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Open Access journal
ISSN (Print) 2190-5509 - ISSN (Online) 2190-5517
Published by SpringerOpen [188 journals]
- Synthesis of ammonium and sulfate ion-functionalized titanium dioxide for
Abstract: Abstract Due to high band gap energy the optimum photocatalytic activities can only be achieved under UV light, thus limiting the practical application of TiO2. In this study, a method combining NH4 +/SO4 2−-functionalization technique and post-treatment was developed and successfully applied to synthesize photoactive TiO2 samples which showed higher photocatalytic activity than the commercial P25 TiO2 under visible light radiation. The results also showed that the addition of (NH4)2SO4 surface functionalization on TiO2 increased the photocatalytic activity, which could be due to the combined effect of crystallinity and band gap energies. Moreover, the results showed that calcination temperature was inversely proportional to photocatalytic activity. The degradation efficiency for methylene blue under visible light was improved by ~2 times from 10.7% for P25 nano Degussa TiO2 to 20.2% for the synthesized sample. The band gap energies were also reduced from 3.7 to 3.4 eV (under UV–Vis direct transition mode) indicating a red shift towards higher wavelength.
- Effects of concentration on CdO films grown by electrodeposition
Abstract: Abstract Thin films of CdO were synthesized by electrodeposition via chronoamperometry. The concentrations of aqueous solutions of Cd(NO3)2 were chosen between 0.005 and 0.08 M. It was thought that the reaction rate would reach saturation at 0.02 M of concentration and it was measured as the concentration increased, the thicknesses of the films increased from the 452 nm to the 798 nm. The well-crystallized film was observed to be at 0.01 M of concentration. It was also found that the band gap increased at low concentrations and surface morphology of the films did not change much with concentration.
- Effect of temperature on the morphology of ZnO nanoparticles: a
Abstract: Abstract The present study reports the comparative analysis for the synthesis of zinc oxide nano particles by precipitation techniques using different zinc precursors. The synthesized nano particles were characterized by X-ray diffractometry (XRD), energy dispersive X-ray analysis and scanning electron microscopy (SEM) analysis for their sizes, shapes and arrangement. SEM has been studied for the samples before as well as after calcination to know the effect of temperature on structural behaviours. The XRD pattern shows the purity of synthesized zinc oxide nano particles and using Debye–Scherrer equation, the average crystal size of synthesized nanoparticles was calculated. The results have been discussed in the light of variation of morphological structures of different samples. Apart from this, the band gap energies of the synthesized particles have also been calculated from UV–visible spectrophotometric analysis, which is quite appreciable with the reported results.
- Sonochemical synthesis of novel magnesium 1,2,4-triazole-1-carbodithioate
nanoparticles as antifungals
Abstract: Abstract Novel magnesium 1,2,4-triazole-1-carbodithioates were sonochemically synthesized as water-dispersable nanoparticles owing to their water insolubility. The two-step reaction protocol was followed to synthesize the novel triazole ligand system for complexation with magnesium metal due to its low biological toxicity. Different concentrations of Poly Vinyl Pyrrolidine were used to stabilize and standardise the size of nanoparticles, which were characterised by TEM analysis. UV–Visible and infrared spectroscopies were used to analyse the metal ligand interaction, and CHNS analysis was used to propose the structure of the metal complex. The spore germination inhibition technique was used to evaluate the antifungal potential of synthesized nano-complexes against two phytopathogenic test fungi viz. A. alternata and F. moniliforme. The nanoparticles had inflicted moderate in vitro inhibition of fungal growth, which was comparable to standard fungicide Indofil M-45. The in silico toxicity of the compounds was made using the Toxtree analysis software that indicated the compounds belong to class III group of toxicity, which was same as that of commercial standards of DTC.
