Size Distribution Of AgNPs Research Articles

Synthesis of Silver Nanoparticles from Extract of Epiphytic Shrub Leaves (Ficus heteropleura Blume) on Oil Palm Plant and Evaluation of Their Antibacterial Activity Against Escherichia coli

Silver nanoparticles are silver metal particles with a size of less than 100 nm. Extract of epiphytic shrub leaves (Ficus heteropleura Blume) serves as a bioreductant in producing silver nanoparticles, which are utilized for their antibacterial properties against Escherichia coli. This study aims to synthesize silver nanoparticles and assess their activity against Escherichia coli. Silver nanoparticles (AgNPs) were synthesized using the green synthesis method with Ficus heteropleura leaf extract with silver nitrate (AgNO3). AgNPs were synthesized using a 1 mM solution of AgNO3 and different concentrations (2, 4, 6, 8, and 10%) of Ficus heteropleura extract. The AgNPs were characterized using UV-Vis spectrophotometer, FTIR, and PSA. UV-Vis analysis revealed that AgNPs at concentrations ranging from 2% to 10% exhibited absorbance peaks within the wavelength range of 201.2–473.5 nm. FTIR analysis identified functional groups such as OH, CH, C=C, C≡C, C≡N, and CO, which played a role in reducing silver nanoparticles. The size distribution of AgNPs was determined, with AgNPs synthesized at a concentration of 6% exhibiting a size range of 1–100 nm, constituting 40.77% of the total. For AgNPs synthesized at concentrations of 8% and 10%, the percentage of nanoparticles in the 1–100 nm size range was found to be 26.845% and 1.28%, respectively. The antibacterial activity of AgNPs at concentrations of 6% and 8% against Escherichia coli demonstrated moderate effectiveness.

Radiation preparation and antimicrobial activity of Poly(PVA/starch/Ag NPs) nanocomposite towards Penicillium digitatum on citrus fruits

The synthesis of Poly(PVA/St/Ag NPs) nanocomposite by using of gamma radiation was carried out. The progress of the reaction was examined by using different techniques such as Fourier transform infrared (FTIR), transmission electron microscopy (TEM), UV, XRD, and scanning electron microscopy (SEM). The FTIR show the successful preparation of the Poly(PVA/St/Ag NPs) nanocomposite by gamma radiation at a dose of 5 kGy. The TEM analysis displays the particle size distribution of Ag NPs and it is observed that the Ag NPs size was in the range of 21-30 nm. The SEM images show a good distribution of silver nanoparticles in the Poly(PVA/St/Ag NPs) nanocomposite. matrix, but with little agglomerations or aggregates observed on the surface of the Poly(PVA/St/Ag NPs) nanocomposite. The XRD analysis indicates that amorphous regions are enhanced in the Poly(PVA/St/Ag NPs) nanocomposite. The coating of Citrus fruits by of Poly(PVA/St/Ag NPs) nanocomposite showed better performance in inhibition of the growth of P. digitatum on citrus fruits than free Ag NPs at concentration of 30 ppm. The incorporation of Ag NPs in Poly(PVA/St/Ag NPs) nanocomposite has extremely obvious antifungal activities against P. digitatum due to the nanometer range of Ag NPs that can interact with P. digitatum surface and/or its core where it enters inside the cell, as a result, cellular metabolism is inhibited causing death of P. digitatum and subsequently exhibits antifungal activities.

Antimicrobial and antioxidant activity of AgNPs stabilized with Calendula officinalis flower extract

