Size control over spherical silver nanoparticles by ascorbic acid reduction

Qin, Yaqiong; Ji, Xiaohui; Jing, Jing; Hong, Liang; Wang, Hongli; Yang, Wensheng

doi:10.1016/j.colsurfa.2010.10.013

Cited by 355 publications

(207 citation statements)

References 30 publications

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“…3 The loss of the lattice was accompanied by the appearance of the size-dependent physicochemical properties of Figure 3a and b describes the changes in the fluorescence and UV-vis absorption spectra during the etching process, showing that the fluorescence intensity at 428 nm and absorbance at 349 nm increased synchronously, and an obvious blue shift was observed at the UV-vis absorption peak within 12 h after the addition of GSH, which showed that the nanoparticles in the solution changed from larger nanocrystals to small nanoclusters, and the increasing absorbance showed the increase in the concentration of Ag NCs as the etching process progressed. 35,36 The color of the Ag colloid solution changed from the original dark brown (before adding GSH) to reddish-brown (72 h after the addition of GSH) and then to colorless after 168 h (Figure 3c), and the blue emission of the diluted Ag NCs solutions brightened correspondingly over time (Figure 3d).…”

Section: Resultsmentioning

confidence: 99%

The pH-switchable agglomeration and dispersion behavior of fluorescent Ag nanoclusters and its applications in urea and glucose biosensing

et al. 2016

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Water-soluble fluorescent Ag nanoclusters (Ag NCs) with distinct pH-switchable agglomeration and spectral signal responses are prepared using a facile etching method. Increased and decreased pH cause the Ag NCs to switch between agglomeration and dispersion, accompanied by decreases in and recoveries of fluorescence intensity and absorbance. The pH switchable behavior of the Ag NCs is attributed to carboxyl groups on the nanocluster surface that are rich in the citrate and amido functional groups of ligands (glutathione), creating an easily formed, weak molecular interaction among Ag NCs (for example, hydrogen bonding) and maintaining a balance in the colloidal solution, whereas a change in pH will disrupt the balance, leading to the reversible agglomeration of Ag NCs and the switchable spectral signal response. In addition, because urea and glucose can change the pH of a solution by producing NH 3 and gluconic acid in enzyme-catalyzed reactions, the pH-switchable behavior of the Ag NCs is used to develop them as an optical probe to establish a regenerated biosensing platform for the sensitive and selective detection of urea and glucose, and the test results are satisfactory. INTRODUCTIONMetal nanoparticles on an~2 nm scale are defined as metal nanoclusters, and they show physicochemical properties that are significantly different from those of their bulk form. Fluorescent metal nanoclusters composed of a small number of atoms have attracted research interest because of their unique properties and molecule-like behavior. 1,2 In recent decades, many fluorescent metal nanoclusters, especially nanoclusters of Au and Ag, among noble metals, have been reported, and the ligands that stabilize these small nanoparticles have a key role in their fundamental properties: (i) ligands can influence optical properties by transferring their charge to the metal cores or by directly donating delocalized electrons contained on them to the metal cores; 3,4 (ii) surface ligands can determine the physical properties of nanoclusters (for example, hydrophily and hydrophoby), and amphiphilic metal nanoclusters can be produced by skillfully controlling the type and amount of ligands; 5 (iii) the functional groups of the surface ligands determine the chemical properties of the metal nanoclusters; thus, fluorescent nanoclusters can be more widely used as probes for detecting various targets. 6,7 Moreover, published studies show that the optical properties of Au and Ag nanoclusters (Ag NCs) protected by thiols are more

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Section: Resultsmentioning

confidence: 99%

The pH-switchable agglomeration and dispersion behavior of fluorescent Ag nanoclusters and its applications in urea and glucose biosensing

et al. 2016

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“…Widespread use of ascorbic and citric acid in the synthesis of silver nanoparticles provides a strong rationale for use of D. bulbifera tuber extract in the synthesis and shaping of silver nanoparticles. [41][42][43] Diosgenin is reported to be a predominant saponin in D. bulbifera 39,44 which might contribute to the surfactant properties of D. bulbifera tuber extract. Plant surfactants are widely used in the synthesis of silver nanoparticles.…”

Section: Discussionmentioning

confidence: 99%

Synthesis of silver nanoparticles using Dioscorea bulbifera tuber extract and evaluation of its synergistic potential in combination with antimicrobial agents

