Silver Nanoparticle Suspensions Research Articles

In vitro Antifungal Efficacy of Silver Nanoparticles against Fusarium oxysporum f. sp. Lycopersici in Tomato

Present investigation on Mycosynthesis of silver nanoparticles and antifungal activity of silver nanoparticles against Fusarium oxysporum f. sp. lycopersici in tomato was carried out at department of Plant Pathology, College of Agriculture, Latur to find out antifungal activity of silver nanoparticles against Fusarium oxysporum f. sp. lycopersici in tomato. Mycosynthesis of silver nanoparticles produced from the fungus Trichoderma harzianum. Characterization of silver nanoparticles were carried out by UV-Vis spectroscopy and Transmission Electron Microscopy (TEM) which revealed that synthesized nanoparticles were having the UV absorption peak at 420 nm and nanoprticle size was 50 nm. Silver nanoparticles demonstrated significant antifungal activity against Fusarium oxysporum f. sp. lycopersici in tomato by using Agar well diffusion method and Poisoned food technique. In Agar well diffusion method, the highest zone of inhibition 18.66 mm was recorded at 100 ppm concentration than other treatments. In poisoned food technique, the suspension of silver nanoparticles at 100 ppm concentration recorded highest (75.19%) inhibition. This was followed by 50 ppm, 30 ppm, 10 ppm conc. and Trichoderma culture filtrate which recorded 66.67%, 58.89%, 54.45% and 51.45% inhibition, respectively. Growth of the Fusarium oxysporum f. sp. lycopersici in tomato decreased drastically with increase in the concentration of the silver nanoparticles.

Colloidal Self-Assembly of Silver Nanoparticle Clusters for Optical Metasurfaces.

Optical metasurfaces are two-dimensional assemblies of nanoscale optical resonators and could constitute the next generation of ultrathin optical components. The development of methods to manufacture these nanostructures on a large scale is still a challenge, while most performance demonstrations were obtained with lithographically fabricated metasurfaces that are restricted to small scales. Self-assembly fabrication routes are promising alternatives and have been used to produce original nanoresonators. Reports of self-assembled metasurface fabrication, however, are still scarce. Here, we show that an emulsion-based formulation approach can be used both for the fabrication of complex colloidal resonators, presenting a strong interaction with light, in particular due to simultaneous magnetic and electric modes of resonance, and for their deposition in homogeneous films. This fabrication technique involves emulsification of an aqueous suspension of silver nanoparticles in an oil phase, followed by controlled drying of the emulsion, and produces silver colloidal clusters. We show that the drying process can be controlled in a liquid emulsion, producing a metafluid, as well as in a sedimented emulsion, producing a metasurface. The structural control of the synthesized colloidal clusters is demonstrated with electron microscopy and X-ray scattering techniques. Using a polarization-resolved multiangle light scattering setup in the visible wavelength range, we conduct a comprehensive angular and spectroscopic study of the optical resonant scattering of the nanoresonators in a metafluid and show that they present strong optical magnetic resonances and directional forward-scattering patterns, with scattering efficiencies of up to 4. The metasurfaces consist of homogeneous films, of variable surface density, of colloidal clusters that have the same extinction properties on the surface and in the fluid. This experimental approach allows for large-scale production of metasurfaces.

Generation of entropy on blood conveying silver nanoparticles embedded in curved surfaces

The brain is a complicated system that experiences energy and energy exchange problems. While silver nanoparticles are essential in cancer treatment, entropy analysis can be used to study the brain and its illness. In addition to the nature of the blood's thermophysical properties and the utility of silver nanoparticles over curved stretched surfaces, nothing is known about the dynamics of transient blood carrying silver nanoparticles when entropy generation and Lorentz force are important. So, a transitory irreversibility analysis problem (entropy generation/s law analysis) is studied in this work. As a counter example to Casson fluid, blood is used as the base fluid, which has a suspension of silver nanoparticles on a curved, stretched surface. Convective boundary conditions and thermal radiation are considered. By using the necessary similarity transformations, the governing equations for the current flow are converted into a nonlinear system. The finite element method is employed to obtain multiple results for the condensed system. The significance of various emerging parameters related to current study is stimulated and analyzed thoroughly trough the graphs of profiles of temperature and velocity, moreover, temperature gradient and drag force are also taken into account. The outcomes indicating that radiation and dissipation effects increase entropy As a result, entropy can play a crucial role in the artificial process used to analyze brain activity. Due to the presence of silver nanoparticles in blood flow, the velocity and temperature also increase.

