Average Particle Size Of AgNPs Research Articles

Green fabricated silver nanoparticles as a new eco-friendly insecticide for controlling stored cowpea bug Callosobruchus maculatus (Coleoptera: Bruchidae)

The stored cowpea bug Callosobruchus maculates F. (Coleoptera: Bruchidae) is a significant pest. The present study involves the synthesis of silver nanoparticles (AgNPs) with the assistance of Cissus quadrangularis stem and their efficacy in controlling C. maculatus, a species of beetle belonging to the family Bruchidae. The confirmation of nanoparticle formation was achieved via UV–visible spectroscopy, while the physical and chemical properties were analysed through the use of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Zetasizer measurement of the average particle size of AgNPs synthesized using C. quadrangularis stem extract. The morphology of the nanoparticles was predominantly spherical and elliptical, and their range size was determined from 9.23 nm to 19.23 nm through analysis of the TEM images. Aggregates and clusters of particles are generated. The efficacy of C. quadrangularis stem water extract, silver nitrate (AgNO3), and synthesized AgNPs as insecticides against C. maculates was evaluated. The evaluation of the pesticidal effect was conducted through the implementation of antifeedant and filter paper-impregnated methodologies. The study revealed that the efficacy of C. quadrangularis silver nanoparticles (Cq-AgNPs) surpassed that of C. quadrangularis aqueous extract. The aqueous extract exhibited an LC50 value of 5.22 mg/L, while the synthesized Cq-AgNPs demonstrated an LC50 value of 1.87 mg/L. The antifeedant method was utilized to determine the LC50 readings of the aqueous extract, and synthesized Cq-AgNPs, which were found to be 4.01 mg/L, and 1.51 mg/L, respectively. These results suggest that Ag nanoparticles synthesized by C. quadrangularis may be useful in protecting stored grain pests against C. maculates.

Biosynthesis and Characterization of Silver Nanoparticles Coated with Metabolites Extracted from Clerodendron phlomoides with Its Biochemical Studies in Liver Tissue

Silver nanoparticles (AgNPs) have been used as a potential nanomaterial-based drug delivery vehicle for liver cancer treatment, as it induces cell death and produces cytotoxicity against cancerous cells at a low concentration. The biosynthesis of green metallic nanoparticles uses secondary metabolites in plant extracts instead of toxic chemicals for a reduction-oxidation (redox) reaction. The biosynthesis of AgNPs with the aqueous extract of Clerodendron phlomoides was performed in this study. The phytochemical analysis of C. phlomoides extract using gas chromatography-mass spectrometry (GC-MS) confirmed the presence of redox metabolites. The peak at 489 nm in UV-visible spectra confirmed the formation of bioactive AgNPs reduced from silver nitrate solution, whereas the Fourier-transform infrared (FTIR) spectra indicated the bioactive molecules of plant extracts that are responsible for the formation. Scanning electron microscope (SEM) micrograph revealed the formation of spherical and ovoid structures of AgNPs, whereas transmission electron microscope (TEM) micrograph confirmed the size of AgNPs, which varies from 25 nm to 100 nm. X-ray diffraction (XRD) spectra showed the crystalline nature of AgNPs, and the size of crystallite was 4 nm, while dynamic light scattering (DLS) analysis confirmed the average particle size of AgNPs to be around 125 nm. In vivo studies showed that bioactive AgNPs have a significant anticancer potential against liver cancer, whereas biochemical studies of rats’ liver tissue samples confirmed that bioactive AgNPs produced a potential hepatoprotective effect against diethylnitrosamine-induced liver cancer.

Green biosynthesis, characterization of silver nanoparticles using a green alga Spirogyra sp., and their antioxidant and enzyme activities

A simple, environmentally friendly, inexpensive, and one-step alternative method was reported for the green biosynthesis of silver nanoparticles (AgNPs) operating the Spirogyra sp. extract as a reducing and stabilizing substance. Concentration of AgNO3 and reaction time were optimized to prepare AgNPs under controlled conditions. The synthesized silver nanoparticles were characterized by UV-Vis absorption spectroscopy, fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and elemental mapping. The TEM analysis showed that the average particle size of AgNPs was 18.3 nm. Structural details of silver nanoparticles elucidated by Selected Area Electron Diffraction (SAED) based on TEM images. In addition, biological activity tests were applied to nanoparticles and algal extracts to determine antioxidant activity (3 different tests: DPPH (1,1-diphenyl-2-picrylhydrazil) radical scavenging activity, total phenolic content (TPC) and total flavonoid content (TFC)) and α-glucosidase enzyme inhibition. Antioxidant activity and α-glucosidase enzyme inhibition values of silver nanoparticles are higher than the values of Spirogyra sp. extracts.

