Sliver Nanoparticles Research Articles

The preparation of a recyclable catalyst of silver nanoparticles dispersed in a mesoporous silica nanofiber matrix

A recyclable catalyst of sliver nanoparticles well dispersed in mesoporous silica was successfully synthesized via a straight-forward strategy combining an electrospinning technique with post-calcination.

Structural and morphological study of gamma‐irradiation synthesized silver nanoparticles

Silver nanostructured particles with controlled size, shape, and morphology were achieved by gamma irradiation of aqueous solution containing AgNO3, ploy (vinyl pyrrolidone), (PVP) or mixture of PVP and ploy (vinyl alcohol), (PVA). The reaction condition parameters such as solvent content, polymer type and irradiation dose were investigated. The physico‐chemical properties and morphological structures of the as‐prepared sliver nanostructures were characterized using UV/VIS spectroscopy, TEM, XRD, and Fourier transform infrared spectroscopy (FTIR) spectroscopy. Hexagonal and nanorods structures of sliver nanoparticles having single surface plasmon resonance peak and triangular (nanoprism) nanoparticles having different surface plasmon resonance peak were obtained. The XRD patterns of the as‐prepared silver nanostructure show four diffraction peaks at 2θ of 38.4°, 44.5°, 64.6°, and 77.6° of the face‐centered cubic structure silver nanoparticles. FTIR measurements indicated that the sliver nanoparticles were coordinated through the functional groups of PVA and/or PVP. POLYM. COMPOS., 38:2687–2694, 2017. © 2015 Society of Plastics Engineers

4-fold photocurrent enhancement in ultrathin nanoplasmonic perovskite solar cells.

Although perovskite materials have been widely investigated for thin-film photovoltaic devices due to the potential for high efficiency, their high toxicity has pressed the development of a solar cell structure of an ultra-thin absorber layer. But insufficient light absorption could be a result of ultra-thin perovskite films. In this paper, we propose a new nanoplasmonic solar cell that integrates metal nanoparticles at its rear/front surfaces of the perovskite layer. Plasmon-enhanced light scattering and near-field enhancement effects from lumpy sliver nanoparticles result in the photocurrent enhancement for a 50 nm thick absorber, which is higher than that for a 300 nm thick flat perovskite solar cell. We also predict the 4-fold photocurrent enhancement in an ultrathin perovskite solar cell with the absorber thickness of 10 nm. Our results pave a new way for ultrathin high-efficiency solar cells with either a lead-based or a lead-free perovskite absorption layer.

Nanoimprinted Patterned Pillar Substrates for Surface-Enhanced Raman Scattering Applications.

A pragmatic method to deposit silver nanoparticles on polydopamine-coated nanoimprinted pillars for use as surface-enhanced Raman scattering (SERS) substrates was developed. Pillar arrays consisting of poly(methyl methacrylate) (PMMA) that ranged in diameter from 300 to 500 nm were fabricated using nanoimprint lithography. The arrays had periodicities from 0.6 to 4.0 μm. A polydopamine layer was coated on the pillars in order to facilitate the reduction of silver ions to create silver nucleation sites during the electroless deposition of sliver nanoparticles. The size and density of silver nanoparticles were controlled by adjusting the growth time for the optimization of the SERS performance. The size of the surface-adhered nanoparticles ranged between 75 and 175 nm, and the average particle density was ∼30 particles per μm(2). These functionalized arrays had a high sensitivity and excellent signal reproducibility for the SERS-based detection of 4-methoxybenzoic acid. The substrates were also able to allow the SERS-based differentiation of three types of bacteriophages (λ, T3, and T7).

Electrochemical assay of α-glucosidase activity and the inhibitor screening in cell medium.

An electrochemical method is established in this work for the assay of α-glucosidase activity and the inhibitor screening through one-step displacement reaction, which can be directly used in cell medium. The displacement reaction can be achieved via strong binding of 4-aminophenyl-α-D-glucopyranoside (pAPG)/magnetic nanoparticles (MNPs) to pyrene boric acid (PBA) immobilized on the surface of graphite electrode (GE), compared to that of dopamine (DA)/sliver nanoparticles (AgNPs). Since α-glucosidase can specifically catalyze MNPs/pAPG into MNPs/pAP which has no binding capacity with PBA, the activity of both isolated and membrane bound enzyme can be well evaluated by using this proposed method. Meanwhile, signal amplification can be accomplished via the immobilization of DA at the outer layer of AgNPs, and the accuracy can be strengthened through magnetic separation. Moreover, this method can also be utilized for inhibitor screening not only in the medium containing the enzyme but also in cell medium. With good precision and accuracy, it may be extended to other proteases and their inhibitors as well.