The protective effect of silver nanoparticles' on epithelial cornea cells against ultraviolet is accompanied by changes in calcium homeostasis and a decrease of the P2X7 and P2Y2 receptors

PurposeThe aim of the study was to evaluate the effect of silver nanoparticles hydrocolloids (AgNPs) on human corneal epithelial cells. Epithelial cells form the outermost and the most vulnerable to environmental stimuli layer of the cornea in the eye. Mechanical stress, UV radiation, and pathogens such as bacteria, viruses, and parasites challenge the fragile homeostasis of the eye. To help combat stress, infection, and inflammation wide portfolio of interventions is available. One of the oldest treatments is colloidal silver. Silver nanoparticle suspension in water is known for its anti-bacterial anti-viral and antiprotozoal action. However, AgNPs interact also with host cells, and the character of the interplay between corneal cells and silver seeks investigation. MethodsThe human epithelial corneal cell line (HCE-2) was cultured in vitro, treated with AgNPs, and subjected to UV. The cell’s viability, migration, calcium concentration, and expression/protein level of selected proteins were investigated by appropriate methods including cytotoxicity tests, “wound healing” assay, Fluo8/Fura2 AM staining, qRT-PCR, and western blot. ResultsIncubation of human corneal cells (HCE-2) with AgNP did not affect cells viability but limited cells migration and resulted in altered calcium homeostasis, decreased the presence of ATP-activated P2X7, P2Y2 receptors, and enhanced the expression of PACAP. Furthermore, AgNPs pretreatment helped restrain some of the deleterious effects of UV irradiation. Interestingly, AgNPs had no impact on the protein level of ACE2, which is important in light of potential SARS-CoV-2 entrance through the cornea. ConclusionsSilver nanoparticles are safe for corneal epithelial cells in vitro.

Theoretical study of silver nanoparticle suspension in electroosmosis flow through a nonuniform divergent channel with compliant walls: A therapeutic application

This study explores the effect of silver nanoparticles on heat transfer and flow behavior within the context of the Ellis fluid model. It specifically considers electroosmotic forces in a nonuniform divergent channel with compliant walls. The analysis involves studying thermal transport in silver-blood nanofluid flow, using MATHEMATICA 13.2 software to obtain exact solutions for velocity and temperature distribution. Findings reveal that certain parameters, such as wall damping and wall elastic properties, increase skin friction, while compliant wall parameters generally reduce flow velocity. Additionally, wall rigidity and tension parameters lead to larger trapped boluses. Notably, a 1% concentration of nanoparticles enhances heat transfer by up to 13.75%, offering control over heat transfer rates. This research introduces a novel perspective by examining compliant wall impacts on heat transfer analysis in the context of electroosmotic flow within the Ellis fluid model, incorporating silver nanoparticles with potential therapeutic applications due to their antibacterial properties.

Irreversibility treatment and colloidal suspension of gold and silver nanoparticles in a microchannel

The silver and gold nanoparticles show noteworthy outcomes on anticancer therapies and antimicrobials. The silver was the noticeable anti-swelling and gold nanoparticles efficiently helped to convert these photons by heat into demolished cancer cells. So, the purpose of this work is devoted to studying the effect of linear radiation on the hybrid nanoparticles (gold and silver with hemoglobin) in a microchannel. This dimensionless numerical expression was determined mathematically into the finite element method. The second law study was required to predict these sources by irreversibility approximate into that thermal system. Although the comprehensive parametric analysis was well-known in the production of entropy may be enhanced into viscous dissipation and radiation form. That was established in the hybrid nanoparticles shows the greater Bejan number related to both hemoglobin and nanofluid.

