crucial to achieve a high catalytic activity. A detailed structure elucidation directly leads to a mechanistic proposal, which indeed explains the higher catalytic activity of Au/Pd-based catalysts compared with pure metallic Au or Pd. The mechanism is based on cascade catalysis induced by a single type of nanoparticle with an intermixed surface of Au and Pd.

Electrochemically Deposited Aluminum in Template of Porous Silicon Film

2010 ◽  
Vol 663-665 ◽  
pp. 1032-1035
Author(s):  
Bao Gai Zhai ◽  
Qing Lan Ma ◽  
Ming Meng ◽  
Yuan Ming Huang
Keyword(s):  
Porous Silicon ◽  
Electrochemical Deposition ◽  
High Surface ◽  
Silicon Film ◽  
Volume Ratio ◽  
Deposition Condition ◽  
Sem Images ◽  
Interesting Phenomenon ◽  
Electrochemically Deposited ◽  
The One

In this article, we report on the observations that in the aqueous electrolyte of aluminum nitrate, the thin metallic conducting films on both internal and external surface of porous silicon (PS) thin films that emit visible photoluminescence at room temperature prior to electrochemical deposition have been obtained under electrochemical deposition condition. Add to this high surface-to-volume ratio and these make it a good candidate for the catalyst supporter. We have investigated the surface morphology of PS after the interval of about 30 hours of electrochemically deposited aluminum by means of scanning electron microscopy (SEM). It has been shown from SEM images that not only micrometer-sized pores are smoothed by deposition of aluminum microcrystal, but also the presences of semi-sphere aluminum microcrystal which rooted in the tip of micrometer-sized pores are observed. On the one hand, this extremely interesting phenomenon which the micrometer-sized pores are smoothed may be explained in terms of principle of electrochemical deposition; on the other hand, we have laid the formation mechanism of semi-spherical aluminum microcrystal at the door of Gibbs free energy.

Adsorption potential of nanocomposites for the removal of toxins in healthcare

2020 ◽  
Vol 16 ◽  
Author(s):  
Pravin Shende ◽  
Nikita P. Devlekar
Keyword(s):  
Heavy Metals ◽  
Human Health ◽  
Industrial Wastewater ◽  
Biological Systems ◽  
High Surface ◽  
Volume Ratio ◽  
Cost Effective ◽  
Isotherm Models ◽  
Potential Applications ◽  
Enhanced Adsorption

: Industrial wastewater is one of the by-products of several industries and it consists of water that requires treatment before it is discharged in water bodies. The presence of toxins in wastewater such as dyes and heavy metals is hazardous to human health and requires effective removal to reduce environmental pollution. Industrial wastewater treatment has become a global concern in healthcare and environment leading to the development of various technologies for the removal of toxins from wastewater. Various processes and technologies such as advanced oxidation processes, adsorption and membrane technology show potential in treating industrial wastewater. Another source of toxins in the form of pesticides is harmful to human health leading to severe health problems. Nanocomposites show potential as efficient adsorbents for the removal of toxins owing to the enhanced adsorption capacity, promising physicochemical properties and high surface-to-volume ratio due to nanoscale dimension. Nanocomposites are cost effective and efficient nanoadsorbents for the removal of various toxins. This review focuses on the potential applications of nanocomposites as adsorbents for the removal of toxins like dyes, heavy metals and pesticides from wastewater and biological systems. The use of nanocomposites as efficient adsorbents in the removal of toxins, various isotherm models and adsorption kinetics applied in the mechanism of adsorption are also discussed in the article. In the near future, nanocomposites may provide a simple, economical and efficient adsorption system for the removal of toxins from wastewater and biological systems.

Synthesis of Biocompatible Silver Nanoparticles and Nanotoxicity in Aquatic Ecosystems

MRS Advances ◽  
2020 ◽  
Vol 5 (16) ◽  
pp. 805-813
Author(s):  
Jousen A. Merced-Colón ◽  
David Medina-Suarez ◽  
Gabriela M. Mercado-Guzmán ◽  
Sonia J. Bailón
Keyword(s):  
Silver Nanoparticles ◽  
Aquatic Ecosystems ◽  
Negative Refraction ◽  
High Surface ◽  
Volume Ratio ◽  
Aquatic Organisms ◽  
Artemia Salina ◽  
Ag Nps ◽  
Spherical Form ◽  
Vis Spectroscopy

