Photophysics and Photochemistry to Differentiate between Metal Nanoparticles in Mixtures: an Analytical Strategy

PACIONI, NATALIA L.; SALAS, SANTIAGO D.; VEGLIA, VIVIANA V.

Sarasota

Encuentro; 22nd Winter Inter-American Photochemical Society Meeting; 2013

Research on environmental and health consequences that could be produced by the increasing use of nanomaterials (eg. metal nanoparticles, NM) is still in their infancy. The success of these research fields as well as the establishment of new regulations for these emerging pollutants is closely related to the availability of reliable analytical methods that permit to distinguish and quantify different NM. Nevertheless, there is still a lack of standarized analytical methods to detect and evaluate NM in environmental samples. Regarding to this, one of the main challenges we currently are facing is the development of strategies that allow us to detect these nanoparticles and to facilitate their quantification in environmental studies.[1] Among their unique properties, NM like gold and silver have a characteristic extinction in the UV-visible region named as Surface Plasmon Resonance Band (SPB) that is sensitive to several factors such as size, shape, coverage and interparticle distance; and that has been proved to produce interesting light-induced phenomena on molecules in the vicinity of the metal surface.[2] Presented here are some examples of developing analytical strategies in our group to distinguish between different gold and silver nanoparticles in mixtures. These methods are based on the specific and/or selective interaction between the NM and, molecular and supramolecular switches that induces variations on the photophysics or photochemistry of the interacting systems. For example, these modifications are reflected by changes either on the nanoparticle SPB or on the spectroscopic properties such as absorption, fluorescence, induced circular dichroism of the interacting species observed as a shift in the position of the signals and either enhancement or decrease of their intensity. References [1] Ferreira da Silva, B. et al. TrAC Trends in Anal. Chem. 2011, 30, 528. Weinberg, H. et al. TrAC Trends in Anal. Chem. 2011, 30, 72; H Zänker et al. Annu. Rev. Anal. Chem. 2012, 5, 107. [2] Anger, P et al. Phys. Rev. Lett. 2006, 94,4; Pacioni, N. L. et al, J. Am. Chem. Soc. 2010, 132, 6298; Stamplecoskie, K.G. et al J. Am. Chem. Soc. 2011, 133, 9160; Stamplecoskie, K.G. et al, J. Phys. Chem. C, 2011, 115, 1403.