Comparison of the resistivities of nanostructured films made from silver, copper-silver and copper nanoparticle and nanowire suspensions

Spray deposition and inkjet printing of various nanostructures are emerging complementary methods for creating conductive coatings on different substrates. In comparison to established deposition techniques like vacuum metal coating and lithography-based metallization processes, spray deposition and inkjet printing benefit from significantly simplified equipment. However, there are number of challenges related to peculiar properties and behaviour of nanostructures that require additional studies. In present work, we investigate electroconductive properties and sintering behaviour of thin films produced from nanostructures of different metals (Ag, Cu and Cu-Ag) and different shapes (nanowires and spherical nanoparticles), and compare them to the reference Ag and Cu magnetron deposited films. Synthesized nanostructures were studied with transmission electron microscopy. Morphology and crystallinity of produced metal films were studied with scanning electron microscopy and X-ray diffraction. The electrical parameters were measured by the van der Pauw method. All nanowires-based films provided high conductivity and required only modest thermal treatment (200 °C). To achieve sufficient sintering and conductivity of nanoparticles-based films, higher temperatures are required (300 °C for Ag nanoparticles and 350 °C for Cu and Cu-Ag nanoparticles). Additionally, stability of nanowires was studied by annealing the samples in vacuum conditions inside a scanning electron microscope at 500 °C.

Antimicrobial Activity of Silver Nanoparticles on Pathogenic Bacteria

Nosocomial infection is acquired contamination of hospitals and health care units caused by multidrug resistant bacteria. Currently, bacterial resistance to antimicrobial medication represents a complicated public health problem. Recent studies on the antimicrobial activity of silver nanoparticles (AgNPs) attracted researchers worldwide to focus on the safe synthesis of AgNPs as antimicrobial agents against multidrug resistant bacteria. The antimicrobial efficacy of AgNPs on pathogenic bacteria isolated from clinical cases of acquired hospital infection was targeted in this project. Fifty specimens of stool were collected through private laboratories in Baghdad from patients who suffered diarrheal symptoms. Bacterial isolation, identification, and characterization via culturing on MacConkey agar, Salmonella shigella agar, and IMVic analysis were done besides, using polymerase chain reaction (PCR) through amplifying inf B gene for molecular characterization. The obtained isolates were tested for antimicrobial sensitivity via disk diffusion assay against; Gentamycin, Amoxicillin, Tetracycline, Ceftriaxone and a suspension of silver nanoparticles (1mM AgNo3 reduced by 1% tri-sodium citrate). Results of isolation and IMVic showed the obtained isolates were Klebsiella spp., Enterobacter spp., Citrobacter spp., and PCR assay confirmed their pathogenicity. Disc diffusion assay showed the sensitivity of the isolates (mm); Gentamycin (24.94 ± 0.1), Amoxicillin (2.11 ± 0.13), Tetracycline (12.15 ± 0.1), Ceftriaxone (12.35 ± 0.1). Whereas, all isolates are sensitive to AgNPs (24.12 ± 0.3). This result of the antimicrobial effect of AgNPs on nosocomial infection promises for developing AgNPs solution as a product used in the sterilization of furniture, floors and hospital water cycles

CFD and thermal analysis of radiator using magnesium oxide and silver nano fluids

The utilisation of magnesium oxide and silver nanofluids in radiators presents various advantages. In addition to improving heat transfer, these fluids have the ability to reduce the energy consumption required for cooling. This phenomenon can be attributed to the significantly higher thermal conductivity exhibited by them in comparison to water. Moreover, these fluids exhibit exceptional tolerance to elevated temperatures without undergoing corrosion or degradation, rendering them highly suitable for challenging environmental circumstances in radiator implementations. A computational fluid dynamics (CFD) analysis was performed using Ansys Fluent software to evaluate the effectiveness of magnesium oxide and silver nanofluids in radiators. Subsequently, a comparison was made between the results obtained from the aforementioned approach and those derived from a traditional aqueous system. The findings unambiguously demonstrated a noteworthy improvement in thermal conductivity upon employing magnesium oxide and silver nanoparticles suspensions, relative to the aqueous medium. Moreover, the application of these fluids resulted in a decrease of up to 20% in the total cooling power demand. The results of this study highlight the significant benefits provided by the utilisation of magnesium oxide and silver nano fluids in comparison to conventional water-based systems. Hence, it is imperative to give due consideration to their viability as a potential alternative while devising novel radiator systems or enhancing the existing ones.

