Physicochemical Properties Of AgNPs Research Articles

Biofabrication of silver nanoparticles with Feijoa sellowiana tailored by box-behnken design: An eco-friendly approach to enhance antifungal properties in Children's toothpaste

Oral candidiasis and its association with dental caries necessitate the development of toothpaste with enhanced antifungal properties, particularly for children at high risk of infection. This study aims to investigate the antifungal efficacy of children's toothpaste incorporating biosynthesized silver nanoparticles (AgNPs) using Feijoa sellowiana. Silver fluoride and Feijoa leaf extract were used for the synthesis of AgNPs. The independent variables were the concentration of AgF, pH of the extract, and temperature. The optimized formula was obtained using Design Expert software and Box-Benken design. The physicochemical properties of AgNPs were evaluated by UV-absorption wavelength measurements, SEM, and TEM analyses. Finally, the powder of optimized AgNPs was added to Colgate Kids Toothpaste® and its antifungal effect was evaluated using the standard agar well diffusion method. The optimization process identified an AgF concentration of 8 mM, a pH value of 9.56, and a temperature of 58 °C as influential factors for the formulation. The optimized AgNPs exhibited a size of 42.75 nm, and SEM and TEM analyses confirmed their spherical shape. Both toothpaste formulations, with and without AgNPs, demonstrated antifungal activity. Although the antifungal effect of both toothpaste types against Candida glabrata did not show a significant difference (p > 0.088), the toothpaste containing AgNPs exhibited significantly higher antifungal efficacy against Candida albicans (p < 0.014). In conclusion, the biosynthesis of silver nanoparticles using silver fluoride and Feijoa leaf extract as an eco-friendly approach can effectively enhance the antifungal potency of toothpaste against C. albicans.

Phyto-Fabrication of Silver Nanoparticles Using Typha azerbaijanensis Aerial Part and Root Extracts.

Silver nanoparticles (AgNPs) were phyto-synthesized using Typha azerbaijanensis aerial part and root extracts, and their biological activities were investigated. This study was conducted in the Science and Research Branch, Islamic Azad University, Tehran, Iran in 2019. In this experimental study, silver nanoparticles (AgNPs) were phyto-synthesized and the physicochemical properties of AgNPs were determined using UV-Vis (UV-Vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. Antibacterial and anticancer activity of synthesized AgNPs was determined using microdilution assay, and MTT 3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) methods, respectively. The apoptotic effects of AgNPs were investigated using Real-Time PCR and flow cytometry techniques. Morphological analysis of the synthesized AgNPs confirmed the spherical shape of AgNPs with an average size of 10.67 to 16.69 nm. The FTIR spectrum confirmed the presence of phytochemicals from T. azerbayenensis extract at the AgNP surface. Antibacterial experiments showed that phyto-fabricated AgNPs had significant antibacterial activity against Gram-negative bacteria. The AgNPs were significantly cytotoxic against breast cancer cell line (MCF-7) through induction of apoptosis. The phyto-synthesized AgNPs had biological activities could be useful in pharmaceutical applications.

Biodirected Synthesis of Silver Nanoparticles Using Aqueous Honey Solutions and Evaluation of Their Antifungal Activity against Pathogenic Candida Spp.

Silver nanoparticles (AgNPs) were synthesized using aqueous honey solutions with a concentration of 2%, 10%, and 20%—AgNPs-H2, AgNPs-H10, and AgNPs-H20. The reaction was conducted at 35 °C and 70 °C. Additionally, nanoparticles obtained with the citrate method (AgNPs-C), while amphotericin B (AmB) and fluconazole were used as controls. The presence and physicochemical properties of AgNPs was affirmed by analyzing the sample with ultraviolet–visible (UV–Vis) and fluorescence spectroscopy, scanning electron microscopy (SEM), and dynamic light scattering (DLS). The 20% honey solution caused an inhibition of the synthesis of nanoparticles at 35 °C. The antifungal activity of the AgNPs was evaluated using opportunistic human fungal pathogens Candida albicans and Candida parapsilosis. The antifungal effect was determined by the minimum inhibitory concentration (MIC) and disc diffusion assay. The highest activity in the MIC tests was observed in the AgNPs-H2 variant. AgNPs-H10 and AgNPs-H20 showed no activity or even stimulated fungal growth. The results of the Kirby–Bauer disc diffusion susceptibility test for C. parapsilosis strains indicated stronger antifungal activity of AgNPs-H than fluconazole. The study demonstrated that the antifungal activity of AgNPs is closely related to the concentration of honey used for the synthesis thereof.