- Preparation and properties of polystyrene incorporated with gold and
silver nanoparticles for optoelectronic applications
Abstract: Abstract In this paper, methyl-orange-doped polystyrene (PS) microspheres covered with gold and silver nanoparticles (NPs) have been synthesized. The optical and structural properties of the porous polystyrene films before and after incorporation of Au and Ag nanoparticles were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), Fourier transformation infrared spectrophotometer (FT-IR), and UV–Vis spectrophotometer. The optical data showed that the optical energy gap of PS film was increased from 2 to 3.4 eV and to 3.5 eV after being filled with Ag and Au nanoparticles, respectively. The electrical and photoresponse properties of Ag–PS/p-Si and Au–PS/p-Si heterojunctions were studied. The rectification characteristics of the junction were improved after nanoparticle incorporation. The photoresponse results confirm the presence of two peaks of response located at 450 and 900 nm. The Au–PS/Si heterojunction gave the best photosensitivity.
- Self-assembled nanotubes from single fluorescent amino acid
Abstract: Abstract Self-assembly of biomolecules has gained increasing attention as it generates various supramolecular structural assemblies having potential applications principally in biomedical sciences. Here, we show that amino acid like tryptophan or tyrosine readily aggregates as nanotubes via a simple self-assembly process. These were characterized by FTIR, scanning electron microscopy, and by fluorescence microscopy. Nanotubes prepared from tryptophan are having ~200 nm inner diameter and those from tyrosine are having the same around ~50 nm diameter.
- Nanoparticle targeting of Gram-positive and Gram-negative bacteria for
magnetic-based separations of bacterial pathogens
Abstract: Abstract Antimicrobial resistance is a healthcare problem of increasing significance, and there is increasing interest in developing new tools to address bacterial infections. Bacteria-targeting nanoparticles hold promise to improve drug efficacy, compliance, and safety. In addition, nanoparticles can also be used for novel applications, such as bacterial imaging or bioseperations. We here present the use of a scalable block-copolymer-directed self-assembly process, Flash NanoPrecipitation, to form zinc(II)-bis(dipicolylamine) modified nanoparticles that bind to both Gram-positive and Gram-negative bacteria with specificity. Particles have tunable surface ligand densities that change particle avidity and binding efficacy. A variety of materials can be encapsulated into the core of the particles, such as optical dyes or iron oxide colloids, to produce imageable and magnetically active bacterial targeting constructs. As a proof-of-concept, these particles are used to bind and separate bacteria from solution in a magnetic column. Magnetic manipulation and separation would translate to a platform for pathogen identification or removal. These magnetic and targeted nanoparticles enable new methods to address bacterial infections.
- A new approach for orientation-controlled growth of CNTs: an in-depth
analysis on the role of oxygen plasma treatment to catalyst
Abstract: Abstract In this paper, a novel and easy technique is proposed for orientation controlled growth of MWNTs. The results indicate that when CNT growth was carried over the substrate, not treated with plasma, horizontal network of MWNTs was formed. Plasma treatment to the substrate prior to CNTs growth led to formation of vertically aligned MWNTs. An in situ growth as a function of plasma treatment time reveals the mechanism behind this flip process. All experiments were performed under atmospheric pressure. At every step during time-dependent growth process, CNTs were characterized using FESEM, HRTEM, and Raman spectroscopy. Iron sputtered silicon substrate was also investigated to validate the excellent formation of as-grown vertical CNTs and also to analyze the role of oxygen plasma behind the orientation-controlled growth. The as-grown CNTs over the iron sputtered silicon substrate with or without plasma treatment were characterized by FESEM and AFM. The successful orientation-controlled growth of CNTs was achieved.
- Formulation and characterization of solid lipid nanoparticles for an
anti-retroviral drug darunavir
Abstract: Abstract Darunavir, an anti-HIV drug having poor solubility in aqueous and lipid medium, illustrates degradation above its melting point, i.e. 74 °C, thus, posing a challenge to dosage formulation. Despite, the drug suffers from poor oral bioavailability (37%) owing to less permeability and being poly-glycoprotein and cyp3A metabolism substrate. The study aimed formulating a SLN system to overcome the formulation and bioavailability associated problems of the drug. Based on the drug solubility and stable dispersion findings, lipid and surfactant were chosen and nanoparticles were prepared using hot-homogenization technique. Optimization of variables such as lipid concentration, oil-surfactant and homogenization cycle was carried and their effect on particle size and entrapment efficiency was studied. Freeze-dried SLN further characterized using SEM, DSC and PXRD analysis revealed complete entrapment of the drug and amorphous nature of the SLN. In vitro pH release studies in 0.1 N HCl and 6.8 pH buffer demonstrated 84 and 80% release at the end of 12th h. The apparent permeability of the SLN across rat intestine was found to be 24 × 10−6 at 37 °C at the end of 30 min while at 4 °C the same was found to be 5.6 × 10−6 prompting involvement of endocytic processes in the uptake of SLN. Accelerated stability studies revealed no prominent changes upon storage.
