Lanthanide-chelate silica nanospheres as robust multicolor Vis-NIR tags

Abstract

Different lanthanide chelates have been simultaneously embedded in a silica matrix yielding bright dual-mode lanthanide doped nanospheres which are uniform in size distribution, tunable, photostable, and leakage free. Depending on the chelate combination, two color emission with a single light source or tunable emission with multiple sources is obtained.

A comparative study of non-covalent encapsulation methods for organic dyes into silica nanoparticles

“…A slight shift and different shapes in the excitation band of the fluorescein was observed which is attributed to the incorporation of the fluorescent dye and its interaction with the silica network. Those results indicated that the silica encapsulation by microemulsion was suitable for encapsulation of hydrophilic chromophores and was consistent with the literature [ 15 , 51 - 54 ]. It was therefore decided after those fluorescence measurements (Figure 4 ) that no better encapsulation could be achieved by other processes and no further investigation of those two dyes were tested.…”

A Gadolinium Complex Confined in Silica Nanoparticles as a Highly Efficient T1/T2 MRI Contrast Agent

“…According to this theory, the steep decrease of r 1 after its local maximum can be attributed to long correlation times τ r and/or τ of at least a few ns. By contrast, the monotonous increase of r 1 as ν I goes to zero is a peculiarity of some nanosystems,6c, d which has not yet been explained in detail, but is probably due to a restricted motion of the Gd chelate and of the water molecules combined to the water permeable structure of the silica NPs 20. The high‐frequency values of r 2 , which are more than twice as large as the r 1 maximum, cannot either be explained by the standard relaxivity theory.…”

“…By contrast, the monotonous increase of r 1 as n I goes to zero is a peculiarity of some nanosystems, [6c, d] which has not yet been explained in detail, but is probably due to a restricted motion of the Gd chelate and of the water molecules combined to the water permeable structure of the silica NPs. [20] The high-frequency values of r 2 , which are more than twice as large as the r 1 maximum, cannot either be explained by the standard relaxivity theory. They should likely be ascribed to the combined effects of the inhomogeneities of the magnetic field created by the magnetized NPs and the exchange of water between these NPs and the bulk.…”

“…Notably luminescent complexes of visible and/or near-IR Ln III emitters [19] can be noncovalently incorporated in silica NPs. [20] To obtain the multimodal MRI/ optical nanoparticles, during the preparation of NPGd25, 3À for which a strong near-IR emission has been reported. [21] These NPs show high r 1 and r 2 relaxivities together with a detectable luminescence in the near-IR region even at this low Yb III concentration (see Figure S4 in the Supporting Information).…”

“…The versatile incorporation of lanthanide complexes in silica NPs is particularly well suited for the development of multimodal probes. Notably luminescent complexes of visible and/or near‐IR Ln III emitters19 can be noncovalently incorporated in silica NPs 20. To obtain the multimodal MRI/optical nanoparticles, during the preparation of NPGd25, 5 % of [Gd(ebpatcn)(H 2 O)] is replaced by [Yb(thqtcn‐SO 3 )(H 2 O] 3− for which a strong near‐IR emission has been reported 21.…”