Preparation of amine coated silver nanoparticles using triethylenetetramine

Synthesis of silver nanoparticles for use in conductive inks by chemical reduction method

In this study, the chemical reduction method was applied to synthesize silver nanoparticles used to prepare conductive inks. The two variables of polyvinylpyrrolidone (PVP)-stabilized mole in the 0.01-0.03 mol range and hydrazine reducing mole in the 0.1-0.5 mol range, along with constants such as precursor mole (silver nitrate), complexing mole (ethylene diamine) and solvent mole (water), were used. Nine random samples proposed by the Design Expert software were examined and studied. X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS) were then used to characterize and evaluate the synthesized nanoparticles. According to the results obtained by XRD, FE-SEM and TEM analyses, the sample with 0.025 mol and 0.3 mol PVP had the minimum size of silver nanoparticles, which was around 20 nm, so it was chosen as the optimal sample for further research. The conductive ink was also prepared with the optimal sample of silver nanoparticles in 40% by weight and then characterized and evaluated by applying ultraviolet-visible (UV-Vis), simultaneous thermal analysis (STA), FE-SEM and electrical conductivity analysis. Finally, conductive ink was applied to polyethylene terephthalate (PET) and acrylonitrile butadiene styrene (ABS) substrates. The surface electrical resistance of conductive ink on PET and ABS substrates was then measured at about 6.4 Ω and 2.2 Ω, respectively.

Antimicrobial activity of silver salt and silver nanoparticles in different forms against microorganisms of different taxonomic groups

The development of antiseptics and medical products (bandaging materials, sponges, etc.) based on silver nanoparticles is an essential task due to the growing resistance of pathogenic microorganisms to medicines long used in clinical practice. Using silver nanoparticles for the same purpose is promising, but the potential hazards and cumulative effects in the application of nanoparticles requires a thorough study of those materials. To evaluate the efficiency of antiseptics and medical products based on silver nanoparticles, it is necessary to conduct an in-depth study of the activity of silver nanoparticles in different forms and immobilized in carriers. The study examines the resistance of bacterial and fungal cultures to silver nanoparticles produced by chemical reduction and microbiological synthesis. The study of resistance was carried out in different growth phases of pathogenic microorganisms and in both liquid and solid media. Chemically and microbiologically synthesized nanoparticles were added in the form of a suspension, as well as encapsulated in chitosan-PVA matrices. It was experimentally discovered that, depending on the medium and form of the silver, the antibacterial effect would significantly differ due to changes in the mechanisms regarding the release of nanoparticles and their activity against the cells of pathogenic and potentially pathogenic microorganisms.

Mechanisms of Cu2+, triethylenetetramine (TETA), and Cu-TETA sorption on rectorite and its use for metal removal via metal-TETA complexation

Uptake of metals, organics, and formation of metal-organic complexes on the surface or in the interlayer of clay minerals had been studied extensively over the last half century. In this study, we investigated the uptake mechanisms of Cu²⁺, triethylenetetramine (TETA), and Cu-TETA on rectorite and its use for metal removal via metal-TETA complexation. The uptake of Cu²⁺, TETA, and Cu-TETA by rectorite occurred on the external as well as in the interlayer space, resulting in a change of d₀₀₁-spacing due to differences in sizes of interlayer cations or complexes. Although the uptake of Cu²⁺ and Cu-TETA by rectorite was via a cation exchange process as evidenced by the stoichiometric desorption of dominant interlayer cation Ca²⁺, the uptake of TETA alone on rectorite was via complexation with interlayer cation Ca²⁺. Due to strong affinity of TETA for Cu²⁺, significant amounts of Cu²⁺ uptake occurred on TETA-rectorite. Desorption of Ca²⁺ from TETA-rectorite confirmed the replacement of interlayer cation Ca²⁺ by Cu²⁺. However, the replacement of Ca²⁺ by Cu²⁺ in TETA-rectorite did not involved in removal of TETA. As such, TETA-modified clay minerals may serve as a type of sorbents for the removal of selected heavy metals via surface or interlayer via complexation.

