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Iron Oxide Nanoparticles Labeled with an Excited‐State Intramolecular Proton Transfer Dye
Author(s) -
de Oliveira Elisa M. N.,
Coelho Felipe L.,
Zanini Mara L.,
Papaléo Ricardo M.,
Campo Leandra F.
Publication year - 2016
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201600472
Subject(s) - benzothiazole , photochemistry , nanoparticle , quenching (fluorescence) , iron oxide nanoparticles , fluorescence , chemistry , excited state , intramolecular force , magnetic nanoparticles , iron oxide , stokes shift , oxide , materials science , nanotechnology , organic chemistry , physics , quantum mechanics , nuclear physics
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.