- Li-ion battery cooling system integrates in nano-fluid environment
Abstract: Abstract In this design challenge by the Texas Space Grant Consortium, the researchers design a cooling system for a lithium-ion battery. Lithium-ion batteries are an effective and reliable source of energy for small, portable devices. However, similar to other existing sources of energy, there is always a problem with overheating. The objective is to design a cooling system for lithium-ion batteries that will work in a zero gravity environment for orbital and interplanetary space systems. The system is to serve as a backup battery and a signal booster that can be incorporated into a spacesuit. The design must be able to effectively cool the batteries without the use of an atmosphere to carry away heat but also be a lightweight and reliable design. The design incorporates carbon nanotubes suspended in distilled water creating a nano-fluid environment. This design must include a failsafe in the event of thermal runaway, a problem common to lithium-ion batteries. This failsafe will completely shut off the system if the batteries reach a certain temperature. A cooling system that incorporates nano-fluids will achieve a lightweight and efficient way of cooling batteries.
- Dispersed gold nanoparticles potentially ruin gold barley yellow dwarf
virus and eliminate virus infectivity hazards
Abstract: Abstract Gold nanoparticles (AuNPs) application melted barley yellow dwarf virus-PAV (BYDV-PAV) spherical nanoparticle capsids. Synergistic therapeutic effects for plant virus resistance were induced by interaction with binding units of prepared AuNPs in a water solution which was characterized and evaluated by zeta sizer, zeta potential and transmission electron microscopy (TEM). The yield of purified nanoparticles of BYDV-PAV was obtained from Hordeum vulgare (Barley) cultivars, local and Giza 121/Justo. It was 0.62 mg/ml from 27.30 g of infected leaves at an A260/A280 ratio. Virus nanoparticle has a spherical shape 30 nm in size by TEM. BYDV-PAV combined with AuNPs to challenge virus function in vivo and in vitro. Dual AuNPs existence in vivo and in vitro affected compacted configuration of viral capsid protein in the interior surface of capsomers, the outer surface, or between the interface of coat protein subunits for 24 and 48 h incubation period in vitro at room temperature. The sizes of AuNPs that had a potentially dramatic deteriorated effect are 3.151 and 31.67 nm with a different intensity of 75.3% for the former and 24.7% for the latter, which enhances optical sensing applications to eliminate virus infectivity. Damages of capsid protein due to AuNPs on the surface of virus subunits caused variable performance in four different types of TEM named puffed, deteriorated and decorated, ruined and vanished. Viral yield showed remarkably high-intensity degree of particle symmetry and uniformity in the local cultivar greater than in Giza 121/Justo cultivar. A high yield of ruined VLPs in the local cultivar than Justo cultivar was noticed. AuNPs indicated complete lysed VLPs and some deteriorated VLPs at 48 h.