Comparative study of antibacterial inhibitory effect of silver nanoparticles and garlic oil nanoemulsion with their combination

Silver can inhibit bacterial activity. Previous studies showed that high concentration of silver nanoparticles (AgNPs) in compared to its lower concentrations is toxic for human health. However, by decreasing concentration of AgNPs, antibacterial activity also decreases. In this study, we investigated synergistic inhibitory activity of the combination of AgNPs and garlic oil nanoemulsion (GONE) for increase antibacterial activity of AgNPs at lower concentrations. AgNPs and GONE with sizes of 30.7 and 19.3 nm were synthesized and prepared by chemical reduction and low energy method, respectively. Physicochemical properties of AgNPs and GONE were investigated. The minimum inhibitory concentration (MIC) of samples was assessed using the standard microdilution method against pseudomonas aeruginosa and staphylococcus aureus. P. aeruginosa was suspected to AgNPs and GONE at all concentration, but in the case of S. aureus, antibacterial activity was revealed at ≥29.1% (v/v) and ≥ 36.4 ppb concentration of GONE and AgNPs, respectively. In addition, at low concentration, S. aureus was unsuspected to AgNPs and GONE. Combination of AgNPs and GONE (CAG) demonstrated synergistic inhibitory effects at low concentration (≥29.1% (v/v) and ≥ 36.4 ppb concentration). Also, CAG revealed antibacterial activity against S. aureus at low concentration. These results indicate that combination of GONE and AgNPs has potential as a green antiseptic agent.

Silver nanoparticles exert concentration-dependent influences on biofilm development and architecture.

ObjectivesTo investigate the impact of silver nanoparticles (AgNPs) on the biofilm growth and architecture.Materials and methodsSilver nitrate was reduced by d‐maltose to prepare AgNPs in the presence of ammonia and sodium hydroxide. The physicochemical properties of AgNPs were characterized by transmission electron microscopy, ultraviolet‐visible spectroscopy and inductively coupled plasma mass spectrometry. The development of biofilm with and without AgNPs was explored by crystal violet stain. The structures of mature biofilm were visually studied by confocal laser scanning microscopy and scanning electron microscopy. Bacterial cell, polysaccharide and protein within biofilm were assessed quantitatively by colony‐counting method, phenol‐sulphuric acid method and Bradford assay, respectively.ResultsThe spherical AgNPs (about 30 nm) were successfully synthesized. The effect of AgNPs on Pseudomonas aeruginosa biofilm development was concentration‐dependent. Biofilm was more resistant to AgNPs than planktonic cells. Low doses of AgNPs exposure remarkably delayed the growth cycle of biofilm, whereas high concentration (18 μg/mL) of AgNPs fully prevented biofilm development. The analysis of biofilm architecture at the mature stage demonstrated that AgNPs exposure at all concentration led to significant decrease of cell viability within treated biofilms. However, sublethal doses of AgNPs increased the production of both polysaccharide and protein compared to control, which significantly changed the biofilm structure.ConclusionsAgNPs exert concentration‐dependent influences on biofilm development and structure, which provides new insight into the role of concentration played in the interaction between antibacterial nanoparticles and biofilm, especially, an ignored sublethal concentration associated with potential unintended consequences.

Fate and toxicity of silver nanoparticles in freshwater from laboratory to realistic environments: a review.

The fate and risk assessment of silver nanoparticles (Ag NPs) is an important environmental health issue. The toxic effects, mechanisms, and modes of action of Ag NPs on aquatic organisms have been extensively determined in the laboratory. However, knowledge gaps and discrepancies exist between laboratory studies and realistic environmental research; such inconsistencies hinder the development of health and safety regulations. To bridge these gaps, this review summarizes how environmental conditions and the physicochemical properties of Ag NPs affect the inconsistent findings between laboratory studies and realistic environmental research. Moreover, this paper systematically reviews different toxic effects of Ag NPs in a realistic environment and compares these effects with those in the laboratory, which is helpful for assessing the environmental fate and risk of Ag NPs. The hazardous effects of Ag NPs on the whole aquatic ecosystem with low concentrations (μgL-1) and long-term periods (months to years) are detailed. Furthermore, two perspectives of future toxicity studies of Ag NPs in realistic freshwater environments are emphasized.