Green synthesis and characterization of silver nanoparticles through the Piper cubeba ethanolic extract and their enzyme inhibitory activities.

Introduction: The area of "Green Synthesis of Nano-medicine," as compared to its synthetic counterparts, is a relatively safer research technology for various biomedical applications, including identification, therapeutic application, and prevention of pathological conditions, pain control, safety, and development of human wellness. The present study explored the synthesis and characterization of AgNPs using the ethanolic extract of Piper cubeba fruit as a reducing and stabilizing agent and its potential as an enzyme inhibitory agent. Urease inhibitors are helpful against many severe diseases, including gastric ulcers induced by Helicobacter pylori. Method: The fruits of the Piper cubeba plant were taken and ground to a fine powder. Plant material was added to 500 ml ethanol, and the mixture was filtered. The solvent of the filtrate was evaporated, and a thick, gummy extract was obtained and stored at 4°C in the refrigerator. AgNPs were green synthesized from solutions of AgNO3 using the P. cubeba extract, which was indicated by a change in the color from light brown to deep brown. The synthesized AgNPs were characterized via Ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Results and Discussion: Analysis showed the reduction of Ag+ to Ag0 at room temperature (25°C), and the average particle size of AgNPs was in the range of 40-80 nm. Consequently, the synthesized AgNPs were evaluated for their anti-urease activity. The maximum urease inhibition of the Piper cubeba ethanolic extract was 88.5% at 5 mg conc., and of derived nanoparticles was 78.6% at 0.05 mg conc. The results were nearly similar to the control drug, i.e., thiourea (0.5 and 0.6 mM conc., respectively). Conclusion: The study concluded that the P. cubeba extract, as well as its green-derived AgNPs, might prove to be a better and safer substitute for their enzyme inhibitory potential in emerging medicine and novel drug delivery techniques to improve and maintain human health.

Controllable synthesis of silver nanoparticles using a multi-stage microfluidic reactor driven by two valveless piezoelectric pumps

Combining microfluidics and piezoelectric drive technology, a controllable synthesis method of silver nanoparticles (AgNPs) is proposed, which uses a multi-stage microfluidic reactor driven by two valveless piezoelectric pumps. First, the liquid-phase synthesis mechanism of AgNPs and the working principle of the reactor were analyzed. Then, in order to investigate the influence of working parameters, reductant concentration, and polyvinylpyrrolidone (PVP) addition or not on the synthesis of AgNPs, a series of related experiments were carried out. The synthesized AgNPs were characterized by UV-spectrometer and transmission electron microscope (TEM). Experimental results show that the operating parameters of the reactor have an effect on the particle size, concentration, and homogeneity of the synthesized AgNPs. Among them, the mixing reaction performance of this reactor is gradually enhanced during the driving voltage increase from 30 Vpp to 120 Vpp. During this period, the average particle size of AgNPs in colloids increase from 24.67 nm to 25.93 nm and the concentration increase from 0.541 to 1.602. while the particle size deviation decreases from 7.03 nm to 4.15 nm, that is, the homogeneity gradually became better. As the concentration ratio of reductant to precursor increases from 0.5:1–4:1, the average particle size of AgNPs synthesized in the colloid gradually increases from 21.35 nm to 28.19 nm. However, the concentration of AgNPs in the colloid increases and then decreases, and the homogeneity becomes better and then worse. Especially, when the concentration ratio of reductant to precursor is 2:1, the synthesized AgNPs have higher concentration and smaller particle size deviation. Adding a reasonable amount of protectant (mPVP/mAg=1.5) can effectively inhibit the agglomeration of the synthesized AgNPs, and can ensure the preparation of AgNPs with good homogeneity and monodispersity. The related research shows that the proposed multi-state microfluidic reactor driven by two valveless piezoelectric pumps has good mixing reaction performance, and can be applied to the controllable synthesis of high-quality AgNPs under suitable conditions.

