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Type: Artigo de periódico
Title: The use of molecular probes for the characterization of dispersions of functionalized silica nanoparticles
Author: Arce, VB
Bertolotti, SG
Oliveira, FJVE
Airoldi, C
Gonzalez, MC
Allegretti, PE
Martire, DO
Abstract: Butoxylated silica nanoparticles (BSN) were prepared by esterification of the silanol groups of fumed silica nanoparticles with butanol and characterized by (13)C and (29)Si NMR and thermogravimetry. The molecular probes benzophenone (BP) and safranine-T were used to investigate the BSN suspensions in water: acetonitrile. Laser flash-photolysis experiments at lambda(exc)=266nm performed with BSN suspended in acetonitrile:aqueous phosphate buffer supported previous results of our group obtained by time-resolved phosphorescence experiments and showed that only free and adsorbed excited triplet states of BP and diphenylketyl radicals contribute to the signals. The UV-vis spectroscopic and photophysical properties of safranine-T are strongly solvent-dependent. Thus, the analysis of the emission spectra and fluorescence lifetimes yielded information on the localization of this probe molecule in suspensions of BSN and of the bare silica nanoparticles. The values of the equilibrium constant for the adsorption of the ground-state safranine-T on the particles were found to be (9.2 +/- 0.8) x 10(4), (7.2 +/- 0.8) x 10(5), and (3.0 +/- 0.1) X 10(4) for the BSN in 1: 1 acetonitrile:water, SiO(2) in 1:1 acetonitrile:water, and SiO(2) in acetonitrile, respectively. (C) 2009 Elsevier B.V. All rights reserved.
Subject: Functionalized silica nanoparticles
Laser flash-photolysis
Ketyl radical
Single photon counting
Country: Inglaterra
Editor: Pergamon-elsevier Science Ltd
Rights: fechado
Identifier DOI: 10.1016/j.saa.2009.01.018
Date Issue: 2009
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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