The present research is devoted to optimizing the green synthesis technology of silver nanoparticles (AgNP) with antibacterial properties for further external use. Standardized marigold flowers extract was utilized as reducing and stabilizing agent, which has significantly richer composition of phytochemical groups compared to its aqueous extracts. A comparative analysis of the physicochemical properties and sedimentation stability of AgNPs obtained by exposure of the reaction mixture to: UV radiation, microwave radiation and high temperature using UV–Vis spectrophotometry and Zeta potential analysis were carried out. pH effect of the reaction mixture on size distribution of AgNPs was evaluated. A good stability of AgNPs to aggregation was observed for samples generated under ultraviolet irradiation with continuous stirring. The particle size distribution obtained by UV irradiation with an average size of 80 nm and PDI 0.26. The storage of AgNPs at 4 °C resulted in some aggregation of small size AgNPs that led to the increase the absorbance at 430 nm. Thus, after one month of storage there was no following increase of the absorbance and there was non-significant aggregation over 3 months’ study. Antibacterial activity of AgNPs against S. aureus and E. coli was estimated with and without light irradiation (445 and 635 nm, 14 W). Additionally, the antioxidant activity of the plant extract and the AgNPs stabilized by the extract was estimated.

Toxicokinetics and Particle Number-Based Trophic Transfer of a Metallic Nanoparticle Mixture in a Terrestrial Food Chain.

Herein, we investigated to which extent metallic nanoparticles (MNPs) affect the trophic transfer of other coexisting MNPs from lettuce to terrestrial snails and the associated tissue-specific distribution using toxicokinetic (TK) modeling and single-particle inductively coupled plasma mass spectrometry. During a period of 22 days, snails were fed with lettuce leaves that were root exposed to AgNO3 (0.05 mg/L), AgNPs (0.75 mg/L), TiO2NPs (200 mg/L), and a mixture of AgNPs and TiO2NPs (equivalent doses as for single NPs). The uptake rate constants (ku) were 0.08 and 0.11 kg leaves/kg snail/d for Ag and 1.63 and 1.79 kg leaves/kg snail/d for Ti in snails fed with NPs single- and mixture-exposed lettuce, respectively. The elimination rate constants (ke) of Ag in snails exposed to single AgNPs and mixed AgNPs were comparable to the corresponding ku, while the ke for Ti were lower than the corresponding ku. As a result, single TiO2NP treatments as well as exposure to mixtures containing TiO2NPs induced significant biomagnification from lettuce to snails with kinetic trophic transfer factors (TTFk) of 7.99 and 6.46. The TTFk of Ag in the single AgNPs treatment (1.15 kg leaves/kg snail) was significantly greater than the TTFk in the mixture treatment (0.85 kg leaves/kg snail), while the fraction of Ag remaining in the body of snails after AgNPs exposure (36%) was lower than the Ag fraction remaining after mixture exposure (50%). These results indicated that the presence of TiO2NPs inhibited the trophic transfer of AgNPs from lettuce to snails but enhanced the retention of AgNPs in snails. Biomagnification of AgNPs from lettuce to snails was observed in an AgNPs single treatment using AgNPs number as the dose metric, which was reflected by the particle number-based TTFs of AgNPs in snails (1.67, i.e., higher than 1). The size distribution of AgNPs was shifted across the lettuce-snail food chain. By making use of particle-specific measurements and fitting TK processes, this research provides important implications for potential risks associated with the trophic transfer of MNP mixtures.

Sustainable-Green Synthesis of Silver Nanoparticles Using Aqueous Hyssopus officinalis and Calendula officinalis Extracts and Their Antioxidant and Antibacterial Activities.

Silver nanoparticles (AgNPs) biosynthesized using aqueous medical plant extracts as reducing and capping agents show multiple applicability for bacterial problems. The aim of this study was to expand the boundaries on AgNPs using a novel, low-toxicity, and cost-effective alternative and green approach to the biosynthesis of metallic NPs using Calendula officinalis (Calendula) and Hyssopus officinalis (Hyssopus) aqueous extracts. The formation of AgNPs was confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) techniques. The effectiveness of biosynthesized AgNPs in quenching free radicals and inhibiting the growth of Gram-positive and Gram-negative microorganisms was supported by in vitro antioxidant activity assay methods and using the Kirby-Bauer disk diffusion susceptibility test, respectively. The elucidated antimicrobial and antioxidative activities of medical plant extracts were compared with data from the engineered biosynthetic AgNPs. The antimicrobial effect of engineered AgNPs against selected test cultures was found to be substantially stronger than for plant extracts used for their synthesis. The analysis of AgNPs by TEM revealed the presence of spherical-shaped nano-objects. The size distribution of AgNPs was found to be plant-type-dependent. The smaller AgNPs were obtained with Hyssopus extract (with a size range of 16.8 ± 5.8 nm compared to 35.7 ± 4.8 nm from Calendula AgNPs). The AgNPs' presumably inherited biological functions of Hyssopus and Calendula medical plants can provide a platform to combat pathogenic bacteria in the era of multi-drug resistance.