- Silver nanoparticles (AgNPs) biosynthesized using pod extract of Cola
nitida enhances antioxidant activity and phytochemical composition of
Amaranthus caudatus Linn
Abstract: Abstract This study investigates the influence of different concentrations of AgNPs biologically synthesized using pod extract of Cola nitida on antioxidant activity, phenolic contents, flavonoid contents and compositions of Amaranthus caudatus L. AgNPs of 25, 50, 75, 100 and 150 ppm were utilized in growing A. caudatus while water was used as control. Delayed germination for two days was observed for A. caudatus grown with 150 ppm of AgNPs, while others showed no difference. There were 43.3, 38.7, 26.7 and 6.48% improvements in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant activity of A. caudatus grown with 25, 50, 75 and 100 ppm of AgNPs, respectively, compared to control. Antioxidant activity of A. caudatus grown with AgNPs reduced with increase in the concentrations of AgNPs. A. caudatus grown with 50 ppm of AgNPs was the most potent with the least IC50 of 0.67 mg/ml. Significant improvements obtained for phenolic and flavonoid contents grown with AgNPs were concentration dependent. Enhancements of 21.9, 68.19, and 1.98% in phenolic contents were achieved in treatments with 25, 50 and 75 ppm AgNPs, respectively, while 32.58, 35.80, and 7.20% improvement in flavonoids were obtained for 25, 50 and 100 ppm treatments, respectively. Kaempferol and quercetin were the most abundant flavonoids in A. caudatus treated with 50 ppm of AgNPs, showing the highest flavonoid composition. This further confirms A. caudatus grown with 50 ppm of AgNPs as the most potent. This study has shown that concentration-dependent AgNPs can be used to boost antioxidant activity and phytochemical contents of vegetables.
- Molybdenum disulfide grafted titania nanotube arrays as high capacity
retention anode material for lithium ion batteries
Abstract: Abstract Titania nanotube arrays (TNAs) were grown by anodic oxidation method, and molybdenum disulfide (MoS2) grafted TNAs have been synthesized via one-step hydrothermal process. The MoS2 grafted TNAs (MoS2/TNAs) when employed as an anode material in lithium ion battery, exhibited excellent areal specific capacity (~430 µAh cm−2) at current density of 50 µA cm−2, which is 33% higher as compared to the pure anatase TNAs and 55% higher as compared to MoS2. Moreover, the capacity loss per cycle of MoS2/TNAs (~0.21%) was significantly lower than anatase TNAs (~1.47%), suggesting an increase of capacity retention.
- Carbon nanotube nanocomposite-modified paper electrodes for supercapacitor
Abstract: Abstract This paper describes the evaluation of carbon paper electrodes for supercapacitor applications. The electrodes are based on carbon micro-fiber paper modified with active material consisting of layers of silver nano-particulate ink and a nanocomposite of multi-walled carbon nanotubes and silver nano-particulate ink. The electrodes were characterized microscopically and electrically. Current–voltage studies revealed a consistent Ohmic behavior of the electrode when modified with different nanostructured active material. Among the active materials incorporated into the electrode, a nanocomposite of carbon nanotubes and silver nano-particulate ink significantly improved capacitance. The paper electrodes can be used for lightweight and ultrathin supercapacitors and other portable energy applications.
- Preparation and characteristics study of nano-porous silicon UV
Abstract: Abstract In this study, influence of rapid thermal oxidation RTO and embedding of gold nanoparticles on the performance of porous silicon photodetector synthesised by anodization technique were investigated. Anodization technique was used to fabricate porous silicon photodetector at 10 mA/cm2 for 10 min. The structural, morphological, and photoluminescence properties of porous silicon and gold nanoparticles were investigated. Dark and illuminated current–voltage I–V characteristics, linearity, spectral responsivity, detectivity, and pulsed responsivity of photodetector were investigated before and after RTO and after incorporation of gold nanoparticles. The photosensitivity of nano-porous silicon photodetector at 365 nm was increased from 44 to 154 mA/W and to 200 mA/W at 10 V bias after RTO process and incorporating the gold nanoparticles into the silicon matrix, respectively.
- A study on the effect of chemically synthesized magnetite nanoparticles on
earthworm: Eudrilus eugeniae
Abstract: Abstract Most look into the benefits of the nanoparticles, but keeping aside the benefits; this study focuses on the impacts of nanoparticles on living systems. Improper disposal of nanoparticles into the environment is a subject of pollution or nano-pollution which in turn affects the flora and fauna in the ecosystem, particularly soil ecosystem. Thus, this study was done to understand the impacts of chemically synthesized magnetite nanoparticles on earthworm—Eudrilus eugeniae, a soil-dependent organism which acquires food and nutrition from decaying matters. The chemically synthesized magnetite nanoparticles were characterized by UV–visible spectrophotometry, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. Earthworms were allowed to interact with different concentrations of synthesized nanoparticles and the effect of the nanoparticles was analysed by studying the phenotypic changes followed by histology and inductively coupled plasma optical emission spectrometry analyses.