Influence of gastrointestinal environment on free radical generation of silver nanoparticles and implications for their cytotoxicity

With the increasing number of applications of silver nanoparticles (Ag NPs) in consumer products, including food contact applications, it is important to understand potential health effects of ingestion of Ag NPs. The biosafety analysis of Ag NPs in various mammalian cells has been widely studied; however, the influence of the gastrointestinal environment on the physicochemical properties and toxicity of Ag NPs has not been fully addressed. In the present study, we investigated the impact of simulated human gastrointestinal tract (GIT) fluids on the physicochemical properties of Ag NPs and their impact on the in vitro cytotoxicity of Ag NPs in intestinal epithelial (Caco-2) cells. Polyvinylpyrrolidone (PVP)-coated Ag NPs of different sizes (30, 50, 100 nm) were incubated in three GIT fluids that differed in composition and pH (1.6, 5.0, 6.5) and were designed to mimic human gastric fluid in a fasted state (FaSSGF), human intestinal fluid in a fasted state (FaSSIF), and human intestinal fluid in a fed state (FeSSIF). Time-dependent decreases in UV–Vis absorption and increases in dynamic light scattering (DLS) were observed during the three-hour incubation of Ag NPs in GIT fluids. The results of transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDS) suggested that the Ag NPs aggregated and precipitated as AgCl salts in the presence of FaSSGF and FeSSIF. In the presence of FaSSGF and hydrogen peroxide (H2O2), a particle size- and concentration-dependent generation of hydroxyl radicals (OH) was detected by electron spin resonance (ESR) spectroscopy. When compared to the effects observed with the incubation of Ag NPs in H2O, incubation of Ag NPs in FaSSGF showed decreased cellular uptake in Caco-2 cells. In contrast, the incubation of Ag NPs in FeSSIF demonstrated increased cellular uptake and cytotoxicity. The results of this study demonstrate that GIT fluids have a significant influence on the physicochemical properties and cytotoxicity of Ag NPs and they provide valuable information that may be used in the safety evaluation of Ag NPs for consumer products.

Effects of water chemistry and surface contact on the toxicity of silver nanoparticles to Bacillus subtilis.

The growing use of silver nanoparticles (AgNPs) has created concerns about its potential impacts on natural microbial communities. In this study, the physicochemical properties of AgNPs and its toxicity on natural bacteria Bacillus subtilis (B. subtilis) were investigated in aqueous conditions. The characterization data showed that AgNPs highly aggregated in aqueous conditions, and the hydrodynamic diameter of AgNPs in aqueous conditions was larger than its primary size. The studied AgNPs was less toxic to B. subtilis in estuarine water as compared to that in Milli-Q water and artificial seawater, which might be due to the observed enhanced aggregation of AgNPs in estuarine water. The toxicity of AgNPs to B. subtilis was greatly reduced when their surface contact was blocked by a dialysis membrane. Scanning electron microscope images showed that exposure contact to AgNPs resulted in damage of the microbial cell wall and enhanced formation of fibrillar structures. These results suggest that particle-cell contact is largely responsible for the observed toxicity of AgNPs in B. subtilis. This study can help to understand the potential impacts of AgNPs to natural microbes, especially in the complex aquatic environments.

Nematode-based biomarkers as critical risk indicators on assessing the impact of silver nanoparticles on soil ecosystems

Soil contamination caused by silver nanoparticles (AgNPs) released from sewage treatment plants (STPs) is of great public concern. Understanding the relationships between the physicochemical properties of AgNPs and their toxicity is critical for environmental and health risk analysis. Here we presented an approach for rapidly screening and assessing the potential toxicity risk of AgNPs in general and sludge-treated soils based on the nematode Caenhorhabditis elegans-based probabilistic risk assessment framework. The soil environmental risks were estimated depending on the characteristics of AgNPs and geographic regions. We assessed the risk for soils exceeding a threshold of C. elegans neurotoxicity based on the statistical models. Our results indicated that locomotion inhibition of C. elegans was depending on surface properties, diameter, and exposure time of AgNPs. Here we showed that the overall sewage sludge-released AgNPs-associated soil contamination risk was very low among Europe, U.S., and Switzerland. However, large production and widespread use of AgNPs are highly likely to pose long-term ecotoxicity risk on general and sludge-treated soils, particularly for 26nm citrate-coated AgNPs. Our approach of integrating probabilistic risk model and C. elegans-based ecological indicator provides an effective tool to rapidly screen and assess the impacts of STPs-released AgNPs on soil environment. We suggest that C. elegans as a proxy for estimating soil risk metrics can help develop methods of management for mitigating the metal NPs-induced toxicity on terrestrial ecosystems.