Green Synthesis, Characterization and Antimicrobial Potential of Sliver Nanoparticles Using Three Mangrove Plants from Indian Sundarban

Green synthesis of silver nanoparticles (AgNPs) is an alternative to the conventional synthesis procedures which includes physical and chemical methods mostly requiring toxic chemicals, energy, high temperature, and pressure. This study involves biosynthesis of AgNPs using mangroves, a salt-tolerant tidal vegetation with very unique morphology and unusual physiological processes. Our study reports the first ever use of three mangrove plants from Indian Sundarban for bioreduction, namely Avicennia alba, Sonneratia caseolaris, and Sonneratia apetela. The biosynthesized AgNPs were characterized by UV–vis spectroscope, particle size analyzer, scanning electron microscope, transmission electron microscope, energy dispersive X-ray spectrometer, and atomic force microscope. Antimicrobial activities of these AgNPs were assessed against Escherichia coli, Agrobacterium tumefaciens, Streptococcus mutans, Staphylococcus aureus, Tricophyton rubrum, and Aspergillus flavus. Biosynthesized AgNPs showed absorption maxima between 419 and 448 nm which corresponds to their respective surface plasmon resonance. Previous biosynthesis of AgNPs using mangrove plants have reported 60–110 nm average particle size, whereas in our study, S. caseolaris was the most potent bioreductant which synthesized AgNPs with average diameter (D90%) of 18.3 nm. The particles exhibited considerable antimicrobial activities against all six microorganisms. AgNPs synthesized by S. caseolaris using 5 ppm AgNO3 showed the most significant activity with maximum zone of inhibition (13.5 ± 0.8 mm) against E. coli.

Characterization and Preparation of Sago Starch (SS) Based Reinforced with Silver Nanoparticle (SNP)

This paper reported on the properties of sago starch (SS) films impregnated with different concentration of sliver nanoparticles (SNP) of 100, 2000, 5000 rpm with weight ratio of 1% and 10% to be used as wound healing material. The SS films were prepared through film moulding technique by mixing aqueous SNP with SS, glycerol and water at weight percentage of 6.5:3.5:90. The performance of SS-SNP films produced is studied. The morphology study shows the existence of SNP embedded in the SS particles. SNP with 2000ppm has the biggest particle width but small in particle sizes, which make the SS-SNP film of 2000ppm is superior in thickness, denser and has lower moisture content compared to other SS-SNP film with different composition. The highest water absorption occurred in the SS-SNP of 100ppm, due to the high existence of pores in the network of amylose content in starch. SNP act as particulate reinforcement in the SS film meaning higher number of ppm made the film more brittle and easy to rupture. Thus, the SS-SNP film of 5000ppm has the lowest tensile strength and modulus for tensile strength and modulus. It can be concluded that the SS-SNP film of 2000ppm is suitable to be used as wound healing material, as the addition of 2000ppm SNP inside the SS films help in improving the properties of SS-SNP film produced.

Photocatalytic activity of carbon nanofibers loading AgBr–TiO2 composites under visible light irradiation

Carbon nanofibers (CNFs) containing sliver nanoparticles (Ag NPs) were prepared via in situ reduction, electrospinning, and high-temperature calcination technique. Tetrabutyl titanate, the precursor of titanium dioxide (TiO2), was adsorbed to the surface of Ag/CNFs by physical adsorption process. Ag–TiO2/CNFs nanocomposites were obtained by high-temperature calcination treatment. Then, Ag NPs were oxidized to sliver bromide (AgBr) using bromine (Br2) as an oxidant. The characterizations of scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, proved that AgBr and anatase TiO2 NPs deposited on the surface of CNFs. The photocatalytic experiments exhibited that the as-prepared AgBr–TiO2/CNFs were easily recycled and the introduction of AgBr NPs made them possess well photocatalytic activity under visible light (λ ≥ 400 nm).

