1. Department of Fundamental Chemistry; Institute of Chemistry, University of São Paulo; Av. Prof. Lineu Prestes, 748 05508-000 São Paulo Brazil
2. BioPol, Chemistry Department; Federal University of Paraná; P.B. 19032, Centro Politécnico 81531-980 Curitiba Brazil
3. Brazilian Nanotechnology National Laboratory; LME-LNNano- CNPEM; P. B. 6192 13085-903 Campinas Brazil