Anti-acne, anti-dandruff and anti-breast cancer efficacy of green synthesised silver nanoparticles using Coriandrum sativum leaf extract

In this present investigation, AgNPs were green synthesised using Coriandrum sativum leaf extract. The physicochemical properties of AgNPs were characterised using UV–visible spectrophotometer, field emission scanning microscopy/energy dispersive X-ray (FESEM/EDX), Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. Further, in vitro anti-acne, anti-dandruff and anti-breast cancer efficacy of green synthesised AgNPs were assessed against Propionibacterium acnes MTCC 1951, Malassezia furfur MTCC 1374 and human breast adenocarcinoma (MCF-7) cell line, respectively. The flavonoids present in the plant extract were responsible for the AgNPs synthesis. The green synthesised nanoparticles size was found to be ≈37nm. The BET analysis result shows that the surface area of the synthesised AgNPs was found to be 33.72m2g−1. The minimal inhibitory concentration (MIC) of AgNPs for acne causative agent P. acnes and dandruff causative agent M. furfur was found to be at 3.1 and 25μgmL−1, respectively. The half maximal inhibitory concentration (IC50) value of the AgNPs for MCF-7 cells was calculated as 30.5μgmL−1 and complete inhibition was observed at a concentration of 100μgmL−1. Finally, our results proved that green synthesised AgNPs using C. sativum have great potential in biomedical applications such as anti-acne, anti-dandruff and anti-breast cancer treatment.

Silver nanoparticles: in vivo toxicity in zebrafish embryos and a comparison to silver nitrate

The wide antimicrobial administration of silver nanoparticles (AgNPs) has raised the risks associated with their exposure. However, there is lack of robust toxicological data for the applied AgNPs to be in line with their wide antimicrobial applications. This study therefore set out to assess the in vivo toxicity of two different sizes of AgNPs using zebrafish embryos (Danio rerio) as a brilliant in vivo model. The pivotal role of size of AgNPs in the toxicity was highlighted, wherein the smaller AgNPs (Ag-9 nm) exhibited more embryo toxicities than the larger particles (Ag-30 nm). Much uncertainty still exists about whether the cause of in vivo toxicity of AgNPs is the physicochemical properties of AgNPs or the released silver ions (Ag+). Therefore, another purpose of this study is to compare the toxicity of AgNPs with silver nitrate (AgNO3) in terms of mortality, hatchability and cardiac rates, and a series of phenotypic endpoints of zebrafish embryos. Collectively, the present results point towards the remarkable size-dependent toxicity of AgNPs. Wherein, the smaller AgNPs (9 ± 2 nm) induce increased mortality rates and decreased hatchability rates than the larger particles (30 ± 5 nm) in a dose-dependent manner. Besides, AgNPs and AgNO3 induce holistic different toxic mortality and hatchability rates. We have also found striking discrepancies in the phenotypic defects that were induced by AgNPs and AgNO3. The significant phenotypic defect induced by AgNPs is the axial deformity, while it is the deposition of Ag+ on the embryonic chorion for AgNO3. Therefore, it is proposed that AgNPs and AgNO3 induce different in vivo toxicities.

Interactions between suspension characteristics and physicochemical properties of silver and copper oxide nanoparticles: A case study for optimizing nanoparticle stock suspensions using a central composite design

The preparation of a stable nanoparticle stock suspension is the first step in nanotoxicological studies, but how different preparation methods influence the physicochemical properties of nanoparticles in a solution, even in Milli-Q water, is often under-appreciated. In this study, a systematic approach using a central composite design (CCD) was employed to investigate the effects of sonication time and suspension concentration on the physicochemical properties (i.e. hydrodynamic diameter, zeta potential and ion dissolution) of silver (Ag) and copper oxide (CuO) nanoparticles (NPs) and to identify optimal conditions for suspension preparation in Milli-Q water; defined as giving the smallest particle sizes, highest suspension stability and lowest ion dissolution. Indeed, all the physicochemical properties of AgNPs and CuONPs varied dramatically depending on how the stock suspensions were prepared and differed profoundly between nanoparticle types, indicating the importance of suspension preparation. Moreover, the physicochemical properties of AgNPs and CuONPs, at least in simple media (Milli-Q water), behaved in predictable ways as a function of sonication time and suspension concentration, confirming the validity of our models. Overall, the approach allows systematic assessment of the influence of various factors on key properties of nanoparticle suspensions, which will facilitate optimization of the preparation of nanoparticle stock suspensions and improve the reproducibility of nanotoxicological results. We recommend that further attention be given to details of stock suspension preparation before conducting nanotoxicological studies as these can have an important influence on the behavior and subsequent toxicity of nanoparticles.

Silver nanoparticle‐induced oxidative stress, genotoxicity and apoptosis in cultured cells and animal tissues

Silver nanoparticles (AgNPs) have emerged as an important class of nanomaterials for a wide range of industrial and medical applications. However, the unique properties of AgNPs could potentially lead to unexpected hazards to both human health and the well being of the environment. Possible mechanisms of AgNP-induced toxicity include the stimulation of oxidative stress, genotoxicity and apoptosis. In this study, a number of previous studies are therefore summarized that demonstrate oxidative stress-, genotoxicity- and apoptosis-related changes brought about by AgNPs in cultured cells and animal tissues. The physicochemical properties of AgNPs that are involved in encouraging such changes are also discussed.