Ranolazine-Functionalized Copper Nanoparticles as a Colorimetric Sensor for Trace Level Detection of As3

This study involves environmentally friendly synthesis of copper nanoparticles in aqueous medium without inert gas protection, using ranolazine as a capping material. UV-Visible (UV-Vis) spectrometry showed that ranolazine-derived copper nanoparticles (Rano-Cu NPs) demonstrate a localized surface plasmon resonance (LSPR) band at 573 nm with brick-red color under optimized parameters, including pH, reaction time, and concentrations of copper salt, hydrazine hydrate, and ranolazine. The coating of ranolazine on the surface of Cu NPs was studied via Fourier transform infrared (FTIR) spectroscopy. Scanning electron microscopy (SEM) revealed that Rano-Cu NPs consist of spherical particles. X-ray diffraction (XRD) verified that Rano-Cu NPs are crystalline in nature. Atomic force microscopy (AFM) showed that the average size of Rano-Cu NPs was 40 ± 2 nm in the range of 22⁻95 nm. Rano-Cu NPs proved to be highly sensitive as a selective colorimetric sensor for As³⁺ via color change from brick red to dark green, in the linear range of 3.0 × 10^-7 to 8.3 × 10^-6 M, with an R² value of 0.9979. The developed sensor is simple, cost effective, highly sensitive, and extremely selective for As³⁺ detection, showing a low detection limit (LDL) of 1.6 × 10^-8 M. The developed sensor was effectively tested for detection of As³⁺ in some water samples.

Ultrasound-assisted extraction of antimicrobial compounds from Thymus daenensis and Silybum marianum: Antimicrobial activity with and without the presence of natural silver nanoparticles

The present study is devoted to prepare a new antibacterial and antifungal agent based on in situ-synthesized silver nanoparticles at room temperature using Rosmarinus officinalis (R. officinalis) leaf extract. The Ag-NPs characterization by UV-visible, SEM, TEM and XRD revealed that the particles sizes were in the range of 10-33 nm. In this study, hydroalcoholic extracts were used with ultrasonic method. Ultrasonication has recently received attention as a novel bioprocessing tool for process intensification in many areas of downstream processing. The antimicrobial activities of T. daenensis and S. marianum extracts with and without the presence of Ag-NPs were investigated at concentrations from 12.5 to 50 mg/mL against Staphylococcus aureus (S. aureus, Gram-positive organism) and Escherichia coli (E. coli, Gram-negative organism), and fungal strains were Aspergillus oryzae (A. oryzae) and Candida albicans (C. albicans). Antimicrobial activity determined using agar disc diffusion method revealed that the activities of Ag-NPs/T. daenensis were superior to Ag-NPs/S. marianum and extracts (T. daenensis and S. marianum). The medicinal plant extract can be used to synthesize the Ag-NPs as an eco-friendly and inexpensive method in large scale. The results showed that the prepared Ag-NPs/extracts as good antibacterial and antifungal agents can be potentially applied against rapidly increasing of antibiotic resistance.

Generation of Janus Molecularly Imprinted Polymer Particles

Janus particles, which have two or more distinct physical surfaces, provide a number of potential applications in many fields. However, it is difficult to selectively load chemical or biological components onto the Janus particles. Here, the approach utilizing molecular imprinting and Pickering emulsion technologies for the synthesis of molecularly imprinted polymer (MIP)-based Janus particles (which showed high affinity to the targets) is described stepwise. As self-propelled microengines possessing specific molecular recognition ability, Janus molecularly imprinted polymer particles show high potential for specific and well-controlled drug delivery.