Quadratic convection on the radiative flow of ternary nanofluid Gr–Ag–TiO2–H2O subjected to velocity slip and temperature jump

This paper deals with the analysis of the flow and heat transfer performance of ternary nanofluid flowing past a stretching sheet under the influence of quadratic convection. The ternary nanofluid is formed by suspending three different nanoparticles, namely, titanium dioxide (TiO2), silver (Ag) and graphene (Gr) in the base fluid water (H2O). Thus, the ternary nanofluid obtained is Gr–Ag–TiO2/H2O where the hybrid nanofluid Ag–TiO2/H2O forms the base fluid for the resulting ternary nanofluid. The addition of TiO2 nanoparticles enhances the photocatalytic nature of the base fluid and makes it useful in various applications concerning the medicinal field. The presence of Gr helps in intensifying the thermal conductivity of water while the suspension of silver nanoparticles ensures chemical stability. Meanwhile, the thermophysical properties of the ternary nanofluid are mathematically defined and the system of equations that describe the flow of a ternary nanofluid past a stretching sheet is framed using differential equations. The outcomes of this study are interpreted through graphs for velocity and temperature profiles of the ternary nanofluid. It was mainly observed that the thermal conductance of ternary nanofluid was higher than the monophase and hybrid nanofluid. Also, the presence of quadratic convection had a prominent impact on the ternary nanofluid flow. The Nusselt number was found to be greater for spherical nanoparticles and it was found to be least for blade-shaped nanoparticles.

Biosynthesis and numerical investigation of radiative heat transfer in silver-blood nanofluid flow through cosine-shaped stenosed artery: a biomedical application

Silver is a well-acknowledged antimicrobial and has wider usage to kill bacteria, as a topical treatment for burns, and as anticancer therapy. Because of this, the current work combines experimental and theoretical examinations on the impact of the external magnetic field, nanoparticle shape factor, and radiative heat in human blood flow. Here the blood is embedded with silver nanoparticles and passes through the cosine-shaped stenosis artery with unobstructed size. The biosynthesis of silver nanoparticles is prepared with moringa oleifera leaves. A mathematical exemplary was developed to scrutinize the control of physical quantities on movement and heat relocation in silver-blood nano liquid. The transformed central equalities are solved mathematically, and outcomes are explored in graphical and tabular illustrations. The obtained results validated the limiting case and found a good agreement. It is remarkable to mention that the silver-blood-lamina mixture heat relocation rate is more advanced than the silver-blood-platelet mixture. Therefore, the suspension of lamina-shaped silver nanoparticles in the blood may help to kill bacteria effectively.

Analysis of the Thomson and Troian velocity slip for the flow of ternary nanofluid past a stretching sheet

In this article, the flow of ternary nanofluid is analysed past a stretching sheet subjected to Thomson and Troian slip condition along with the temperature jump. The ternary nanofluid is formed by suspending three different types of nanoparticles namely text{TiO}_{2}, text{Cu} and text{Ag} into water which acts as a base fluid and leads to the motion of nanoparticles. The high thermal conductivity and chemical stability of silver was the main cause for its suspension as the third nanoparticle into the hybrid nanofluid text{Cu-TiO}_{2}/text{H}_{2} text{O}. Thus, forming the ternary nanofluid text{Ag-Cu-TiO}_{2}/text{H}_{2} text{O}. The sheet is assumed to be vertically stretching where the gravitational force will have its impact in the form of free convection. Furthermore, the presence of radiation and heat source/sink is assumed so that the energy equation thus formed will be similar to most of the real life applications. The assumption mentioned here leads to the mathematical model framed using partial differential equations (PDE) which are further transformed to ordinary differential equations (ODE) using suitable similarity transformations. Thus, obtained system of equations is solved by incorporating the RKF-45 numerical technique. The results indicated that the increase in the suspension of silver nanoparticles enhanced the temperature and due to density, the velocity of the flow is reduced. The slip in the velocity decreased the flow speed while the temperature of the nanofluid was observed to be increasing.