Synthesis and characterization of Ag nanoparticles decorated mesoporous sintered activated carbon with antibacterial and adsorptive properties

In this study, the sliver nanoparticles (AgNPs) immobilized on the sintered activated carbon (Ag/SAC) were synthesized by the ultrasonic-assisted impregnation method and were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and nitrogen adsorption. SEM showed that the AgNPs were well embedded in the SAC and immersion time had an important influence on final morphologies of AgNPs. Longer immersing duration caused significant aggregation of the AgNPs. The XRD data revealed that the successful synthesis of AgNPs on the SAC and immobilizing AgNPs on sintered active carbon did not change the crystalline degree of SAC. Texture characteristics were determined by analysis of the N2/77 K isotherms. The minimum inhibitory concentration (MIC) of Ag/SAC against Escherichia coli (DH5α) and Staphyloccocus aureus (ATCC 29213) was evaluated by a broth dilution method. MICs such as 5 mg/L (against E. coli) and 10 mg/L (against S. aureus) suggest that Ag/SAC have predominant antibacterial activity compared to active carbon.

Isolation and Molecular Characterization of Heavy Metal-Resistant Alcaligenes faecalis from Sewage Wastewater and Synthesis of Silver Nanoparticles

Environmental pollution with toxic heavy metals is increasing throughout the world alongside industrial development. Microorganisms and microbial products can be highly efficient bioaccumulators of soluble and particulate forms of metals, especially dilute external solutions. Microbe related technologies (Biotechnology) may provide an alternative or additive conventional method for metal removal or metal recovery. This study dealt with isolation, identification and characterization of heavy metal-resistant (Pb2+, Cd2+, Al3+, Cu2+, Ag2+ and Sn2+) bacteria from sewage wastewater at Taif Province, Saudi Arabia. Nine bacterial isolates were selected by using an enrichment isolation procedure based on high level of heavy metal resistance. All the isolates showed high resistance to heavy metals with Minimum Inhibitor Concentration (MIC) ranging from 800 μg/ml to 1400 μg/ml. All nine resistant isolates showed multiple tolerances to heavy metals. On the basis of morphological, biochemical and 16S rRNA characterization, the most potent isolates (Cd1-1, Ag1-1, Ag1-3 and Sn1-1) were identified as Alcaligenes faecalis. Scanning electron microscope analysis showed that the morphology of Alcaligenes faecalis Ag1-1 was unchanged after growth in medium without and with addition of Ag2+ indicative Ag2+ is not toxic to the isolate under the conditions tested. The ability of Alcaligenes faecalis Ag1-1 to synthesize sliver nanoparticles was examined. The heavy metal-resistant bacteria obtained could be useful for the bioremediation of heavy metal-contaminated environment.

不同密度银纳米粒子对氧化锌基发光二极管发光的增强

不同密度银纳米粒子对氧化锌基发光二极管发光的增强

Current approaches of managing microbial diseases: focus on nanosciences technique

Nanoscience is a fast growing research area that focuses on producing and utilizing nano- sized particles, which are measured in nanometers. Recently, nanoparticles are used in various fields. Therefore, studies on the effect of nanoparticles on microorganisms are worthy of analysis. However, using many antimicrobial agents has been avoided because of their methodical harmful effect. Hence, this review paper focuses on the use of some nanomaterials to manage microbial diseases. The discussed nanomaterials as antimicrobial agents include sliver nanoparticles, gold nanoparticles and copper nanoparticles. This review also explains the mechanisms of action of some nanotechnological products to inhibit microorganisms. There are many problems in the development of an evaluation for the effect of nanomaterials on environment. Nevertheless, the defect of the approaches used to analyze nanomaterials toxicity gives no ground for hampering the development of nanotechnologies for safety using. In order to overcome this problem, ecotoxicological studies should be extended to include the analysis of the biological safety of nanomaterials in environment and accumulate experimental data.

