scholarly journals A novel explanation for the enhanced colloidal stability of silver nanoparticles in the presence of an oppositely charged surfactant

2017 ◽  
Vol 19 (41) ◽  
pp. 28037-28043 ◽  
Author(s):  
Sara Skoglund ◽  
Eva Blomberg ◽  
Inger Odnevall Wallinder ◽  
Isabelle Grillo ◽  
Jan Skov Pedersen ◽  
...  

The structural behavior in aqueous mixtures of negatively charged silver nanoparticles (Ag NPs) together with the cationic surfactants cetyltrimethylammonium bromide (CTAB) and dodecyltrimethylammonium chloride (DTAC), respectively, has been investigated using SANS and SAXS.

2021 ◽  
Author(s):  
Mert Saraçoğlu ◽  
Begüm Bacınoğlu ◽  
Sıddıka Mertdinç ◽  
Servet Timur

Abstract In this study, sericin extracted from Bombyx mori silk cocoons was integrated into the well-known Tollens’ method for synthesizing Ag-NPs. Sericin successfully acted as a stabilizer while silver amine complex [Ag(NH3)2]+ was reduced by maltose. As a result, silver nanoparticles with high stability are formed. Possible functional groups related to the stabilization of NPs were investigated by Fourier-transforms infrared spectroscopy (FT-IR). Ag-Ser NPs were characterized by using particle size measurements based on dynamic light scattering (DLS) and transmission electron microscopy (TEM). According to the characterization investigations, Ag-Ser NPs have characteristic (111) face-centered cubic (FFC) plane and were spherical in shape with a narrow size distribution of 20.23 ±6.25 nm. Overall, the sericin-modified Tollens’ method for synthesizing Ag-NPs offers a simple and non-toxic production method to form nanoparticles. Colloidal stability of nanoparticles displays an essential role since their enhanced nano-properties can be diminished by an increase in size due to aggregation and agglomeration. Therefore, the effect of pH on particle stability was investigated through the surface charge of Ag-Ser NPs that was measured using a Zeta-potential analyzer. Results obtained from this study may extend the applicability of silver nanoparticles in biotechnological researches and a potential synthesis route for the application of Ag-Ser NPs as aseptic and therapeutic usages.


2020 ◽  
Vol 17 (5) ◽  
pp. 400 ◽  
Author(s):  
YounJung Jung ◽  
Gabriele E. Schaumann ◽  
Seungyun Baik ◽  
George Metreveli

Environmental contextThe fate of silver nanoparticles (AgNPs) in aqueous systems could be influenced by the hydrophobicity of natural organic matter. We observed that the aggregation and dissolution of oppositely charged AgNPs were controlled by the selectivity and dynamics of sorption processes involving the nanoparticle surface and hydrophobic groups on natural organic matter. These findings will be helpful to understand the fate and effects of coated AgNPs in natural systems. AbstractThe fate of silver nanoparticles (AgNPs) released into aquatic environments is significantly affected by natural organic matter (NOM). However, current studies are still insufficient to understand interactions between NOM and AgNPs because they do not explicitly consider the heterogeneity of NOM. We investigated how NOM components with different properties (hydrophobicity, molecular weight, aromaticity, and polarity of functional groups) interact with AgNPs coated with citrate (Cit) and branched polyethylenimine (BPEI) and influence their colloidal stability and dissolution. Pony Lake fulvic acid (PLFA) selected as a model NOM was fractionated into hydrophobic (HPO) and transphilic (TPI) fractions. Sorption of PLFA molecules with a high content of polar functional groups bound to the aromatic rings onto nanoparticles was more favourable in the case of the TPI fraction, which most likely resulted in higher aggregation for both AgNPs and stronger protection of BPEI-AgNPs against dissolution compared with the HPO fraction. Additionally, in contrast to the Cit-AgNPs, resorption of Ag+ ions released from BPEI-AgNPs and/or sorption of Ag+-PLFA complexes to the nanoparticles was most likely a dynamic process, as suggested by the time-dependent changes in the molecular weight of the PLFA fractions sorbed to the BPEI-AgNP surface. These observations suggest that the accessibility of the AgNP surface for the hydrophobicity-based fractions of NOM as well as their colloidal stability and dissolution are controlled by the type and charge of coating materials and by the molecular weight, aromaticity, and content of polar functional groups of NOM.