Optimization of Green Synthesized Black Tea Nanoparticles using Central Composite Design

Objectives: Traditional method of optimization is lengthy and time consuming while response surface methodology evaluates the effects of multiple factors and their interactions on one or more response variables with fewer experiments. The aim of present study is optimization of green synthesized black tea nanoparticles using central composite design. Materials and Methods: 5, 15, and 25% black tea concentrations were reacted with 5, 10, and 15 mM Silver nitrate (AgNO3). An optimization study was carried out to optimize the levels of the independent factors like concentration of extract, solution of Silver nitrate, stirring speed, and stirring time. 30 numbers of experiments were performed and evaluated for responses like particle size and % yield. Characterization of silver nanoparticle was done by UV-visible spectroscopy, zeta sizer, XRD, FTIR, FESEM, etc. Results: Nanoparticles formation was revealed by color transformation from light yellow to brown. Prepared particles were monodisperse with Z-Average: 137.8 nm, polydispersity index 0.278, and Zeta potentials 22.7 mV. Electrophoretic Mobility Mean was 0.000176 cm 22/Vs, indicating the stability of silver nanoparticle suspension. Conclusion: Optimized parameters offered by Central Composite Design were 10mM AgNO3, 10% extract of black 150 min, and 700 rpm. 3D plots revealed that the metal salt concentrations and stirring rate showed a direct relationship whereas extract concentration and stirring time showed indirect relationship with particle size. % yield was highest with mid level of solution of metal salt (A) and concentration of extract (B) Stirring time (C) and stirring speed had no impact on % yield.

Physical Interpretation of Nanofluid (Copper Oxide and Silver) with Slip and Mixed Convection Effects: Applications of Fractional Derivatives

A fractional model was developed for presenting the thermal assessment of nanoparticles in an inclined moving surface. Water was used as a base fluid, while the nanofluid utilized copper oxide and silver nanoparticles. The modification of the thermal model was further supported by mixed convection, magnetic force, and porous saturated space. Slip effects to the porous surface were also introduced. The fluctuation in temperature at different times was assumed by following the ramped thermal constraints. The fractional computations for the set of flow problems were performed with implementations of the Atangana–Baleanu (AB) and Caputo–Fabrizio (CF) analytical techniques. The integration process for such computations was achieved using the Laplace transformation. The comparative velocity and thermal analysis for the water and kerosene-oil-based nanofluid model is presented. The declining change in the velocity was observed due to the increase in the volume fraction of nanoparticles. It was observed that the increment in the temperature profile was more progressive for the kerosene oil and silver nanoparticle suspension.

Chitosan/carboxymethyl cellulose wound dressings supplemented with biologically synthesized silver nanoparticles from the ligninolytic fungus Anamorphous Bjerkandera sp. R1

Chitosan (CHI) and carboxymethyl cellulose (CMC) are naturally sourced materials with excellent physical, chemical, and biological properties, which make them a promising tool for the development of different medical devices. In this research, CHI-CMC wound dressings were manufactured, by using different colloidal suspensions of silver nanoparticles (AgNPs) synthesized from the ligninolytic fungus Anamorphous Bjerkandera sp. R1, called CS and SN. Transmission electron microscopy (TEM), UV-Vis spectroscopy, and dynamic light scattering (DLS) analysis were used to characterize AgNPs. The wound dressings were characterized, by scanning electron microscopy (SEM), optical microscopy and their mechanical, antimicrobial, and biological properties were evaluated. The results of the different characterizations revealed the formation of spherical AgNPs with a mean size between 10 and 70 nm for the different mixtures worked. The mechanical properties of CHI-CMS-AgNPs doped with CS and SN suspensions showed superior mechanical properties with respect to CHI-CMC wound dressings. Compared to the latter, CHI-CMC-AgNPs wound dressings yielded better antibacterial activity against the pathogen Escherichia coli. In biological assays, it was observed that manufactured CHI-CMC-AgNPs wound dressings were not toxic when in contact with human skin fibroblasts (Detroit). This study, then, suggests that this type of wound dressings with a chitosan matrix and carboxymethyl cellulose doped with biologically synthesized nanoparticles from the fungus Bjerkandera sp., may be an ideal alternative for the manufacture of new wound dressings.