Label free and high specific detection of mercury ions based on silver nano-liposome

Herein, we report an eco-friendly, mild and one-pot approach for synthesis of silver nanoparticles via a lipopeptide biosurfactant - CHBS. The biosurfactant forms liposome vesicles when dispersed in an aqueous medium. The amino acid groups of the biosurfactant assists in the reduction of Ag(+) ions leading to the production of homogeneous silver nanoparticles, encapsulated within the liposome vesicle, as confirmed from TEM analysis. Rate of synthesis and size of particle were greatly dependent on pH and reaction temperature. Kinetic analysis suggests the involvement of an autocatalytic reaction and the observed rate constant (kobs) was found to decrease with temperature, suggesting faster reaction with increasing temperature. Furthermore, the silver nanoparticles served as excellent probes for highly selective and sensitive recognition of Hg(2+) ions. Interaction with Hg(2+) ions results in an immediate change in colour of nanoparticle solution form brownish red to milky white. With increasing Hg(2+) ions concentration, a gradual disappearance of SPR peak was observed. A linear relationship (A420/660) with an R(2) value of 0.97 was observed in the range of 20 to 100ppm Hg(2+) concentration. Hg(2+) ions are reduced to their elemental forms which thereby interact with the vesicles, leading to aggregation and precipitation of particles. The detection method avoids the need of functionalizing ligands and favours Hg(2+) detection in aqueous samples by visible range spectrophotometry and hence can be used for simple and rapid analysis.

Cefuroxime derived copper nanoparticles and their application as a colorimetric sensor for trace level detection of picric acid

Picric acid is used as explosive material in destructive weapons and nuclear technology. Due to higher solubility in water it can create health issues and its monitoring is crucial for safer environment and health.

Synthesis of silver nanoparticles dispersed in various aqueous media using laser ablation

The particle size, morphology, and stability of Ag-NPs were investigated in the present study. A Q-Switched Nd: YAG pulsed laser (λ = 532 nm, 360 mJ/pulse) was used for ablation of a pure Ag plate for 30 min to prepare Ag-NPs in the organic compound such as ethylene glycol (EG) and biopolymer such as chitosan. The media (EG, chitosan) permitted the making of NPs with well dispersed and average size of Ag-NPs in EG is about 22 nm and in chitosan is about 10 nm in spherical form. Particle size, morphology, and stability of NPs were compared with distilled water as a reference. The stability of the samples was studied by measuring UV-visible absorption spectra of samples after one month. The result indicated that the formation efficiency of NPs in chitosan was higher than other media and NPs in chitosan solution were more stable than other media during one month storage. This method for synthesis of silver NPs could be as a green method due to its environmentally friendly nature.

Janus molecularly imprinted polymer particles

Janus MIP particles were synthesized via a wax–water Pickering emulsion. The MIP microtransporter concept provided the Janus MIP particles with attractive capabilities for autonomous binding and controlled drug delivery.

Novel synthesis of silver nanoparticles using 2,3,5,6-tetrakis-(morpholinomethyl) hydroquinone as reducing agent

2,3,5,6-Tetrakis-(morpholinomethyl) hydroquinone (TMMH) was used as a reducing agent to synthesize spherical shaped silver nanoparticles in water-ethanol medium without using any stabilizing and capping agents. The reducing agent TMMH is prepared by Mannich-type reaction method and (1)H NMR, (13)C NMR and FT-IR spectroscopy techniques were used to characterize the compound (TMMH). The nature of bonding, structural and optical properties of the final product were analyzed using different techniques such as UV-Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The interaction between silver and reducing agent was confirmed by using FTIR analysis. The final product obtained showed higher crystallinity with cubic structure and an average crystalline size of about 20 nm. The results revealed that it is possible to synthesize crystalline Ag nanoparticles using organic compound as reducing agent.

Silver nanoparticles as a new solid-phase adsorbent and its application to preconcentration and determination of lead from biological samples

A new, simple, and fast method for preconcentration and determination of trace amount of lead from biological samples was developed by modified silver nanoparticle-based solid-phase extraction technique and graphite furnace atomic absorption spectrometry. In this study, morin was used as a complexing agent. Some factors influencing the recovery of lead including pH, sample flow rate, type, flow rate, and least amount of the eluent for elution of the lead from silver nanoparticles were studied and optimized. Under the optimum conditions, the detection limit of this method was 68 ng L(-1), and the relative standard deviation was 4.1% (n = 10, c = 20 μg L(-1)). The developed procedure was validated by the analysis of certified reference material and applied to the recovery and determination of lead in biological samples.