Silver nanoparticles are one of the most widely used commercial nanomaterials. Their dissolution into silver ions makes them potent antimicrobial agents well suited for incorporation into coatings on products such as washing machines and children’s toys. In these applications silver ions are continually produced whether or not there is a need for disinfection. It would be far more efficient to tailor dissolution such that there is only silver ion release when there is contamination. Such control may also help to mitigate the unintended impact of these materials on natural environmental systems. Both goals require a quantitative understanding of silver nanoparticle dissolution. Towards this end we have developed synthetic methodologies that can produce libraries of uniform silver nanoparticles with various shapes, dimensions and surface chemistry. Studies of both the dissolution rate and equilibrium silver ion concentration, or solubility, helped clarify the importance of each parameter. We found a striking shape dependence to the dissolution rate of silver nanoparticles: high aspect ratio particles can have solubilities and dissolution rates up to an order of magnitude larger than spherical materials. Also, silver dissolution can proceed rapidly even when nanocrystals are coated with polymers; however, the surface coverage and polymer type influences both the rate and nanocrystal solubility. In agreement with prior work, we found that across a wide range of diameters, shapes and surfaces that the antimicrobial activity of these materials correlated with the equilibrium concentration of silver ions in a suspension and not with the concentration of total silver or nanocrystals. These results are not only fundamentally interesting, but also of practical importance to the safe and efficient application of silver nanoparticles.

Size and shape dissolution of silver nanoparticles

253rd National Meeting (2017)

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