Cellular Effects of Silver Nanoparticle Suspensions on Lung Epithelial Cells and Macrophages

Background: Silver nanoparticles (AgNPs) are used in industrial applications as catalysts, sanitary materials, and health supplements. Generally, AgNPs have shown cytotoxicity such as cell membrane damage. However, the mechanisms of their toxicity have not been completely elucidated. Methods: The cellular effects (cell viability, induction of chemokine and cellular oxidative stress) of two AgNP water suspensions (AgNP-A for cosmetic application and AgNP-B for industrial application) on epithelial-like A549 cells and macrophage-like differentiated THP-1 (dTHP-1) cells were examined. Results: AgNPs caused enhancement of IL-8 expression and oxidative stress. The cellular uptake of AgNP-A cells was observed. However, the cellular uptake of AgNP-B into A549 cells was hardly observed. Moreover, the intracellular Ag level was increased by AgNP suspensions exposure. Cell viability was not affected by AgNP suspensions exposure. Conclusions: AgNPs induce chemokine expression and cellular oxidative stress on culture cells. The intracellular Ag level may be important for these cellular effects.

Toward In-Field Determination of Nitrate Concentrations Via Diffusive Gradients in Thin Films-Incorporation of Reductants and Color Reagents.

Diffusive gradients in thin films (DGTs) have been established as useful tools for the determination of nitrate, phosphate, trace metals, and organic concentrations. General use of DGTs, however, is limited by the subsequent requirement for laboratory analysis. To increase the uptake of DGT as a tool for routine monitoring by nonspecialists, not researchers alone, methods for in-field analysis are required. Incorporation of color reagents into the binding layer, or as the binding layer, could enable the easy and accurate determination of analyte concentrations in-field. Here, we sought to develop a chitosan-stabilized silver nanoparticle (AuNP) suspension liquid-binding layer which developed color on exposure to nitrite, combined with an Fe(0)-impregnated poly-2-acrylamido-2-methyl-1-propanesulfonic acid/acrylamide copolymer hydrogel [Fe(0)-p(AMPS/AMA)] for the reduction of nitrate. The AuNP-chitosan suspension was housed in a 3D designed and printed DGT base, with a volume of 2 mL, for use with the standard DGT solution probe caps. A dialysis membrane with a molecular weight cutoff of <15 kDa was used, as part of the material diffusion layer, to ensure that the AuNP-chitosan did not diffuse through to the bulk solution. This synthesized AuNP-chitosan provided quantitative nitrite concentrations (0 to 1000 mg L–1) and masses (145 μg) in laboratory-based color development studies. An Fe(III)-impregnated poly-2-acrylamido-2-methyl-1-propanesulfonic acid/acrylamide copolymer hydrogel [Fe(III)-p(AMPS/AMA)] was developed (10% AMPS, and 90% AMA), which was treated with NaBH4 to form an Fe(0)-p(AMPS/AMA) hydrogel. The Fe(0)-p(AMPS/AMA) hydrogel quantitatively reduced nitrate to nitrite. The total nitrite mass produced was ∼110 μg, from nitrate. The diffusional characteristics of nitrite and nitrate through the Fe(III)-p(AMPS/AMA) and dialysis membrane were 1.40 × 10–5 and 1.40 × 10–5 and 5.05 × 10–6 and 5.15 × 10–6 cm2 s–1 at 25 °C respectively. The Fe(0)-hydrogel and AuNP-chitosan suspension operated successfully in laboratory tests individually; however, the combined AuNP-chitosan suspension and Fe(0)-hydrogel DGT did not provide quantitative nitrate concentrations. Further research is required to improve the reaction rate of the AuNP-chitosan nitrite-binding layer, to meet the requirement of rapid binding to operate as a DGT.