NANO ◽  
2016 ◽  
Vol 11 (04) ◽  
pp. 1650046 ◽  
Author(s):  
Manisha Sharma ◽  
Amit Mishra ◽  
Vinod Kumar ◽  
Soumen Basu

Silver nanoparticles (Ag NPs) were synthesized by one-step process in the presence of kollicoat as capping, reducing and stabilizing mediator. The synthesized NPs were characterized by using FTIR, TEM, DLS, XRD, EDS and UV-Vis spectroscopy. The resulting Ag NPs had an incomparable colloidal stability against the salt addition and change of pH. The effect of different synthesis parameters and the catalytic property of the NPs were examined.


Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1007
Author(s):  
Azam Ali ◽  
Mariyam Sattar ◽  
Fiaz Hussain ◽  
Muhammad Humble Khalid Tareen ◽  
Jiri Militky ◽  
...  

The versatile one-pot green synthesis of a highly concentrated and stable colloidal dispersion of silver nanoparticles (Ag NPs) was carried out using the self-assembled tannic acid without using any other hazardous chemicals. Tannic acid (Plant-based polyphenol) was used as a reducing and stabilizing agent for silver nitrate in a mild alkaline condition. The synthesized Ag NPs were characterized for their concentration, capping, size distribution, and shape. The experimental results confirmed the successful synthesis of nearly spherical and highly concentrated (2281 ppm) Ag NPs, capped with poly-tannic acid (Ag NPs-PTA). The average particle size of Ag NPs-PTA was found to be 9.90 ± 1.60 nm. The colloidal dispersion of synthesized nanoparticles was observed to be stable for more than 15 months in the ambient environment (25 °C, 65% relative humidity). The synthesized AgNPs-PTA showed an effective antimicrobial activity against Staphylococcus Aureus (ZOI 3.0 mM) and Escherichia coli (ZOI 3.5 mM). Ag NPs-PTA also exhibited enhanced catalytic properties. It reduces 4-nitrophenol into 4-aminophenol in the presence of NaBH4 with a normalized rate constant (Knor = K/m) of 615.04 mL·s−1·mg−1. For comparison, bare Ag NPs show catalytic activity with a normalized rate constant of 139.78 mL·s−1·mg−1. Furthermore, AgNPs-PTA were stable for more than 15 months under ambient conditions. The ultra-high catalytic and good antimicrobial properties can be attributed to the fine size and good aqueous stability of Ag NPs-PTA. The unique core-shell structure and ease of synthesis render the synthesized nanoparticles superior to others, with potential for large-scale applications, especially in the field of catalysis and medical.


AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Susanna Gevorgyan ◽  
Robin Schubert ◽  
Mkrtich Yeranosyan ◽  
Lilit Gabrielyan ◽  
Armen Trchounian ◽  
...  

AbstractThe application of green synthesis in nanotechnology is growing day by day. It’s a safe and eco-friendly alternative to conventional methods. The current research aimed to study raw royal jelly’s potential in the green synthesis of silver nanoparticles and their antibacterial activity. Royal jelly served as a reducing and oxidizing agent in the green synthesis technology of colloidal silver nanoparticles. The UV–Vis maximum absorption at ~ 430 nm and fluorescence emission peaks at ~ 487 nm confirmed the presence of Ag NPs. Morphology and structural properties of Ag NPs and the effect of ultrasound studies revealed: (i) the formation of polydispersed and spherical particles with different sizes; (ii) size reduction and homogeneity increase by ultrasound treatment. Antibacterial activity of different concentrations of green synthesized Ag NPs has been assessed on Gram-negative S. typhimurium and Gram-positive S. aureus, revealing higher sensitivity on Gram-negative bacteria.


Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4585
Author(s):  
Nicole Jara ◽  
Nataly S. Milán ◽  
Ashiqur Rahman ◽  
Lynda Mouheb ◽  
Daria C. Boffito ◽  
...  

Nanomaterials have supported important technological advances due to their unique properties and their applicability in various fields, such as biomedicine, catalysis, environment, energy, and electronics. This has triggered a tremendous increase in their demand. In turn, materials scientists have sought facile methods to produce nanomaterials of desired features, i.e., morphology, composition, colloidal stability, and surface chemistry, as these determine the targeted application. The advent of photoprocesses has enabled the easy, fast, scalable, and cost- and energy-effective production of metallic nanoparticles of controlled properties without the use of harmful reagents or sophisticated equipment. Herein, we overview the synthesis of gold and silver nanoparticles via photochemical routes. We extensively discuss the effect of varying the experimental parameters, such as the pH, exposure time, and source of irradiation, the use or not of reductants and surfactants, reagents’ nature and concentration, on the outcomes of these noble nanoparticles, namely, their size, shape, and colloidal stability. The hypothetical mechanisms that govern these green processes are discussed whenever available. Finally, we mention their applications and insights for future developments.