Fabrication of flower-like Ag/lignin composites and application in antibacterial fabrics

The bacterial infection and its transmission pose a great threat to life and health, which leads to the urgent development of efficient and broad-spectrum antibacterial agents. Herein, Ag/lignin layered nanoflower (Ag/EHL-CM-0.05) was synthesized by using biomass lignin as reducing and capping agents and silver nitrate as precursor. The study showed that the size distribution of Ag NPs was uniform distribution and about 20–40 nm. The crystal surface of Ag NPs was Ag (111) surface. The minimum inhibitory concentration of Ag/EHL-CM-0.05 against E. coli and S. aureus was all 7.8 μg/mL, which was the lowest of other Ag/lignin antibacterial materials and reached a level nearly as polycationic antibacterial agents. The antibacterial mechanism suggested that Ag/EHL-CM-0.05 could release OH and Ag+, which could cause bacterial death. Finally, Ag/EHL-CM-0.05 was sprayed onto the viscose fabrics by liquid-phase spray deposition method. It was found that the inhibition zone diameter of modified viscose fabrics against E. coli and S. aureus only dropped about 0.16 cm on average after friction treatment and 0.32 cm on average after washing treatment. This work provides a new idea for the design and synthesize of efficient, broad-spectrum, and bio-compatible antibacterial agents, which has important social, economic, and environmental significance.

Effect of Laser Parameters on the Characteristics and Stability of Ag NPs Produced by Laser Ablation in Stationary Conditions

The effect of laser ablation parameters on the size and stability of synthesized silver nanoparticles (Ag NPs) by laser ablation in deionised water was investigated. The results showed that the selected laser parameters (laser pulse wavelength and laser fluence) and ablation of the target in a fixed beam position had a direct effect on the size and size distribution of Ag NPs. The stability of all Ag nanoparticle samples prepared in different laser parameters has been studied. All the samples of Ag NPs presented remarkable long-term stability up to two months.

Biogenically proficient synthesis and characterization of silver nanoparticles (Ag-NPs) employing aqueous extract of Aquilegia pubiflora along with their in vitro antimicrobial, anti-cancer and other biological applications

Aquilegia pubiflora leaves are reported against hepatitis, for treatment of skin burns, wound healing, jaundice, gynea, circulatory and cardiovascular disease in several studies. Therefore, green synthesis of silver nanoparticles with A. pubiflora leaves extract, as an alternative to chemical synthesis, is beneficial from its biological applications point of view. The formation and size distribution of Ag-NPs were confirmed by UV-spectroscopy, Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Transmission electron microscopy (TEM), Energy Dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR) and HPLC. Silver nanoparticles with a particle size of 19 nm were used in various assays including antimicrobial, antioxidant, anti-Alzheimer, anti-diabetic, anti-aging, anti-cancer and biocompatibility studies. Our findings revealed that A. pubiflora mediated Ag-NPs were highly active against both bacterial and fungal strains with Escherichia coli and Aspergillus niger displaying the highest zone of inhibition 10.9 ± 0.29 mm and 13.11 ± 0.33 mm respectively. Dose dependent cytotoxic activity was shown by NPs against Leishmania Tropica with significant IC50 of 175 μg/mL for promastigote and 169 μg/mL for amastigote forms. The Ag-NPs proved to be highly toxic for the HepG2 cell line and inhibit cell viability up to 52.06 ± 2.9% after 24 h of Ag-NPs treatment. Ag-NPs also showed excellent inhibitory potential against the enzymes acetylcholinesterase (AChE: 71.38 ± 1.75) and butyrylcholinesterase (BChE: 73.61 ± 1.96) which are involved in Alzheimer's disease. Overall, the enzymes involved in aging, diabetes, and inflammation showed a moderate inhibitory response to Ag-NPs, led to the conclusion that they are a promising choice for various biological applications.