A hydrogen peroxide electrochemical sensor based on silver nanoparticles decorated three-dimensional graphene

A facile strategy has been developed to synthesize sliver nanoparticles (Ag NPs) decorated three-dimensional graphene (3DG) through hydrothermal process. The AgNPs-3DG composites are directly fabricated into a free standing sensing electrode for electrochemical detection of hydrogen peroxide (H2O2) in phosphate buffered solutions. Various techniques equipments including scanning electron microscopy, X-ray diffraction, and Raman spectroscopy are used to characterize the morphology and structure of the as-prepared composite. The electrochemical experiments reveal the AgNPs-3DG based biosensor exhibits fast amperometric sensing, low detection limitation, wide linear responding range, and perfect selectivity for non-enzyme H2O2 detection, indicating the well synergistic effect of Ag NPs high electrocatalytic activity and 3DG high conductivity and large surface area.

Antidiabetic Activity of Zinc Oxide and Silver Nanoparticles on Streptozotocin-Induced Diabetic Rats

The use of nanoparticles in medicine is an attractive proposition. In the present study, zinc oxide and silver nanoparticles were evaluated for their antidiabetic activity. Fifty male albino rats with weight 120 ± 20 and age 6 months were used. Animals were grouped as follows: control; did not receive any type of treatment, diabetic; received a single intraperitoneal dose of streptozotocin (100 mg/kg), diabetic + zinc oxide nanoparticles (ZnONPs), received single daily oral dose of 10 mg/kg ZnONPs in suspension, diabetic + silver nanoparticles (SNPs); received a single daily oral dose of SNP of 10 mg/kg in suspension and diabetic + insulin; received a single subcutaneous dose of 0.6 units/50 g body weight. Zinc oxide and silver nanoparticles induce a significant reduced blood glucose, higher serum insulin, higher glucokinase activity higher expression level of insulin, insulin receptor, GLUT-2 and glucokinase genes in diabetic rats treated with zinc oxide, silver nanoparticles and insulin. In conclusion, zinc oxide and sliver nanoparticles act as potent antidiabetic agents.

Air Heating Approach for Multilayer Etching and Roll-to-Roll Transfer of Silicon Nanowire Arrays as SERS Substrates for High Sensitivity Molecule Detection

SiNW array represents an attractive system for construction of high-performance energy, electronic, and sensor devices. To meet the demand for flexible devices as well as address the concern about the full use of the Si material, large-area transfer of the SiNW array from growth substrate is very desirable. Here, we report a simple air heating approach to achieve the multilayer etched SiNW array. This method allows the fabrication of up to a five-layer (while perfectly three-layer) cracked SiNW array on single-crystalline Si wafer via a templateless metal-assisted etching approach. Fractures could happen at the crack position when an appropriate pressure was applied on the SiNW array, facilitating the wafer-scale layer-by-layer transfer of the SiNW array onto a flexible substrate through a low-cost and time-efficient roll-to-roll (R2R) technique. Further releasing of the SiNW array to other receiving substrates was accomplished with the aid of a thermal release tape. After modification with sliver nanoparticles (AgNPs), the flexible SiNW array showed great potential as a high-sensitivity surface-enhanced Raman spectroscopy (SERS) substrate for detecting rhodamine 6G (R6G) molecule with concentration as low as 10(-9) M.

Influence of silver nanoparticles on Er3+ up-conversion in CaF2 precipitated oxyfluoride glass-ceramics

The influence of silver nanoparticles on Er3+ up-conversion in CaF2 precipitated oxyfluoride glass-ceramics is investigated. After heat-treatments, transmission electron microscopy images show that CaF2 nanocrystals precipitate in the glass matrix uniformity, and sliver nanoparticles are spread around the CaF2 nano-crystals simultaneously. Comparing with the samples without Ag doped, high efficiency up-conversion luminescences of Er3+ at 540 and 658 nm are distinctly observed in the silver nanoparticles containing glass-ceramics by the 980-nm excitation. Moreover, since the intensity ratio of green and red emissions changes after silver nanoparticles precipitation, the up-conversion mechanism of Er3+ is discussed.