Author(s):  
Laure Bobyk ◽  
Adeline Tarantini ◽  
David Beal ◽  
Giulia Veronesi ◽  
Isabelle Kieffer ◽  
...  

Acute exposure of A549 cells to Ag-NPs induces stronger effects on DNA integrity, ROS level, cell metabolism and cell cycle than repeated exposure. Ag-NPs dissolves in both exposure conditions and Ag ions recombine with thiolated proteins.


Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 744
Author(s):  
Petra Peharec Štefanić ◽  
Karla Košpić ◽  
Daniel Mark Lyons ◽  
Lara Jurković ◽  
Biljana Balen ◽  
...  

Silver nanoparticles (AgNPs) are the most exploited nanomaterial in agriculture and food production, and their release into the environment raises concern about their impact on plants. Since AgNPs are prone to biotransformation, various surface coatings are used to enhance their stability, which may modulate AgNP-imposed toxic effects. In this study, the impact of AgNPs stabilized with different coatings (citrate, polyvinylpyrrolidone (PVP), and cetyltrimethylammonium bromide (CTAB)) and AgNO3 on photosynthesis of tobacco plants as well as AgNP stability in exposure medium have been investigated. Obtained results revealed that AgNP-citrate induced the least effects on chlorophyll a fluorescence parameters and pigment content, which could be ascribed to their fast agglomeration in the exposure medium and consequently weak uptake. The impact of AgNP-PVP and AgNP-CTAB was more severe, inducing a deterioration of photosynthetic activity along with reduced pigment content and alterations in chloroplast ultrastructure, which could be correlated to their higher stability, elevated Ag accumulation, and surface charge. In conclusion, intrinsic properties of AgNP coatings affect their stability and bioavailability in the biological medium, thereby indirectly contributing changes in the photosynthetic apparatus. Moreover, AgNP treatments exhibited more severe inhibitory effects compared to AgNO3, which indicates that the impact on photosynthesis is dependent on the form of Ag.


2021 ◽  
Vol 10 (1) ◽  
pp. 412-420
Author(s):  
Mona S. Alwhibi ◽  
Dina A. Soliman ◽  
Manal A. Awad ◽  
Asma B. Alangery ◽  
Horiah Al Dehaish ◽  
...  

Abstract In recent times, research on the synthesis of noble metal nanoparticles (NPs) has developed rapidly and attracted considerable attention. The use of plant extracts is the preferred mode for the biological synthesis of NPs due to the presence of biologically active constituents. Aloe vera is a plant endowed with therapeutic benefits especially in skincare due to its unique curative properties. The present study focused on an environmental friendly and rapid method of phytosynthesis of silver nanoparticles (Ag-NPs) using A. vera gel extract as a reductant. The synthesized Ag-NPs were characterized by transmission electron microscopy (TEM), UV-Vis spectroscopy, Fourier transform infrared (FTIR), and dynamic light scattering (DLS). TEM micrographs showed spherical-shaped synthesized Ag-NPs with a diameter of 50–100 nm. The UV-Vis spectrum displayed a broad absorption peak of surface plasmon resonance (SPR) at 450 nm. The mean size and size distribution of the formed Ag-NPs were investigated using the DLS technique. Antibacterial studies revealed zones of inhibition by Ag-NPs of A. vera (9 and 7 mm) against Pseudomonas aeruginosa and Escherichia coli, respectively. Furthermore, the antifungal activity was screened, based on the diameter of the growth inhibition zone using the synthesized Ag-NPs for different fungal strains. Anticancer activity of the synthesized Ag-NPs against the mouse melanoma F10B16 cell line revealed 100% inhibition with Ag-NPs at a concentration of 100 µg mL−1. The phytosynthesized Ag-NPs demonstrated a marked antimicrobial activity and also exhibited a potent cytotoxic effect against mouse melanoma F10B16 cells. The key findings of this study indicate that synthesized Ag-NPs exhibit profound therapeutic activity and could be potentially ideal alternatives in medicinal applications.


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