ABSTRACTSilver nanoparticles (Ag NPs) have unique optical, electrical, and thermal properties and are being incorporated into products that range from photovoltaics to biological and chemical sensors. The production of silver nanoparticles has been increasing worldwide in the nanotechnology industry due to the variety of applications and are very likely to reach aquatic ecosystems damaging them. Due to their small size and high surface area to volume ratio of NPs, they can strongly interact with life cells and cause damage to tested animals. Based on the mentioned previously, it is necessary to evaluate the silver nanoparticle nanotoxicity in aquatic ecosystems to prevent possible ingestion or transfer to humans. Also, the research will benefit aquatic systems due to less pollution around aquatic organisms. The objectives of this research included: i) production and characterization of stable silver nanoparticles in water, ii) characterizing the optical properties by UV-Vis spectroscopy and morphology by HR-TEM and; iii) evaluate the toxicity of silver nanoparticles in aquatic organisms, i.e Artemia salina. Results obtained evidenced that Ag NPs showed an intense absorption peak at 448 nm. This broad peak is due to the phenomenon called surface plasmon resonance (SPR) that is responsible for a variety of phenomena, including nanoscale optical focusing, negative refraction, and surface-enhanced Raman scattering. HR-TEM measurements evidenced the spherical form of the nanoparticles and its small size at around 12-20 nm. In addition, Electron Diffraction analyses suggested the composition of the nanoparticle, which contained only Ag0. The toxicity assays were evaluated using different concentrations of purified Ag NPs. During the cytotoxicity assay, it was demonstrated that Ag NPs were not toxic to Artemia salina after 24 and 48 hours of exposure. However, silver (as silver nitrate) evidenced high toxicity to Artemia salina at larval stage.

Nanocrystalline BaTiO3 from freeze-dried nitrate solutions

1996 ◽  
Vol 11 (5) ◽  
pp. 1199-1209 ◽  
Author(s):  
J. M. McHale ◽  
P. C. McIntyre ◽  
K. E. Sickafus ◽  
N. V. Coppa
Keyword(s):  
Particle Size ◽  
Calcination Temperature ◽  
High Surface ◽  
Nitrate Solution ◽  
Average Particle Size ◽  
Volume Ratio ◽  
Product Formation ◽  
Cubic Phase ◽  
Average Particle ◽  
Freeze Dried

An aqueous, all nitrate, solution-based preparation of BaTiO3 is reported here. Rapid freezing of a barium and titanyl nitrate solution, followed by low temperature sublimitation of the solvent, yielded a freeze-dried nitrate precursor which was thermally processed to produce BaTiO3. XRD revealed that 10 min at temperatures ≧600 °C resulted in the formation of phase pure nanocrystalline BaTiO3. TEM revealed that the material was uniform and nanocrystalline (10–15 nm). The high surface to volume ratio inherent in these small particles stabilized the cubic phase of BaTiO3 at room temperature. It was also found that the average particle size of the BaTiO3 produced was highly dependent upon calcination temperature and only slightly dependent upon annealing time. This result suggests a means of selection of particle size of the product through judicious choice of calcination temperature. The experimental details of the freeze-dried precursor preparation, thermal processing of the precursor, product formation, and product morphology are discussed.

scholarly journals Spatiotemporal controlled delivery of nanoparticles to injured vasculature

2010 ◽  
Vol 107 (5) ◽  
pp. 2213-2218 ◽  
Author(s):  
Juliana M. Chan ◽  
Liangfang Zhang ◽  
Rong Tong ◽  
Debuyati Ghosh ◽  
Weiwei Gao ◽  
...  
Keyword(s):  
Drug Release ◽  
High Surface ◽  
Volume Ratio ◽  
Hybrid Nanoparticles ◽  
Phage Library ◽  
Optimal Size ◽  
Systemic Delivery ◽  
Cell Surface Antigens

There are a number of challenges associated with designing nanoparticles for medical applications. We define two challenges here: (i) conventional targeting against up-regulated cell surface antigens is limited by heterogeneity in expression, and (ii) previous studies suggest that the optimal size of nanoparticles designed for systemic delivery is approximately 50–150 nm, yet this size range confers a high surface area-to-volume ratio, which results in fast diffusive drug release. Here, we achieve spatial control by biopanning a phage library to discover materials that target abundant vascular antigens exposed in disease. Next, we achieve temporal control by designing 60-nm hybrid nanoparticles with a lipid shell interface surrounding a polymer core, which is loaded with slow-eluting conjugates of paclitaxel for controlled ester hydrolysis and drug release over approximately 12 days. The nanoparticles inhibited human aortic smooth muscle cell proliferation in vitro and showed greater in vivo vascular retention during percutaneous angioplasty over nontargeted controls. This nanoparticle technology may potentially be used toward the treatment of injured vasculature, a clinical problem of primary importance.

scholarly journals Green Synthesized of Ag/Ag2O Nanoparticles Using Aqueous Leaves Extracts of Phoenix dactylifera L. and Their Azo Dye Photodegradation

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 468
Author(s):  
Salah Eddine Laouini ◽  
Abderrhmane Bouafia ◽  
Alexander V. Soldatov ◽  
Hamed Algarni ◽  
Mohammed Laid Tedjani ◽  
...  
Keyword(s):  
Azo Dye ◽  
Dye Degradation ◽  
Volume Ratio ◽  
Spherical Shape ◽  
Cost Effective ◽  
Phoenix Dactylifera ◽  
Infrared Analysis ◽  
Phoenix Dactylifera L ◽  
Vis Spectroscopy ◽  
Silver Silver

