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    Spheres vs. rods: The shape of gold nanoparticles influences aggregation and deposition behavior

    Year: 2013

    Journal: Chemosphere Volume 91, Issue 1, March 2013, Pages 93–98, 20130402

    Authors: A.R.M. Nabiul Afrooz 1, Sean T. Sivalapalan 2, Catherine J. Murphy 2, Saber M. Hussain 3, John J. Schlager 4, Navid B. Saleh 1

    Last authors: Navid B. Saleh

    Organizations: 1 Department of Civil and Environmental Engineering, University of South Carolina, Columbia, SC 29208, USA 2 Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA 3 Human Effectiveness Directorate, 711 Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, OH 45431, USA 4 Molecular Bioeffects Branch, 711 Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, OH 45431, USA

    Country: USA, US, United States, United States of America, America

    The influence of shape on nanomaterial aggregation and deposition was systematically studied with poly-acrylic acid (PAA) coated uniform-sized gold nanospheres (AuNSs) and nanorods (AuNRs). Time resolved dynamic light scattering was employed to study their aggregation kinetics in a wide range of mono- and di-valent electrolyte conditions. Results indicated that PAA coated AuNSs have higher aggregation propensity compared to anisotropic PAA coated AuNRs, as observed through critical coagulation concentration (CCC). The CCC values were estimated as 50 mM NaCl and 1.8 mM CaCl2 for AuNS, which showed substantial increase to 250 mM NaCl and 7 mM CaCl2 for anisotropic AuNRs. Though electrokinetic behavior showed similar surface potential for the spherical and rod-shaped materials, the geometric differences between the samples have likely resulted in unique conformation of the PAA coatings, leading to different magnitudes of steric hindrances and hence yielding the observed aggregation behavior. The deposition kinetics was monitored using the quartz crystal microbalance with dissipation technique. AuNRs showed relatively slower deposition compared to AuNSs for low electrolytes concentrations. With the increase in electrolyte concentration, the differences in deposition rates between spheres and rods diminished. The results from this study showed that the shape of nanomaterials can influence interfacial properties and result in unique aggregation and deposition behavior under typical aquatic conditions.