Microplasma assisted synthesis of silver nanoparticles capped with PVA, PVP and Sucrose

Silver nanoparticles (Ag NPs) have been synthesized by exposing Ar gas microplasma to liquid solution containing Ag+ ions. Sucrose, Polyvinyl Alcohol (PVA) and Polyvinylpyrrolidone (PVP) were added separately as capping agents in aqueous solution to avoid agglomeration of Ag NPs. There are two main mechanism involved in this experiment (1). interaction of electrons from microplasma with Ag+ ions present in aqueous solution and (2). Control of Ag NPs size by capping agents by surrounding Ag NPs. We have performed a comparison of capping performance of Sucrose and PVA in terms of stability of Ag NPs with the help of Ultraviolet-Visible spectroscopy (UV-vis). X-ray diffraction (XRD) analysis of Ag NPs capped with PVA and Sucrose shows average crystal size of 25 nm and 60 nm respectively. Dynamic Light Scattering (DLS) analysis was employed to measure the size distribution of Ag NPs capped with Sucrose, PVA and PVP capping agents. DLS showed that PVA-capped Ag NPs formed are more uniform in size as compared to Sucrose-capped. Average size of Ag NPs measured from DLS is 65 nm when capped with PVA and 120 nm when capped with Sucrose. Fourier Transform Infrared Spectroscopy (FTIR) spectrum obtained have bands of wavenumbers corresponding to functional groups of Sucrose and PVA which are present around Ag NPs.

Characterization of nanoparticles using coupled gel immobilization and label-free optical imaging.

Accurate quantification of number concentration of nanoparticles (NPs) is critical for their biomedical and catalytic applications. We developed a novel NP analysis platform based on coupled gel immobilization and a three-dimensional (3D) scattered light imaging (SLI) platform. This imaging-based technique enables high-throughput analysis of silver nanoparticles (AgNPs) at single-particle level without the need for particle labeling or modification. This is a well-established quantitative characterization technique that can simultaneously measure the number concentration and size distribution of AgNPs. It also demonstrates the visualization and quantification of the size and 3D morphology of AgNP agglomerates in solution.

A single-step fabrication of Ag nanoparticles and CVD graphene hybrid nanostructure as SERS substrate

Functionalization and modification of chemical vapor deposition (CVD) growth graphene are crucial to develop new surface-enhanced Raman scattering (SERS) substrate for practical applications. In this study, a hybrid nanostructure of AgNPs@G was designed considering taking advantage of both the electromagnetic enhancement mechanism (EM) and chemical enhancement mechanism (CM) thanks to AgNPs and CVD growth graphene via a single-step fabrication. The size distribution of AgNPs with a perfect single crystalline structure obtained as 2–10 nm and uniformly decorated on CVD graphene surface. The excellent integration of AgNPs and graphene has been confirmed by TEM and XPS studies. The SERS activity of the fabricated AgNPs@G nanocomposite has been examined using Rhodamine 6G (R6G) as a probe molecule with different concentrations. The value of enhancement factor (EF) calculated as 7.2 × 104 suggests that the AgNPs@G nanostructure substrates have perfect SERS properties. The results in this paper demonstrate that the fabricated hybrid nanostructure AgNPs@G can be promising SERS substrate in many practical applications.