Effect of loading rate of nano-silver on degradation of methyl orange by AgNPs@SBPN composite catalyst

To determine the influence of loading rate of nano-silver on the degradation of pollutants, AgNPs were immobilized on the surface of small black phosphorus nanosheet (SBPN) with different loadings (2.5 wt%, 5 wt%, 7.5 wt% and 10 wt%) and constructed a series of composite photocatalysts, namely AgNPs@SBPN. The structure, size and morphological properties of AgNPs@SBPN were investigated. The photocatalytic performance of bare BP and AgNPs@SBPN was compared. The results confirmed that the surface plasmon resonance effect of loaded AgNPs increased the absorption of visible light and separation efficiency of charges of AgNPs@SBPN. The photocatalytic degradation performance of AgNPs@SBPN was AgNPs loading rate dependent. Compared with the pure BP, degradation rate of methyl orange (MO) increased by 35.3%–187.7% as the loading increased from 2.5 wt% to 7.5 wt%. The findings indicated that too much (>10 wt%) or little nano silver (<2.5 wt%) was not conducive to the rapid transfer of electrons, resulting in low degradation efficiency. Under the optimal condition of AgNPs loading rate (7.5 wt%), the average particle size of AgNPs was 34 nm. About 72.0% MO was degraded within 120 min by 7.5 wt%-AgNPs@SBPN with the photocurrent density of 15.3 μA cm−2. Through liquid chromatography-mass spectrometry analysis, MO may be mineralized into CO2, H2O and NO3− under the oxidation of ·OH and ·O2−.

Investigation on strength enhancement of cement paste using biogenic nanoparticles

The present study attempts to understand the effect of hydrophobic water-dispersed biogenic silver nanoparticles (AgNPs) over commercial silica nanoparticles (SiNPs) on the fresh and hardened properties of cement paste. The average particle size of AgNPs is 10 nm, whereas that of reference SiNPs is 12 nm. The effect of AgNPs replacing 0.5 and 1% of binder material has been studied and compared with the effect of SiNPs. It is observed that the addition of AgNPs does not enhance water requirement for consistency; neither does it adversely impact the setting time. The results on compressive strength of cement paste show higher initial and long term strength for specimens blended with AgNPs with the percentage increment for 3–28 days strength ranging between 40 and 43%, whereas the same for SiNPs ranges from 26 to 29%. For optimized binary mixes with Alccofine, the strength increment from 3 to 28 days ranges from 8 to 30% for AgNPs, whereas for SiNPs it ranges from 10 to 43%. In case of binary mix with Fly Ash C, addition of AgNPs improves strength in the range from 31 to 40%, whereas SiNPs improves strength from 10 to 41%. The strength observed with AgNPs is comparable with those of commercial SiNPs with an additional advantage of reduced water demand for consistency, thus making it an attractive alternative for possible applications in mortar and concrete.

Biosynthesis and Characterization of Silver Nanoparticles from Bitter Melon (Momordica charantia) Fruit and Seed Extract and their Antimicrobial Activity

Momordica charantia is a phenolic rich vegetable. In this study, the fruits and seeds extract of M. charantia were used to synthesize silver nanoparticles (Ag NPs) using biotechnological approach. Structural, morphological, and antimicrobial properties of the synthesized Ag-NPs were characterized using UV/Vis Spectrophotometry, Dynamic Light Scattering (DLS), High Resolution Transmission Electronics Microscopy (HRTEM), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray diffraction (XRD). In DLS, the average particle size of Ag-NPs was found 17.5 ± 2.1 nm and 18.3 ± 1.9 nm using seed and fruit extract, respectively. HRTEM has revealed their spherical structure for both seed and fruit extract of M. charantia. FESEM images found Ag-NPs with the size between ~20 and ~35 nm. The Ag NPs exhibited Surface Plasmon Resonance (SPR) centered at 405 nm for seed extract and 402 nm for fruit extract using a UV–visible spectrophotometer. FT-IR results showed phenolic and carbohydrate compounds involved in the synthesis of the Ag NPs. Furthermore, the synthesized Ag NPs has found highly rich in antibacterial properties against Escherichia coli and Pseudomonas aeruginosa bacterium. Thus, bioconversion of Ag NPs by M. charantia could be employed as a potential antibacterial source to eliminate pathogenic microorganisms from agricultural and food preservation industry.

