NaGdF₄:Eu³⁺ Nanoparticles for Enhanced X‑ray Excited Optical Imaging

X-ray luminescent nanoparticles (NPs), including lanthanide fluorides, have been evaluated for application to deep tissue in vivo molecular imaging using optical tomography. A combination of high material density, higher atomic number and efficient NIR luminescence from compatible lanthanide dopant ions indicates that particles that consist of ALnF₄ (A = alkaline, Ln = lanthanide element) may offer a very attractive class of materials for high resolution, deep tissue imaging with X-ray excitation. NaGdF₄:Eu³⁺ NPs produced an X-ray excited luminescence that was among the most efficient of nanomaterials that have been studied thus far. We have systematically studied factors such as (a) the crystal structure that changes the lattice environment of the doped Eu³⁺ ions within the unit cell; and extrinsic factors such as (b) a gold coating (with attendant biocompatibility) that couples to a plasmonic excitation, and (c) changes in the NPs surface properties via changes in the pH of the suspending mediumall with a significant impact on the X-ray excited luminescence of NaGdF₄:Eu³⁺NPs. The luminescence from an optimally doped hexagonal phase NaGdF₄:Eu³⁺ nanoparticle was 25% more intense compared to that of a cubic structure. We observed evidence of plasmonic reabsorption of midwavelength emission by a gold coating on hexagonal NaGdF₄:Eu³⁺ NPs; fortunately, the NaGdF₄:Eu³⁺ @Au core–shell NPs retained the efficient ⁵<i>D</i>₀<i>→</i>⁷<i>F</i>₄ NIR (692 nm) luminescence. The NaGdF₄:Eu³⁺ NPs exhibited sensitivity to the ambient pH when excited by X-rays, an effect not seen with UV excitation. The sensitivity to the local environment can be understood in terms of the sensitivity of the excitons that are generated by the high energy X-rays (and not by UV photons) to crystal structure and to the surface state of the particles

Additional file 2 of Cherenkov luminescence measurements with digital silicon photomultipliers: a feasibility study

Comparison of measurements at same temperature. Distribution of the differences in the count rates measured in two independent acquisitions performed at the same temperature (12.5¹0.4 °C), for all dies. Labels and legend follow Fig. 9, and plot positions refer to die positions in the die (Fig. 2-center). (PNG 44 kb

Boletín de Segovia: Número 56 - 1850 mayo 13

Copia digital. Madrid : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, 200

Additional file 4 of Cherenkov luminescence measurements with digital silicon photomultipliers: a feasibility study

Test of correction algorithm, left. Application of the correction algorithm to the test set without the source, for all dies. Error bars are taken from Table 2. Labels and legend follow Fig. 11-left, and plot positions refer to die positions in the die (Fig. 2-center). (PNG 54 kb