Improved stability and film formability of oil-based silver nanoparticle suspensions by addition of polystyrene

In this study, we focused on how to develop an oil-based stable suspension of conductive silver ink and improve its film formability on the substrate. Silver nanoparticles (Ag-NPs) were first prepared in water with addition of oleic acid (OA) and butyl amine (BA) as co-stabilizing agents. The water medium was then replaced by an organic solvent to prepare the organic silver conductive ink. The synthesized Ag-NPs with an average particle size of about 13.3 nm were stabilized by steric hindrance of the attached OA− as proved by FTIR analysis and surface zeta potential. The Ag-NPs had higher stability in cyclohexane than in hexane, owing to the increased interaction between the long alkyl chain in OA− and cyclohexane. The stability was more than one year in cyclohexane with little change in particle size. Conductive films were obtained by drop-coating the organic Ag-NP inks on glass slide and sintering up to 250 °C. Moreover, addition of polystyrene at 1 wt % into the cyclohexane increased the wettability of conductive ink on the substrate and improved the film formability and integrity while preventing oxidation during sintering. A uniform and hydrophobic Ag-NP film was obtained with a sheet resistance of 0.64 Ω/Sq.

Minimizing the Silver Free Ion Content in Starch Coated Silver Nanoparticle Suspensions with Exchange Cationic Resins.

This work describes the optimization of a methodology for the reduction of silver ions from silver nanoparticle suspensions obtained from low-yield laboratory procedures. The laboratory synthesis of silver nanoparticles following a bottom-up approach starting from silver nitrate, originates silver ions that were not reduced to their fundamental state for nanoparticles creation at the end of the process. However, it is well known that silver ions can easily influence chemical assays due to their chemical reactivity properties and can limit biological assays since they interfere with several biological processes, namely intracellular ones, leading to the death of living cells or organisms. As such, the presence of silver ions is highly undesirable when conducting biological assays to evaluate the influence of silver nanoparticles. We report the development of an easy, low-cost, and rapid methodology that is based on cation exchange resins to minimize the silver ion content in a raw suspension of silver nanoparticles while preserving the integrity of the nanomaterials. This procedure preserves the physical-chemical properties of the nanoparticles, thus allowing the purified nanoparticulate systems to be biologically tested. Different types of cationic resins were tested, and the developed methodology was optimized by changing several parameters. A reduction from 92% to 10% of free silver/total silver ratio was achieved when using the Bio-Rad 50W-X8 100–200 mesh resin and a contact time of 15 min. Filtration by vacuum was used to separate the used resin from the nanoparticles suspension, allowing it to be further reused, as well as the purified AgNPs suspension.

Solid-contact potentiometric sensors based on silver nanoparticles in the supramolecular matrix for the determination of halogenide ions

Determination of halogenide ions in pharmaceuticals and various waters is an actual task for the modern analytical chemistry. In the current work, solid-contact potentiometric sensor, based on the glassy carbon electrode covered with the layer of electropolymerized polyaniline and suspension of silver nanoparticles in the matrix of thiacalix[4]arene derivative bearing terminal catechol groups, has been described. The suspension was obtained by the chemical reduction of silver ions with the thiacalix[4]arene and drop casted on the polyaniline layer. The sensor showed potentiometric response to chloride-, bromide and iodide ions. For the simultaneous determination of iodide and bromide ions, a multi-sensor system, consisting of four electrodes with the different volumes of the suspension placed on the polyaniline layer, has been developed. The possibility of the response prediction within the simple additive model was found for the set of the iodide and bromide mixtures. In a similar manner, simultaneous determination of both ions in the variable mixtures has been performed. The multi-sensor system was tested during the determination of iodides in iodine containing pharmaceuticals and the determination of iodide and bromide ions in the artificial mineral water samples. Ionic chromatography was chosen as the comparison method. Sensors made it possible to determine from 0.1 μM to10 mMiodide and bromide ions in mixtures. The proposed approach and solid-contact potentiometric sensors can be used in the analysis of ion content of the waters and in control of the production and storage conditions of pharmaceuticals.