Agglomeration, isolation and dissolution of commercially manufactured silver nanoparticles in aqueous environments

Elzey, Sherrie; Grassian, Vicki H.

doi:10.1007/s11051-009-9783-y

Cited by 203 publications

(139 citation statements)

References 46 publications

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“…It has been observed numerous times that AgNPs are highly sensitive to air and apparently form a surface silver oxide or silver carbonate layer when exposed to air or aerated water, which may make dissolved oxygen the most relevant oxidant for AgNPs in the environment. 13,14,[51][52][53][54] Indeed, a steep decrease in the Ag + release kinetics of AgNPs has been observed under anaerobic conditions. 13 The overall oxidation reaction for oxidation of Ag 0 by oxygen is 13,35 …”

Section: Silver Nanoparticle Dissolutionmentioning

confidence: 99%

“…8,9,35,54,55 This result is partially explained by the larger surface area of smaller particles on an equivalent mass basis; if more surface atoms are exposed, then more reaction sites are available for oxidation and subsequent dissolution. 9 However, normalizing dissolution rates by surface area cannot fully account for the size-dependent dissolution of nanoparticles.…”

Section: Effects Of Size Shape and Crystallinity On Agnp Dissolutionmentioning

confidence: 99%

“…13,26,35,36,54,79 The influence of aggregation on nanomaterial reactivity has been observed in several cases. 37 Experimental evidence indicates that aggregation quenches dissolution rates of goethite nanorods and galena nanoparticles by an order of magnitude or more.…”

Section: Effects Of Aggregation On Agnp Dissolutionmentioning

confidence: 99%

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Controlled Evaluation of Silver Nanoparticle Dissolution Using Atomic Force Microscopy

Kent

Vikesland

2012

Environ. Sci. Technol.

127

129

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Incorporation of silver nanoparticles (AgNPs) into an increasing number of consumer products has led to concern over the potential ecological impacts of their unintended release to the environment. Dissolution is an important environmental transformation that affects the form and concentration of AgNPs in natural waters; however, studies on AgNP dissolution kinetics are complicated by nanoparticle aggregation. Herein, nanosphere lithography (NSL) was used to fabricate uniform arrays of AgNPs immobilized on glass substrates. Nanoparticle immobilization enabled controlled evaluation of AgNP dissolution in an air-saturated phosphate buffer (pH 7, 25 °C) under variable NaCl concentrations in the absence of aggregation. Atomic force microscopy (AFM) was used to monitor changes in particle morphology and dissolution. Over the first day of exposure to ≥10 mM NaCl, the in-plane AgNP shape changed from triangular to circular, the sidewalls steepened, and the height increased by 6-12 nm. Subsequently, particle height and inplane radius decreased at a constant rate over a 2-week period. Dissolution rates varied linearly from 0.4 to 2.2 nm/d over the 10-550 mM NaCl concentration range tested. NaCl-catalyzed dissolution of AgNPs may play an important role in AgNP fate in saline waters and biological media. This study demonstrates the utility of NSL and AFM for the direct investigation of unaggregated AgNP dissolution.iii Acknowledgements I thank my advisor, Dr. Peter Vikesland, for his insight, guidance, and innovative ideas throughout my time at Virginia Tech, and for giving me the opportunity to work on this research project. He was ready and available to help whenever I needed his input. I also thank the other members of my committee,

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Section: Silver Nanoparticle Dissolutionmentioning

confidence: 99%

Section: Effects Of Size Shape and Crystallinity On Agnp Dissolutionmentioning

confidence: 99%

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Controlled Evaluation of Silver Nanoparticle Dissolution Using Atomic Force Microscopy

Kent

Vikesland

2012

Environ. Sci. Technol.

