Citrate Stabilized Silver Nanoparticles: Study of Crystallography and Surface Properties

Citrate Stabilized Silver Nanoparticles: Study of Crystallography and Surface Properties

Nabraj Bhattarai (Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA), Subarna Khanal (Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA), Pushpa Raj Pudasaini (Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA), Shanna Pahl (Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA) and Dulce Romero-Urbina (Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA)
Copyright: © 2011 |Pages: 14
DOI: 10.4018/ijnmc.2011070102
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Abstract

Citrate stabilized silver (Ag) colloidal solution were synthesized and characterized for crystallographic and surface properties by using transmission electron microscopy (TEM) and zeta potential measurement techniques. TEM investigation depicted the size of Ago ranges from 5 to 50 nm with smaller particles having single crystal structure while larger particles with structural defects (such as multiply twinned, high coalescence and Moire patterns). ?-potential measurement confirms the presence of Ag+ in nAg stock solution. The shift in ?-potential measurement by +25.1 mV in the filtered solution suggests the presence of Ag+ in Ago nanoparticles.
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1. Introduction

The application of nanoscale materials and structures, usually ranging from 1 to 100 nanometers (nm), is an emerging area of nanoscience and nanotechnology. Nanomaterials may provide solutions to technological and environmental challenges in the areas of solar energy conversion (Atwater & Polman, 2010; Brown et al., 2011), catalysis (Bhattarai, Casillas, Ponce, & Jose-Yacaman, 2012; Cuenya, 2010; Khanal, Casillas, Velazquez-Salazar, Ponce, & Jose-Yacaman, 2012; Raji, Chakraborty, & Parikh, 2012; Yuan, Yan, & Dyson, 2012), medicine (Conde, Doria, & Baptista, 2012; Davis et al., 2010), and water treatment (Dankovich & Gray, 2011; Kaegi et al., 2011). In recent years, noble metal nanoparticles like gold (Au), silver (Ag) etc. are of special interest due to their plasmonics properties, especially in photovoltaic (Pudasaini & Ayon, 2012; Tan, Santbergen, Smets, & Zeman, 2012), medicine (Conde et al., 2012; Davis et al., 2010; Nykypanchuk, Maye, van der Lelie, & Gang, 2008), and bio-imaging (Hutter & Maysinger, 2011; Lee et al., 2006; Y. Liu, Miyoshi, & Nakamura, 2007). Silver nanoparticles are extraordinarily efficient in absorbing and scattering light and, unlike many dyes and pigments, have a color that depends on the size and the shape of the nanostructures.

The interest in Ag nanoparticles and their applications has increased mainly due to their important antimicrobial, antifungal, antibacterial, antiviral activities (Jung et al., 2008; J. Liu, Yu, Yin, & Chao, 2012), allowing their use in several medical applications. Colloidal silver is of particular interest given its distinctive properties, such as good conductivity, chemical stability, catalytic and enhanced antibacterial activity. There is an increasing interest in understanding the relationship between the physical and chemical properties of nano silver and their potential risk to the environment and human health. The mechanism of the antimicrobial action of silver ions is closely related to their interaction with thiol (sulfhydryl) groups (Toshima et al., 1991), although other target sites remain a possibility. Amino acids, such as cysteine, and other compounds containing thiol groups, such as sodium thioglycolate, neutralized the activity of silver against bacteria (Liau, Read, Pugh, Furr, & Russell, 1997). On the other hand, disulfide bond-containing amino acids, non-sulfur-containing amino acids, and sulfur-containing compounds, such as cystathione, cysteic acid, L-methionine, taurine, sodium bisulfates, and sodium thiosulfate, were all unable to neutralize the activity of silver ions. These and other findings imply that the interaction of silver ions with thiol groups in enzymes and proteins play an essential role in its antimicrobial action, although other cellular components, like hydrogen bonding, may also be involved.

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