- Synthesis and characterization of nano-hydroxyapatite in maltodextrin
Abstract: Abstract In this study, we report the direct precipitation of nano-HA in the present of maltodextrins with the different dextrose equivalent (DE) values in the range of 10–30. Characterization of the obtained samples, using X-ray diffraction and Fourier transform infrared spectrophotometry, indicated that the presence of maltodextrins, with the different DE values, does not affect the phase composition and structure of the obtained composites. Morphology studies of the samples, using field emission scanning electron microscope and transmission electron microscope, revealed that maltodextrin has obvious effect on the size, shape, and morphology of hydroxyapatite nanoparticles. In particular, in studied DE range, maltodextrin DE 28–30 with dominant structure of debranched chain is the most preferable choice to obtain the composite with highly dispersed nanoparticles. In vitro assay on pre-osteoblast MC3T3-E1 cells demonstrated the ability of the composites to stimulate alkaline phosphatase activity and mineralization during differentiation of the cells.
- Lithium storage study on MoO 3 -grafted TiO 2 nanotube arrays
Abstract: Abstract Titanium dioxide nanotube arrays (TNAs) were fabricated via anodic ionization. Porous MoO3 was grafted on TNAs with the help of hydrothermal method. Scanning electron microscopy and X-ray powder diffraction was utilized for the confirmation of one dimensional morphology and phase identification. The porous MoO3 nanoflake-grafted TNAs (MoO3/TNAs) electrode was used as anode material in lithium ion battery (LIB) and it was found that the areal specific capacity of MoO3/TNAs (~797 µAh cm−2) was three times higher than those of anatase TNAs (~287 µAh cm−2) and porous MoO3 (~234 µAh cm−2) at 50 µA cm−2.
- Controlling the shell microstructure in a low-temperature-grown SiNWs and
Abstract: Abstract We report here the effect of a controlled modification of the shell microstructure around the crystalline core of a silicon nanowire (SiNW) grown at a low (320 °C) temperature by the hot wire chemical vapor processing (HWCVP) method. We demonstrate these effects through the evaluation of the performance of a micro-supercapacitor (µ-SC) device fabricated with these SiNWs having different shell structures. It is to be emphasized that the shell microstructure could be modified through a controlled interplay of the process parameters during the growth. A careful optimization of the shell microstructure in these nanowires during its low-temperature deposition has led to a µ-SC with capacitance value of 94 µF/cm2. This result opens up exciting opportunities for HWCVP-grown SiNWs to be employed for on-chip µ-SC and other low-temperature applications.
- 3D nanoimprint for NIR Fabry-Pérot filter arrays: fabrication,
characterization and comparison of different cavity designs
Abstract: Abstract We report on the fabrication of miniaturized NIR spectrometers based on arrays of multiple Fabry-Pérot (FP) filters. The various cavities of different height are fabricated via a single patterning step using high resolution 3D nanoimprint technology. Today, low-cost patterning of extended cavity heights for NIR filters using the conventional spin-coated nanoimprint methodology is not available because of insufficient coating layers and low mobility of the resist materials to fill extended cavity structures. Our investigation focuses on reducing the technological effort for fabrication of homogeneous extended cavities. We study alternative cavity designs, including a new resist and apply large-area 3D nanoimprint based on hybrid mold and UV Substrate Conformal Imprint Lithography (UV-SCIL) to overcome these limitations. We compare three different solutions, i.e. (1) applying multiple spin coating of the resist to obtain thicker initial resist layers, (2) introducing a hybrid cavity (combination of a thin oxide layer and the organic cavity) to compensate the height differences, and (3) optimizing the imprint process with a novel resist material. The imprint results based on these methods demonstrate the implementation of NIR FP filters with high transmission intensity (best single filter transmission >90 %) and small line widths (<5 nm in full width at half maximum).