127

129

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“…Several studies have evaluated the homoagglomeration of nanosilver (nAg) in natural waters, [1][2][3][4][5][6][7][8] providing valuable information on the important factors affecting nanoparticle stability. Generally speaking, increased ionic strength and water hardness will increase agglomeration, [3,5,7,8] organic matter content has been observed to both increase and decrease agglomeration, [3,6,9] and the nature of the particle coating plays a critical role in particle stability.…”

Section: Introductionmentioning

confidence: 99%

Heteroagglomeration of nanosilver with colloidal SiO2 and clay

et al. 2017

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Environmental context. The fate of nanomaterials in the environment is related to their colloidal stability. Although numerous studies have examined their homoagglomeration, their low concentration and the presence of high concentrations of natural particles implies that heteroagglomeration rather than homoagglomeration is likely to occur under natural conditions. In this paper, two state-of-the art analytical techniques were used to identify the conditions under which nanosilver was most likely to form heteroagglomerates in natural waters.Abstract. The environmental risk of nanomaterials will depend on their persistence, mobility, toxicity and bioaccumulation. Each of these parameters is related to their fate (especially dissolution, agglomeration). The goal of this paper was to understand the heteroagglomeration of silver nanoparticles in natural waters. Two small silver nanoparticles (nAg, ,3 nm; polyacrylic acid-and citrate-stabilised) were covalently labelled with a fluorescent dye and then mixed with colloidal silicon oxides (SiO 2 , ,18.5 nm) or clays (,550 nm SWy-2 montmorillonite). Homo-and heteroagglomeration of the nAg were first studied in controlled synthetic waters that were representative of natural fresh waters (50 mg Ag L À1 ; pH 7.0; ionic strength 10 À7 to 10 À1 M Ca) by following the sizes of the nAg by fluorescence correlation spectroscopy. The polyacrylic acid-coated nanosilver was extremely stable under all conditions, including in the presence of other colloids and at high ionic strengths. However, the citrate-coated nanosilver formed heteroaggregates in presence of both colloidal SiO 2 and clay particles. Nanoparticle surface properties appeared to play a key role in controlling the physicochemical stability of the nAg. For example, the polyacrylic acid stabilized nAg-remained extremely stable in the water column, even under conditions for which surrounding colloidal particles were agglomerating. Finally, enhanced dark-field microscopy was then used to further characterise the heteroagglomeration of a citrate-coated nAg with suspensions of colloidal clay, colloidal SiO 2 or natural (river) water.

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“…Aggregation, that is colloidal stability, has a significant influence on the reactivity, bioavailability and pharmacokinetic of NPs, having long been recognized to mediate the toxicity of the particles, as in the case of asbestiform materials, industrial aerosols, and ambient particulate matter [15]. Similarly, oxidative dissolution [16] favors the chemical dissolution of NPs, affecting their persistence and promoting the release of ionic species [12,17,18], which in the case of Ag NPs includes metallic silver (Ag 0 ), ionic silver (Ag + ), and silver chloride (AgCl)) and are responsible for their bactericidal effect [7,9,[19][20][21][22]. The physicochemical state of NPs also plays a role in their interaction with media proteins, and the subsequent nature of the protein corona around the NPs [23,24] (the so-called soft and hard corona), inevitably providing them with new biological identity [25,26], which determines their physiological response including cellular uptake, biodistribution and toxicity [27,28].…”

Section: Introductionmentioning

confidence: 99%

Modeling the Optical Responses of Noble Metal Nanoparticles Subjected to Physicochemical Transformations in Physiological Environments: Aggregation, Dissolution and Oxidation

Piella

Bastús

Puntes

2016

Zeitschrift Für Physikalische Chemie

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Herein, we study how optical properties of colloidal dispersions of noble metal nanoparticles (Au and Ag) are affected by processes such as aggregation and oxidative dissolution. The optical contributions of these processes to the extinction spectra in the UV-vis region are often overlapped, making difficult its interpretation. In this regard, modeling the UV-vis spectra (in particular absorbance curve, peaks position, intensity and full width at half maximum -FWHM) of each process separately offers a powerful tool to identify the transformation of NPs under relevant and complex scenarios, such as in biological media. The proper identification of these transformations is crucial to understand the biological effects of the NPs.

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Agglomeration, isolation and dissolution of commercially manufactured silver nanoparticles in aqueous environments

Cited by 203 publications

References 46 publications

Controlled Evaluation of Silver Nanoparticle Dissolution Using Atomic Force Microscopy

Controlled Evaluation of Silver Nanoparticle Dissolution Using Atomic Force Microscopy

Heteroagglomeration of nanosilver with colloidal SiO2 and clay

Modeling the Optical Responses of Noble Metal Nanoparticles Subjected to Physicochemical Transformations in Physiological Environments: Aggregation, Dissolution and Oxidation

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