Green Synthesis of AgNPs() Ultilizing Delonix Regia Extract as Anticancer and Antimicrobial Agents**

AbstractSilver is an effective antimicrobial agent with low toxicity, which is important especially in the treatment of burn wounds where transient bacteremia is prevalent. In this research, the green method was employed to synthesis silver nanoparticles (AgNPs). The synthesized AgNPs were characterized using IR, XRD, DLS and UV/Visible Spectrophotometery. XRD pattern of AgNPs has a face‐centered cubic (FCC) form and crystalline lattice with a crystallite size of 12 nm. FT‐IR spectra indicate the functional groups of phytochemical compounds at Delonix regia extract DRE and AgNPs. DLS showed the distribution of average particle size of AgNPs that have 11 nm mean size of the particle. The prepared AgNPs were screened for their cytotoxic effect against colon carcinoma cells (HCT‐ 116 cell line), hepatic cellular carcinoma cells (HepG‐2) and breast carcinoma cells (MCF‐7). The cytotoxic effect of AgNPs is close to the cytotoxic effect of Doxorubicin standard drug. The toxicity of the AgNPs was tested on bacterial species such as Gm (+) positive bacteria (Bacillus subtilis) and Gm (‐) negative bacteria (Serrati amarcescence and Escherichia coli) and fungal species such as Candida albicans, Getrichm candidum and Aspergillus flavus. The antimicrobial activity of AgNPs was greater towards Gm (+) positive bacteria compared to Gm (‐) negative bacteria. These biological activities of the synthesized AgNPs could be promised to use it as a drug.

Size optimisation of silver nanoparticles synthesised by gallic acid using the response surface methodology

This work reports the synthesis of silver nanoparticles (AgNPs) from Ag nitrate (AgNO3) using the gallic acid (GA) as a green methodology without utilisation of hazardous chemicals. The effects of variables such as AgNO3 concentration, GA concentration, and pH on the average particle size of AgPs were optimised through response surface methodology based on the central composite design at three levels to obtain the desired response, i.e. minimum average particle size. The formation of AgNPs at each experiment was characterised by ultraviolet–visible (UV–vis) spectroscopy and the average particle size was measured by dynamic light scattering (DLS). To evaluate the significance of factors on the response and their quantitative effects, analysis of variance was carried out. The results indicated that the pH was the most effective factor on the response. The AgNPs synthesised at optimised conditions (5.42 mM of AgNO3, 6.25 mM of GA, and pH = 9.02) were characterised by X-ray diffraction, DLS, field-emission scanning electron microscope, energy dispersive X-ray, transmission electron microscopy, UV–vis spectroscopy, and Fourier-transform infrared spectroscopy. On the basis of the DLS, the average particle size of AgNPs obtained 8 nm, which was in satisfactory agreement with the predicted value (7.51 nm) by model.

Assessment of silver nanoparticles decorated starch and commercial zinc nanoparticles with respect to their genotoxicity on onion

High throughput production of silver nanoparticles (AgNPs) having controlled size appropriate for industrial purposes were achieved via using facile and ecofriendly chemical reduction method. Native rice starch was used as reductant for silver ions (Ag+) to silver atoms (Ag0), as well as stabilizing for the obtainable AgNPs. Two different concentrations; 2000 ppm and 4000 ppm were successfully prepared and coded as AgNPs-2000 and AgNPs-4000 respectively. The attained AgNPs were characterized via ultra-visible (UV–vis) spectra, Transmission Electron Microscope (TEM), Energy dispersive X-ray (EDX), Particle size analyzer, polydispersity index (PDI) and zeta potential (ζ-potential). The average particle size of AgNPs (2000 ppm) was 8 nm with PDI = 0.01 which affirm the monodispersity and homogeneity of the produced AgNPs. Meanwhile, the size majority for the as prepared AgNPs (4000 ppm) was 24 nm with PDI = 0.021. Based on the aforementioned data, AgNPs prepared with a high concentration (4000 ppm) compared with the commercialized ZnNPs were used for the genotoxicity study on onion. Root-tips was used for cytogenetic studies using onion (Allium cepa L.) which are excellent materials for cytological and genotoxicity studies. Genotoxicity results explored that, by using AgNPs ≥40 ppm, the abnormalities disturbed chromosomes were observed and detected, that reflects the genotoxicity effect of these nanoparticles at this dose. In addition, the commercial available ZnNPs with the recommended dose (2 g/L) displayed also severe genotoxicity on A. cepa L. root meristem cells.

