Iron Oxide Nanoparticles Labeled with an Excited-State Intramolecular Proton Transfer Dye.
Excited-state intramolecular proton transfer (ESIPT) is a particularly well known reaction that has been very little studied in magnetic environments. In this work, we report on the photophysical behavior of a known ESIPT dye of the benzothiazole class, when in solution with uncoated superparamagnetic iron oxide nanoparticles, and when grafted to silica-coated iron oxide nanoparticles. Uncoated iron oxide nanoparticles promoted the fluorescence quenching of the ESIPT dye, resulting from collisions during the lifetime of the excited state. The assembly of iron oxide nanoparticles with a shell of silica provided recovery of the ESIPT emission, due to the isolation promoted by the silica shell. The silica network gives protection against the fluorescence quenching of the dye, allowing the nanoparticles to act as a bimodal (optical and magnetic) imaging contrast agent with a large Stokes shift.
Multidisciplinary Center of Nanoscience and Micro-nanotechnology, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681., Porto Alegre-RS, CEP, 90619-900, Brazil.
Elisa M N
EM
de Oliveira
Applied Organic Photochemistry, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500., Porto Alegre-RS, CEP, 90650-001, Brazil.
Felipe L
FL
Coelho
Multidisciplinary Center of Nanoscience and Micro-nanotechnology, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681., Porto Alegre-RS, CEP, 90619-900, Brazil.
Mara L
ML
Zanini
Multidisciplinary Center of Nanoscience and Micro-nanotechnology, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681., Porto Alegre-RS, CEP, 90619-900, Brazil.
Ricardo M
RM
Papaléo
Applied Organic Photochemistry, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500., Porto Alegre-RS, CEP, 90650-001, Brazil. leandra.campo@ufrgs.br.
Leandra F
http://orcid.org/0000-0001-6655-3036
LF
Campo
excited-state intramolecular proton transfer; fluorescent probes; magnetic properties; nanoparticles; sol-gel processes