Microwave-irradiated green synthesis of metallic silver and copper nanoparticles using fresh ginger (Zingiber officinale) rhizome extract and evaluation of their antibacterial potentials and cytotoxicity

Herein the microwave-assisted green synthesis of both silver (Ag) and copper (Cu) nanoparticles (NPs) by microwave irradiation have been successfully carried out using fresh ginger rhizome extract. Different analytical methods were used for the characterization of the nanoparticles. The size distribution of AgNPs was found from the range of 2.68 nm to 42.69 nm, whereas for CuNPs the size range was run from 11.32 nm to 33.70 nm in diameter. From the antibacterial assay, we found that both silver and copper nanoparticles demonstrated significant potentials against tested bacterial strains. Besides, in vitro cytotoxic effects of NPs were also tested on the L929 mouse fibroblast cell line through XTT cell viability assay which confirmed the non-toxic nature of AgNPs and CuNPs at all tested concentrations. Thus, the obtained biological properties, suggested the use of rhizome extract of Zingiber officinale mediated non-toxic AgNPs and CuNPs in further biomedical and clinical applications.

Shape memory hybrid based on polyvinyl alcohol and 0D silver nanoparticles

Shape memory hybrids (SMH) have drawn significant attention because they allow an easy alternative for the design of shape memory materials with tailored properties or features. In this work, a shape memory hybrid was made, based on polyvinyl alcohol (PVA) as the elastic domain and 0D silver nanoparticles (Agnps) as the transition domain, a dissolution method of mixing both components, and evaporation of water afterward allowed the formation of films of the hybrid material. Two different size distributions of silver nanoparticles were used (13.7 ± 2.6 and 67.9 ± 14.1 nm), in order to study the effect of the size on the shape memory effect (SME) of the final SMH, under temperature stimuli. The materials obtained were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy, infrared spectroscopy (IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. The crystallinity of PVA was slightly altered with the addition of Agnps. Finally, the shape memory effect was tested on both hybrid materials, resulting in a better response to temperature for the SMH prepared with Agnps of 68 nm, also the shape recovery time can be tuned varying both the increase of temperature and the size distribution of Agnps used.

Impact of in vitro digestion on gastrointestinal fate and uptake of silver nanoparticles with different surface modifications

Nanomaterials, especially silver nanoparticles (AgNPs), are used in a broad range of products owing to their antimicrobial potential. Oral ingestion is considered as a main exposure route to AgNPs. This study aimed to investigate the impact of the biochemical conditions within the human digestive tract on the intestinal fate of AgNPs across an intestinal in vitro model of differentiated Caco-2/HT29-MTX cells. The co-culture model was exposed to different concentrations (250–2500 µg/L) of pristine and in vitro digested (IVD) AgNPs and silver nitrate for 24 h. ICP-MS and spICP-MS measurements were performed for quantification of total Ag and AgNPs. The AgNPs size distribution, dissolution, and particle concentration (mass- and number-based) were characterized in the cell fraction and in the apical and basolateral compartments of the monolayer cultures. A significant fraction of the AgNPs dissolved (86–92% and 48–70%) during the digestion. Cellular exposure to increasing concentrations of pristine or IVD AgNPs resulted in a concentration dependent increase of total Ag and AgNPs content in the cellular fractions. The cellular concentrations were significantly lower following exposure to IVD AgNPs compared to the pristine AgNPs. Transport of silver as either total Ag or AgNPs was limited (<0.1%) following exposure to pristine and IVD AgNPs. We conclude that the surface chemistry of AgNPs and their digestion influence their dissolution properties, uptake/association with the Caco-2/HT29-MTX monolayer. This highlights the need to take in vitro digestion into account when studying nanoparticle toxicokinetics and toxicodynamics in cellular in vitro model systems.

Hierarchical Laser-Patterned Silver/Graphene Oxide Hybrid SERS Sensor for Explosive Detection.

