Three strategies to stabilise nearly monodispersed silver nanoparticles in aqueous solution
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NANO EXPRESS
Open Access
Three strategies to stabilise nearly monodispersed silver nanoparticles in aqueous solution Amadeus PZ Stevenson1, Duani Blanco Bea2, Sergi Civit3, Sonia Antoranz Contera1,4, Alberto Iglesias Cerveto2 and Sonia Trigueros1,4*
Abstract Silver nanoparticles are extensively used due to their chemical and physical properties and promising applications in areas such as medicine and electronics. Controlled synthesis of silver nanoparticles remains a major challenge due to the difficulty in producing long-term stable particles of the same size and shape in aqueous solution. To address this problem, we examine three strategies to stabilise aqueous solutions of 15 nm citrate-reduced silver nanoparticles using organic polymeric capping, bimetallic core-shell and bimetallic alloying. Our results show that these strategies drastically improve nanoparticle stability by distinct mechanisms. Additionally, we report a new role of polymer functionalisation in preventing further uncontrolled nanoparticle growth. For bimetallic nanoparticles, we attribute the presence of a higher valence metal on the surface of the nanoparticle as one of the key factors for improving their long-term stability. Stable silver-based nanoparticles, free of organic solvents, will have great potential for accelerating further environmental and nanotoxicity studies. PACS: 81.07.-b; 81.16.Be; 82.70.Dd. Keywords: silver nanoparticles, stability, functionalisation, monodispersed, aging, toxicity.
Background Metal nanoparticles have generated great interest for applications in physics, materials, chemistry and biomedical sciences in plasmonics [1], biosensing [2-4], nanomedicine [5-7], nanoelectronics [8], catalysis [9,10], magnetic fluids [11] and dye-based solar cells [12] due to their chemical, electronic, optical and magnetic properties. These applications depend on the availability of homogeneous nanoparticles of controlled size and shape, which remain stable in their complex target environments [13,14]. For example, metal nanoparticles exhibit surface plasmon resonance in the visible spectrum range, resulting in light scattering and characteristic absorbance peaks whose location and width depend on the type of metal, size and shape of the nanostructure and the medium they are immersed in [15-19]. Interactions between nanoparticles and biological matter * Correspondence: [email protected] 1 Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, UK Full list of author information is available at the end of the article
will also depend on their size, shape and surface charge as they interact with different organisms [20]. Silver and gold nanoparticles have attracted great interest for many applications due to their strong plasmonic properties and to the availability of methods for synthesis [21,22]. The colloidal method has been extensively used due to the ability to synthesise nanoparticles directly in aqueous solution [23]. However, controlling the size and shape of metal nanoparticles remains cha
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