Ghosh¹,

Patil²,

Ahire³

et al. 2012

IJN

211

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Background Development of an environmentally benign process for the synthesis of silver nanomaterials is an important aspect of current nanotechnology research. Among the 600 species of the genus Dioscorea, Dioscorea bulbifera has profound therapeutic applications due to its unique phytochemistry. In this paper, we report on the rapid synthesis of silver nanoparticles by reduction of aqueous Ag + ions using D. bulbifera tuber extract. Methods and results Phytochemical analysis revealed that D. bulbifera tuber extract is rich in flavonoid, phenolics, reducing sugars, starch, diosgenin, ascorbic acid, and citric acid. The biosynthesis process was quite fast, and silver nanoparticles were formed within 5 hours. Ultraviolet-visible absorption spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, and x-ray diffraction confirmed reduction of the Ag + ions. Varied morphology of the bioreduced silver nanoparticles included spheres, triangles, and hexagons. Optimization studies revealed that the maximum rate of synthesis could be achieved with 0.7 mM AgNO 3 solution at 50°C in 5 hours. The resulting silver nanoparticles were found to possess potent antibacterial activity against both Gram-negative and Gram-positive bacteria. Beta-lactam (piperacillin) and macrolide (eryth-romycin) antibiotics showed a 3.6-fold and 3-fold increase, respectively, in combination with silver nanoparticles selectively against multidrug-resistant Acinetobacter baumannii. Notable synergy was seen between silver nanoparticles and chloramphenicol or vancomycin against Pseudomonas aeruginosa , and was supported by a 4.9-fold and 4.2-fold increase in zone diameter, respectively. Similarly, we found a maximum 11.8-fold increase in zone diameter of streptomycin when combined with silver nanoparticles against E. coli , providing strong evidence for the synergistic action of a combination of antibiotics and silver nanoparticles. Conclusion This is the first report on the synthesis of silver nanoparticles using D. bulbifera tuber extract followed by an estimation of its synergistic potential for enhancement of the antibacterial activity of broad spectrum antimicrobial agents.

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“…The absorbance intensity did not change significantly after the 3 rd day indicating that all Ag + ions were turned to nanoparticles [14]. The decrease of λ max may be attributed to the decrease of the nanoparticle size but according to [15] it is possible that nanoparticles undergone intraparticle ripening after complete consumption of the monomer and might become more spherical-like in shape without changing their size. Very high absorbance was also observed in the nanoparticle solution produced by the D. quadricauda on the first experimental day.…”

Section: Resultsmentioning

confidence: 99%

Control over the Biological Synthesis of Ag Nanoparticles by Selection of the Specific Algal Species

Sedláková-Kaduková¹,

Velgosová

Vosátka

et al. 2017

Archives of Metallurgy and Materials

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The application of green synthesis in the nano-science and technology is of great importance in the area of the preparation of various materials. In this work, three selected algal species Parachlorella kessleri, Dictyosphaerium chlorelloides and Desmodesmus quadricauda were successfully used for the preparation of silver nanoparticles (AgNPs). Presence of AgNPs was confirmed by UV-vis spectroscopy and transmission electron microscopy. AgNPs produced by P. kessleri had narrow size distribution and average sizes of 7.6 nm. However, nanoparticle production lasted for long time. Nanoparticle formation by D. chlorelloides was the fastest, although, their average sizes were 23.4 nm with broad size distribution. Nanoparticles produced by D. quadricauda had average sizes 23.9 nm but they were the least stable, aggregated and precipitated from solutions within 3 days. These results confirmed that the size distribution and mean diameter of the nanoparticles, crucial for various applications, can be controlled by the organism selection.

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Size control over spherical silver nanoparticles by ascorbic acid reduction

Cited by 355 publications

References 30 publications

The pH-switchable agglomeration and dispersion behavior of fluorescent Ag nanoclusters and its applications in urea and glucose biosensing

The pH-switchable agglomeration and dispersion behavior of fluorescent Ag nanoclusters and its applications in urea and glucose biosensing

Synthesis of silver nanoparticles using Dioscorea bulbifera tuber extract and evaluation of its synergistic potential in combination with antimicrobial agents

Control over the Biological Synthesis of Ag Nanoparticles by Selection of the Specific Algal Species

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