We demonstrate an ultrafast laser-ablated hierarchically patterned silver nanoparticle/graphene oxide (AgNP/GO) hybrid surface-enhanced Raman scattering (SERS) substrate for highly sensitive and reproducible detection of an explosive marker 2,4-dinitrotoluene (2,4-DNT). A hierarchical laser-patterned silver sheet (Ag–S) is achieved by ultrafast laser ablation in air with pulse energies of 25, 50, and 100 μJ. Multiple laser pulses at a wavelength of 800 nm and a pulse repetition rate of 50 fs at 1 kHz are directly focused on Ag–S to produce and deposit AgNPs onto Ag–S. The surface morphology of ablated Ag–S was evaluated using atomic force microscopy, optical profilometry, and field emission scanning electron microscopy (FESEM). A rapid increase in the ablation rate with increasing laser energy was observed. Selected area Raman mapping is performed to understand the intensity and size distribution of AgNPs on Ag–S. Further, GO was spin-coated onto the AgNPs produced by ultrafast ablation on Ag–S. The hierarchical laser-patterned AgNP/GO hybrid structure was characterized using FESEM, high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. Further, hierarchical laser-patterned AgNP/GO hybrid structures have been utilized as SERS-active substrates for the selective detection of 2,4-DNT, an explosive marker. The developed SERS-active sensor shows good stability and high sensitivity up to picomolar (pM) concentration range with a Raman intensity enhancement of ∼1010 for 2,4-DNT. The realized enhancement of SERS intensity is due to the cumulative effect of GO coated on Ag–S as a proactive layer and AgNPs produced by ultrafast ablation.

Biosynthesized silver nanoparticles for inhibition of antibacterial resistance and biofilm formation of methicillin-resistant coagulase negative Staphylococci

The ability of a natural stabilizing and reducing agent on the synthesis of silver nanoparticles (Ag NPs) was explored using a rapid and single-pot biological reduction method using Nocardiopsis sp. GRG1 (KT235640) biomass. The UV–visible spectral analysis of Ag NPs was found to show a maximum absorption peak located at a wavelength position of ∼422 nm for initial conformation. The major peaks in the XRD pattern were found to be in excellent agreement with the standard values of metallic Ag NPs. No other peaks of impurity phases were observed. The morphology of Ag NPs was confirmed through TEM observation, demonstrating that the particle size distribution of Ag NPs entrenched in spherical particles is in a range between 20 and 50 nm. AFM analysis further supported the nanosized morphology of the synthesized Ag NPs and allowed quantifying the Ag NPs surface roughness. The synthesized Ag NPs showed significant antibacterial and antibiofilm activity against biofilm positive methicillin-resistant coagulase negative Staphylococci (MR-CoNS), which were isolated from urinary tract infection as determined by spectroscopic methods in the concentration range of 5–60 µg/ml. The inhibition of biofilm formation with coloring stain was morphologically imaged by confocal laser scanning microscopy (CLSM). Morphological alteration of treated bacteria was observed by SEM analysis. The results clearly indicate that these biologically synthesized Ag NPs could provide a safer alternative to conventional antibiofilm agents against uropathogen of MR-CoNS.

Synthesis of soy protein/polyacrylamide nanocomposite hydrogels for delivery of ciprofloxacin drug

Now a day, silver nanoparticles (AgNps) have attracted considerable attention in various biomedical applications like drug delivery, photo thermal ablation of cancer and imaging agent for cancer diagnosis. The present work is demonstrated on the nano silver embedded soy protein polyacrylamide (PAM-SP@Ag) nanocomposite hydrogel which is synthesized by in situ polymerization process for the release of ciprofloxacin drugs. The structure and morphology of the nanocomposite hydrogels have been explored using FTIR, XRD, XPS, and FESEM analysis. It is found that, the average size of AgNps is 50 nm whereas; size distributions of AgNps are studied from DLS study. The investigation of the release rate of ciprofloxacin drugs carried out by measuring water retention and swelling properties of nanocomposite hydrogels. The in vitro ciprofloxacin drug release rate is noticed to be 95.3% in a time period of 6hr. The investigation of cytotoxicity tests and antibacterial behaviour along with negative and positive action of nanocomposite hydrogels are studied. The gelling actions of prepared nanocomposite hydrogels are given by the rheological study. The cytotoxicity behaviour of PAM-SP@Ag nanocomposite hydrogels along with improved swellings and rheological properties are enabling the material as suitable vehicle for safe release of ciprofloxacin drug.