Comparative study of antifungal activity of silver and gold nanoparticles synthesized by facile chemical approach

Colloidal solutions of silver nanoparticles (Ag-NPs) and gold nanoparticles (Au-NPs) have been proved to be suitable antimicrobial agents. In this study, Ag-NPs (yellow color) and Au-NPs (wine red color) have been produced by chemical reduction method using silver nitrate and chloroauric acid as metal precursors with sodium borohydride as reducing agent for Ag-NPs and tannic acid as reducing agent for Au-NPs and trisodium citrate as a stabilizing agent in both cases. UV–vis spectroscopy graph shows the adsorption for Ag-NPs and Au-NPs to be 440 nm and 520 nm respectively. X-ray diffraction (XRD) analysis showed the highly crystalline nature of Ag-NPs and Au-NPs with (111), (200), (220), (311) orientations. TEM and SEM reveal the uniform spherical morphology of Ag-NPs and Au-NPs with the presence of elemental Ag and Au metal analysed by EDAX. SAD confirms the orientation of Ag-NPs and Au-NPs with XRD analysis. The average particle size of Ag-NPs and Au-NPs was found to be 25 nm and 34 nm respectively investigated by DLS. The antifungal activity of Ag-NPs and Au-NPs on fungal cells, i.e., Candida Albicans and S.Cerevesiae showed diminished fungal growth by developing inhibition zones. The comparative studies demonstrate that Ag-NPs are more active than Au-NPs in diminishing fungus.

Antioxidant and anticancer activities of green synthesized silver nanoparticles using aqueous extract of tubers of Pueraria tuberosa

In the present study, we have synthesized silver nanoparticles (AgNPs) using Pueraria tuberosa aqueous extract (PTAE) in a straightforward manner without involvement of toxic chemicals. Various reaction parameters (reaction time, AgNO3 concentration, pH, reaction temperature and PTAE concentration) were optimizeded for the synthesis of AgNPs through visual observation of colour change and absorption peak by UV–Vis spectroscopy. The green synthesized AgNPs were analyzed by DLS, FTIR, SEM, TEM, EDS and XRD for their bio-physical characteristics. The AgNPs were screened for their antioxidant activity by determining total antioxidant capacity (TAC) and anticancer potential by MTT assay. The average particle size of AgNPs was 162.72 ± 5.02 nm with zeta potential of –30.14 ± 2.08 mV. The spherical shape of the AgNPs was confirmed by SEM and TEM. FTIR spectra showed the involvement of different phytoconstituents as capping and stabilizing agents in the synthesis of AgNPs. The TAC of the optimized synthesized AgNPs was more than PTAE. The IC50 of synthesized AgNPs against MCF-7, MDA-MB-231, SKOV-3, U-87 and NCI/ADR cell lines was 3.859, 1.128, 29.36, 6.053 and 25.49 µg/ml, respectively. The green synthesized AgNPs has potential for use in the treatment of different types of cancer.

Optimisation of significant parameters through response surface methodology in the synthesis of silver nanoparticles by chemical reduction method

Response surface methodology coupled with the central composite design (CCD) was employed to optimise the significant parameters in the synthesis of silver nanoparticles (AgNPs) by chemical reduction method to obtain smaller average particle size. Different parameters such as the ethylene glycol (EG) concentration as reducing agent, the polyvinyl pyrrolidone (PVP) content as stabiliser and the pH were selected as they have the dominant effects on the particle size of AgNPs. Each of these parameters was studied at three levels. The average particle size of AgNPs was considered as the response value and determined by dynamic light scattering (DLS) analysis. The statistical analysis showed that the pH emerged as the most significant parameter influencing the average particle size and after that, the PVP content was also a significant parameter. The AgNPs synthesised under optimal conditions (6.88 M of EG, 0.5% of PVP and pH = 11) were characterised by UV–vis spectroscopy, X-ray diffraction (XRD), DLS, zeta potential, field emission scanning electron microscope and energy dispersive X-ray analysis. The XRD pattern showed the face-centred cubic silver and the average crystallite size of AgNPs was 30 nm. The average particle size of AgNPs was 37.35 nm according to DLS analysis, which was in good agreement with the predicted value (37.65 nm) by CCD.