In this study, silver/silver oxide nanoparticles (Ag/Ag2O NPs) were successfully biosynthesized using Phoenix dactylifera L. aqueous leaves extract. The effect of different plant extract/precursor contractions (volume ratio, v/v%) on Ag/Ag2O NP formation, their optical properties, and photocatalytic activity towards azo dye degradation, i.e., Congo red (CR) and methylene blue (MB), were investigated. X-ray diffraction confirmed the crystalline nature of Ag/Ag2O NPs with a crystallite size range from 28 to 39 nm. Scanning electron microscope images showed that the Ag/Ag2O NPs have an oval and spherical shape. UV–vis spectroscopy showed that Ag/Ag2O NPs have a direct bandgap of 2.07–2.86 eV and an indirect bandgap of 1.60–1.76 eV. Fourier transform infrared analysis suggests that the synthesized Ag/Ag2O NPs might be stabilized through the interactions of -OH and C=O groups in the carbohydrates, flavonoids, tannins, and phenolic acids present in Phoenix dactylifera L. Interestingly, the prepared Ag/Ag2O NPs showed high catalytic degradation activity for CR dye. The photocatalytic degradation of the azo dye was monitored spectrophotometrically in a wavelength range of 250–900 nm, and a high decolorization efficiency (84.50%) was obtained after 50 min of reaction. As a result, the use of Phoenix dactylifera L. aqueous leaves extract offers a cost-effective and eco-friendly method.

scholarly journals Comparison of the Ability of Two Brands of CBCT with That of SEM to Detect the Marginal Leakage of Class V Composite Resin Restorations

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Mitra Karbasi Kheir ◽  
Leili Khayam
Keyword(s):  
Composite Resin ◽  
Nitrate Solution ◽  
Silver Nitrate Solution ◽  
Composite Resins ◽  
Rank Test ◽  
Sem Images ◽  
Class V ◽  
Significant Difference ◽  
The Mean ◽  
Composite Resin Restorations

Objectives. This study was carried out to compare the ability of two common brands of cone-beam computed tomography (CBCT), including New Tom and Planmeca, to detect the marginal leakage of class V composite resins. The ability of each of the two brands of CBCT to detect the marginal leakage of class V composite resins was also compared with that of scanning electron microscopy (SEM). Methods. Class V cavities were prepared on the buccal surface of sixteen extracted caries-free human premolars. Cavities were conditioned and filled with composite resin. The teeth were immersed in 50% weight/weight aqueous silver nitrate solution for 24 hours. They were then taken out and rinsed with distilled water. Next, they were put in a developing solution. They were first viewed with New Tom and Planmeca CBCT units and were then sectioned and evaluated by an SEM. Results. The results of the Wilcoxon signed-rank test showed no significant difference between the mean marginal leakage scores of New Tom and Planmeca CBCT images ( p value = 0.157) and between those of New Tom CBCT and SEM images ( p value = 0.098). However, there was a significant difference between the mean marginal leakage scores of Planmeca CBCT and SEM images ( p value = 0.023). Conclusion. There were no significant differences between New Tom and Planmeca CBCT units in the detection of marginal leakage of class V composite resins. However, when these CBCT units were compared with the SEM, the New Tom CBCT unit could detect the marginal leakage better than Planmeca.

scholarly journals Silver Flowerlike Structures for Surface-Enhanced Raman Spectroscopy

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3184
Author(s):  
Gitchka G. Tsutsumanova ◽  
Neno D. Todorov ◽  
Stoyan C. Russev ◽  
Miroslav V. Abrashev ◽  
Victor G. Ivanov ◽  
...  
Keyword(s):  
High Surface ◽  
Volume Ratio ◽  
Cost Effective ◽  
Surface Enhanced Raman Spectroscopy ◽  
Aluminum Surface ◽  
Sers Substrate ◽  
Raman Enhancement ◽  
Developed Surface ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

Micro- and nanoflowers are a class of materials composed of particles with high surface-to-volume ratio. They have been extensively studied in the last decade due to simple preparation protocols and promising applications in biosensing, as drug delivery agents, for water purification, and so on. Flowerlike objects, due to their highly irregular surface, may act also as plasmonic materials, providing resonant coupling between optical waves and surface plasmon excitations. This fact allows us to infer the possibility to use micro- and nanoflowers as effective surface-enhanced Raman scattering (SERS) substrate materials. Here, we report on the design and Raman enhancement properties of silver flowerlike structures, deposited on aluminum surface. A simple and cost-effective fabrication method is described, which leads to SERS substrates of high developed surface area. The morphology of the silver flowers on a nanoscale is characterized by self-organized quasiperiodic stacks of nanosheets, which act as plasmonic cavity resonators. The substrates were tested against rhodamine-6G (R6G) water solutions of concentration varying between 10−3 M and 10−7 M. Optimal SERS enhancement factors of up to 105 were established at R6G concentrations in the 10−6–10−7 M range.

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