Eco-friendly walnut shell powder based facile fabrication of biogenic Ag-nanodisks, and their interaction with bovine serum albumin

Walnut shell biomass was used for the extraction of juglone by water as a solvent at room temperature. Upon addition of AgNO3 to a dye solution, prefect transparent pale brown color develops within the reaction time. UV–visible spectroscopy revealed the appearance of surface plasmon absorption (SRP) peak at 410 nm for spherical silver nanoparticles (AgNPs). Transmission electron microscopy suggested the formation of spherical and truncated triangular nano-plate geometry of AgNPs with average diameter 25 nm. Juglone-surfactant interactions (micellization and incorporation) have been studied spectrophotometrically by using cationic cetyltrimethylammonium bromide (CTAB). The presence of CTAB has significant impacts on size, shape and the size distribution of AgNPs. The nucleation, growth, and adsorption processes depend on the [CTAB]. It also catalyzes the Ag+ ions reduction by juglone with a rate enhancement of ca. 100-fold. Activation parameters (activation energy, enthalpy of activation and entropy of activation) were evaluated to the synthesis of silver nano-disks. Antioxidant activity of juglone was accessed by the scavenging effect on DPPH radical. Silver nanoparticles was also used as quencher to determine their interaction with bovine serum albumin (BSA). The quenching constant were found to be 1.4 × 103 M−1 L s−1 and 4.8 × 103 M−1 L s−1 for two BSA concentrations.

Silver nanoparticles assessment in moisturizing creams by ultrasound assisted extraction followed by sp-ICP-MS

Advances on nanometrology require reliable sample pre-treatment methods for extracting/isolating nanomaterials from complex samples. The current development deals with a discontinuous ultrasonication (60% amplitude, 15 cycles of ultrasound treatment for 59 s plus relaxing stage for 59 s, 20 mL of methanol) method for a fast and quantitative extraction of silver nanoparticles (Ag NPs) from moisturizing creams. Possibilities offered by modern inductively coupled plasma mass spectrometry (ICP-MS) which allow ‘single particle’ assessment (sp-ICP-MS) have been used for Ag NPs assessment (Ag NPs concentration and Ag size distribution). The relative standard deviation (RSD) of the over-all procedure (Ag NPs concentration in eleven extracts from a same cream) was found to be 5%; whereas, the analytical recovery for spiking experiments with Ag NPs of 20, 40, and 60 nm was found to be within the 90–109% range. The limit of quantification in Ag NPs concentration was established at 8.25 × 105 Ag NPs g−1; whereas, the limit of detection in size was found to be within the 5–13 nm (several equations were used for calculation). Finally, moisturizing creams prescribed for atopic dermatitis and also regular moisturizing creams were analyzed for total Ag, and for Ag NPs characterization (Ag NPs concentration and Ag NPs size distribution) by sp-ICP-MS. Electronic microscopy was also used for comparative (qualitative) purposes.

Peripherally functionalized based dendrimers as the template for synthesis of silver nanoparticles and investigation the affecting factors on their properties

Today, dendrimers (D) were introduced as a versatile template for the synthesis of nanoparticles (NPs). In this work, the stable silver nanoparticles (AgNPs) is successfully synthesized through the chemical reduction of AgNO3 using NaBH4 as a reducing agent. Synthesis of AgNPs was performed in the presence of different generations of citric acid-based dendrimers (G1, G2 and G3) and hydroxyl-terminated citric acid-based dendrimers (G1-OH, G2-OH and G3-OH). High-resolution transmission electron microscopy, electron diffraction and energy-dispersive X-ray analysis were used to characterize the synthesized AgNPs. UV–Vis results were used for the qualitative study of the synthesized AgNPs properties. With varying the molar ratio of dendrimer/Ag+, generations of dendrimers and the pH of the solution, the size and size distribution of AgNPs could be easily controlled at room temperature. The average diameter of the synthesized AgNPs in the presence of Gn-OH was in the range of 8–20 nm. Results show that G1-OH alkaline medium with 1:1 molar ratio of D/Ag is the optimum condition for the synthesis of AgNPs. All the obtained results from this study showed that controlling the medium conditions allows AgNPs with the desired size to be obtained.