Fabrication, optimization, and characterization of noble silver nanoparticles from sugarcane leaf (Saccharum officinarum) extract for antifungal application

Metal nanoparticles obtained from green route are gaining significant prominence as a result of their potential applications in nanomedicine and material engineering. Overall metal nanoparticles studied, silver nanoparticles (AgNPs) clutch prominent place in nanoparticles research field. Herein, we have reported the green synthesis of Saccharum officinarum leaf biomass extract-mediated synthesis of AgNPs. Initial nanoparticle production was confirmed by visual observation as color change from light yellow to bright brown color with yellow shade and spectrophotometrically at 450 nm and the various reaction conditions were optimized. The FTIR spectra of the biomass extract and synthesized AgNPs authorized the presence of phyto constituents as capping agent. The High Resolution-Transmission Electron Microscopy (HR-TEM) analyses confirm the morphology and the average particle size of AgNPs as ~28.2 nm. The crystalline nature oxide state and mean particle diameter of AgNPs were confirmed by X-ray diffraction (XRD) analysis, Selected Area Electron Diffraction (SAED) pattern and face-centered cubic (FCC). The obtained AgNPs show moderate to good antifungal activity against Phytophthora capsici, Colletotrichum acutatum and Cladosporium fulvum as 10, 12 and 14 mm zones of inhibition against synthesized AgNPs at 250 μg/well, respectively.

Study on the synthesis of antibacterial plastic by using silver nanoparticles doped in zeolite framework

Silver nanoparticles (AgNPs) doped in the zeolite framework (AgNPs/Z) were successfully synthesized by γ-irradiation in ethanol solution of silver ion-zeolite (Ag+/Z) prepared by ion exchange reaction between silver nitrate (AgNO3) and zeolite 4A. The effects of the Ag+ concentration and irradiation dose on the formation of AgNPs/Z were also investigated. AgNPs/Z with the silver content of about 10,000 ppm and the average particle size of AgNPs of about 27 nm was characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM). Firstly, AgNPs/Z was added into PP resins for creation of PP-AgNPs/Z masterbatch (Ag content of ~10.000 ppm) and then PP-AgNPs/Z plastics were preapared by mixing masterbatch with PP resins. The antibacterial activity of the PP-AgNPs/Z plastics was investigated against Gram-negative bacteria Escherichia coli (E. coli). The results showed that PP-AgNPs/Z plastic contained 100 ppm of Ag possessed a high antibacterial property, namely the bactericidal effect was more than 96 % on the platic surface. In conclusion, possessing many advantages such as: vigorously antibacterial effect and good dispersion in plastic matrix, AgNPs/Z is promising to be applied as bactericidal agent for plastic industry.

Biofabricated silver nanoparticles as green catalyst in the degradation of different textile dyes

Biogenic silver nanoparticles (AgNPs) synthesized by Sterculia acuminata fruit extract was characterized by UV–vis spectroscopy, XRD, TEM, FTIR, PSA, and Zeta potential studies. Formation of AgNPs is initially confirmed by UV–vis spectroscopic studies with the characteristic band at 426nm. TEM and XRD reports revealed that AgNPs are highly crystalline and spherical in shape with average particle size of ∼10nm. PSA studies revealed that average particle size of AgNPs is 10.3nm which is in close agreement with TEM reports. FTIR studies indicated the presence of different functional groups on the surface of the AgNPs indicating the stability of AgNPs by capping of biomolecules onto the surface which is further supported by zeta potential studies with the negative zeta potential value of −39.2mV. Further catalytic efficiency synthesized AgNPs was evaluated for the reduction/degradation of various organic dyes such as 4-nitrophenol (4-NP), methylene blue (MB), methyl orange (MO), phenol red (PR) and direct blue 24 (DB24). It was found that degradation of MB and DB24 was faster than that of other dyes. This is the first report on degradation of organic dyes PR and DB24 using NaBH4 as reducing agent in the presence of catalytic amount of AgNPs.