Sliver nanoparticles accelerate skin wound healing in mice (Mus musculus) through suppression of innate immune system

Objective(s): This study aimed to find the effects of silver nanoparticles (Ag-NPs) (40 nm) on skin wound healing in mice Mus musculus when innate immune system has been suppressed.Materials and Methods: A group of 50 BALB/c mice of about 8 weeks (weighting 24.2±3.0 g) were randomly divided into two groups: Ag-NPs and control group, each with 25 mice. Once a day at the same time, a volume of 50 microliters from the nanosilver solution (10ppm) was applied to the wound bed in the Ag-NPs group while in the untreated (control) group no nanosilver solution was used but the wound area was washed by a physiological solution. The experiment lasted for 14. Transforming growth factor beta (TGF-β), complement component C3, and two other immune system factors involving in inflammation, namely C-reactive protein (CRP) and rheumatoid factor (RF) in sera of both groups were assessed and then confirmed by complement CH50 level of the blood. Results: The results show that wound healing is a complex process involving coordinated interactions between diverse immunological and biological systems and that Ag-NPs significantly accelerated wound healing and reduce scar appearance through suppression of immune system as indicated by decreasing levels of all inflammatory factors measured in this study. Conclusion: Exposure of mice to Ag-NPs can result in significant changes in innate immune function at the molecular levels. The study improves our understanding of nanoparticle interaction with components of the immune system and suggests that Ag-NPs have strong anti-inflammatory effects on skin wound healing and reduce scarring.

The synergetic antibacterial activity of Ag islands on ZnO (Ag/ZnO) heterostructure nanoparticles and its mode of action

Sliver nanoparticles (NPs) possess wonderful antibacterial activity while ZnO is a promising photocatalyst. Although it has been reported that the photocatalytic activity of Ag/ZnO heterostructure nanoparticles (HNPs) was better than that of pure ZnO NPs, the existing comparisons on their antibacterial activity were all taken between Ag-doped ZnO HNPs and pure Ag NPs (or pure ZnO NPs), and were still controversial. Ag islands on ZnO, another type of Ag/ZnO HNPs, were synthesized by a two-step preparation and characterized in this work. The antibacterial activity of as-synthesized Ag/ZnO HNPs, especially with 5.0wt.% of Ag, against Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923) was enhanced greatly in contrast with that of the simple mixture of Ag and ZnO NPs. The enhancement was found to be mainly due to the obvious increase in the reactive oxidative species (especially superoxide) and the increased damage to plasmid DNA induced by Ag/ZnO HNPs.

English

Biological silver nanoparticles were successfully synthesized from a simple green and natural route using the extract of Allium cepa (onion) with the use of silver nitrate as precursor and chemically synthesized using silver nitrate and tri sodium citrate. Nanoparticle synthesis was proven under UV-Visible absorption spectroscopy. Toxicity of sliver nanoparticles was tested using ToxTrak test, in which, fresh overnight broths of Bacillus subtilis and resazurin dye were used to calculate percentage inhibition (PI). PI is only a relative measure and since there is toxic substances that increase respiration, to give result to a negative number. The PI of both chemically and biologically synthesized silver nanoparticles was compared in order to evaluate toxic effect value. The toxic effect value, PI of chemically synthesized silver nanoparticles is much greater (85.45%) than the biologically synthesized sliver nanoparticles from onion (51.39%). These observation shows that the bacteria B. subtilis killed by chemically synthesized silver nanoparticles are more as compare to biologically synthesized sliver nanoparticle.   Key words: Silver nanoparticles, Allium cepa, ToxTrak toxicity test, resazurin dye, ultraviolet spectroscopy, Bacillus subtilis and percentage inhibition (PI).

Morphological and antibacterial properties of modified paper by PS nanocomposites for packaging applications

With the increasing sustainability trend with packaging materials, paper and polymer nanocomposites represent a novel class of packaging materials. This study evaluates the potential achievement of alternative sustainable materials as antibacterial packaging application. Paper sheet from rice straw coated with 5 or 10% polystyrene (PS) nanocomposites using titanium dioxide nanoparticles (TiO2-NPs) doped or undoped with sliver nanoparticles (Ag-NPs) were prepared. The morphology of the uncoated and coated paper sheets was studied by SEM. The treated paper sheets were analyzed for their elemental composition using EDAX. The Barrier, air permeability, cob test, as well as mechanical properties and tensile strength were also evaluated. The inhibitory effect of modified paper sheets against Pseudomonas, Staphylococcus aureus, Candida, and Staphylococcus were investigated.