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Amine‐Functionalized Silica Nanoparticles Incorporating Covalently Linked Visible‐Light‐Excitable Eu 3+ Complexes: Synthesis, Characterization, and Cell‐Uptake Studies
Author(s) -
Francis Biju,
Neuhaus Bernhard,
Reddy M. L. P.,
Epple Matthias,
Janiak Christoph
Publication year - 2017
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201700240
Subject(s) - chemistry , nanoparticle , covalent bond , surface modification , photochemistry , luminescence , carbazole , amine gas treating , nanotechnology , organic chemistry , materials science , optoelectronics
We report the synthesis, characterization, photophysical investigations, and cell‐uptake studies of luminescent silica nanoparticles incorporating covalently linked visible‐light‐excitable Eu 3+ complexes. Visible‐light excitation was accomplished by using highly conjugated carbazole‐based β‐diketonate ligands. Covalent incorporation of the Eu 3+ complexes into the silica nanoparticles was achieved by modification of the bidentate phosphine oxide 4,6‐bis(diphenylphosphoryl)‐10 H ‐phenoxazine ( DPOXPO ), which was used as the neutral donor for the Eu 3+ ion. The surface amine functionalization of the nanoparticles was carried out using aminopropyltriethoxysilane (APTES). The prepared nanoparticles ( Eu@Si‐OH and Eu@Si‐NH2 ) are around 35–40 nm in diameter, monodisperse, stable in aqueous dispersion, and also retain the luminescent properties of the incorporated Eu 3+ complex. The synthesized nanoparticles exhibit a promising luminescence quantum yield of 38 % and an excited‐state lifetime of 638 µs at physiological pH. The photobleaching experiments revealed that the developed nanoparticles are more photostable than the parent Eu 3+ complex 1 . In vitro experiments with Eu@Si‐NH2 nanoparticles on HeLa cells showed that they are biocompatible and are readily taken up by cells.