A novel method for the quantification, characterisation and speciation of silver nanoparticles in earthworms exposed in soil

Environmental context Increasing production and application of engineered nanoparticles has led to an increased potential for their environmental release, raising ecotoxicological concerns. To appropriately characterise the fate, effects and risks of engineered nanoparticles in environmental systems, methods are essential to characterise nanoparticles in complex biological matrices. This study reports a method that extracts nanoparticles from tissues of organisms, enabling their detection, quantification and characterisation. Abstract Currently, metal engineered nanoparticles (ENPs) in tissues are generally quantified based on total concentrations after acid digestion of samples. Electron microscopy has also been used for non-quantitative characterisation of NPs in situ, and can be enhanced with tissue-processing methods that can extract NPs with minimal destruction. For a proper risk assessment, it is essential to quantify and characterise the ENPs in both exposure media and organisms. For this, we developed a method using a combination of enzymatic tissue processing, followed by single particle inductively coupled plasma–mass spectrometry (sp-ICP-MS) to characterise and quantify AgNPs in tissues of earthworms after in vivo exposure in soil to 50-nm AgNPs or AgNO3. Tissue concentration of Ag in worms exposed to 250mg AgNP kg–1 soil (dry weight) was 0.502±0.219mgkg–1 (dry weight) reflecting a bioaccumulation factor of 0.002. In both AgNP- and AgNO3-treated groups, the metal-rich granule fraction contained the highest Ag concentrations (77 and 64% respectively). Total Ag contained in the earthworm tissue of the AgNP- and AgNO3-treated groups comprised ~34 and &lt;5% particulate Ag respectively. Average particle size of AgNPs extracted from tissues was consistent with exposure material (44 v. 43nm respectively). High resolution field-emission gun scanning electron microscopy in combination with energy-dispersive X-ray (FEG-SEM/EDX) identified individual AgNPs in tissue extracts with corresponding spectral elemental peaks, providing further evidence of tissue particle uptake and composition.

Biosynthesis of Silver Nanoparticles by Marine Invertebrate (Polychaete) and Assessment of Its Efficacy against Human Pathogens

Synthesis of metallic nanoparticles by chemical and physical method makes the process often cumbersome due the usage of toxic and expensive chemicals. The present study reports the biosynthesis of silver nanoparticles using marine invertebrate (polychaete) extract at room temperature. The ultraviolet-visible (UV-Vis) spectroscopy revealed the formation of silver nanoparticles (AgNPs) by exhibiting the typical surface plasmon absorption maximum at 418–420 nm. Structure and composition of AgNPs were analyzed by atomic force microscopy (AFM). Average particle size of AgNPs ranged from 40 to 90 nm, confirmed by scanning electron microscopy (SEM) analysis. The energy-dispersive X-ray spectroscopy (EDX) of the nanoparticles dispersion confirmed the presence of elemental silver signal, whereas X-ray diffraction (XRD) substantiated the crystalline nature of synthesized nanoparticle. Fourier transform infrared spectroscopy (FTIR) spectral analysis showed the presence of amides phenols, ethers, and fatty acids as major biomolecules responsible for the reduction of silver ions. The possible mechanism responsible for the synthesis of AgNPs by these biomolecules was also illustrated by chemical reactions. The synthesized AgNPs showed comparatively good antibacterial activity against the tested human pathogens. This study advocates that not only plants and microbes but also marine invertebrates do have potential for synthesizing nanoparticles by a cost-effective and eco-friendly approach.

Evaluation of the Disinfectant Performance of Silver Nanoparticles in Different Water Chemistry Conditions

This study aimed to determine the effect of different water chemistry conditions on the bactericidal properties of silver nanoparticles (AgNPs). Reduced disinfection performance of AgNPs was obtained in divalent cationic solutions in comparison with monovalent solutions with the same concentration. Average particle size of AgNPs increased with increasing electrolyte concentration as divalent cations (Ca2+ and Mg2+) produced larger AgNPs aggregates than those formed with monovalent solutions. ξ-potential measurements showed that AgNPs in divalent cationic solutions had low absolute ξ-potential values (-9.8 to -23.2 mV), whereas the values obtained in monovalent solutions were considerably more. The measurements of the concentration of ionic silver released indicated that the fraction of dissolved Ag+ (5.9–18.8 μg/L) was around 0.1% of the total mass of Ag0 added. The contribution of Ag+ to the overall disinfection performance was negligible at the conditions tested. In this study, different physicochemical properties of silver nanoparticles and the survival rate of Escherichia coli (E. coli) in different AgNPs solutions were analyzed. The data collected lead to a correlation between survival rate of E. coli and average size of AgNPs. The results show a strong correlation between these two parameters that can be fitted to a saturation type curve, reaching a survival plateau around 20% survival at an average particle size of 200 nm for all the water chemistry conditions tested.