Multispectral Emissions of Lanthanide-Doped Gadolinium Oxide Nanophosphors for Cathodoluminescence and Near-Infrared Upconversion/Downconversion Imaging

Abstract

Comprehensive imaging of a biological individual can be achieved by utilizing the variation in spatial resolution, the scale of cathodoluminescence (CL), and near-infrared (NIR), as favored by imaging probe Gd2O3 co-doped lanthanide nanophosphors (NPPs). A series of Gd2O3:Ln3+/Yb3+ (Ln3+: Tm3+, Ho3+, Er3+) NPPs with multispectral emission are prepared by the sol-gel method. The NPPs show a wide range of emissions spanning from the visible to the NIR region under 980 nm excitation. The dependence of the upconverting (UC)/downconverting (DC) emission intensity on the dopant ratio is investigated. The optimum ratios of dopants obtained for emissions in the NIR regions at 810 nm, 1200 nm, and 1530 nm are applied to produce nanoparticles by the homogeneous precipitation (HP) method. The nanoparticles produced from the HP method are used to investigate the dual NIR and CL imaging modalities. The results indicate the possibility of using Gd2O3 co-doped Ln3+/Yb3+ (Ln3+: Tm3+, Ho3+, Er3+) in correlation with NIR and CL imaging. The use of Gd2O3 promises an extension of the object dimension to the whole-body level by employing magnetic resonance imaging (MRI).

Structural and optical characterisation of silanised Dy-doped-Gd2O3 NPs

“…According to some authors, carbonates form during the calcination process under natural atmospheric conditions. 34,35 However, it was impossible to observe their associated peaks in XRD, which suggests that they are on the nanoparticle surfaces at trace levels. This scenario is consistent with our results of thermogravimetric analysis (see the ESI, † S2).…”

Recent Advancements in Ln‐Ion‐Based Upconverting Nanomaterials and Their Biological Applications

“…In large scale synthesis of multicomponent materials, the sol–gel method is inexpensive, facile, and can be performed at relatively low temperature . It is a wet‐chemical method which involves rapid hydrolysis of a molecular precursor followed by polycondensation reactions.…”

“…This method allows the production of material with well‐defined shape, homogeneity, and high‐purity. Another advantage of this process is that the mixed reagents can be controlled at the subatomic level resulting in increased reaction time by decreasing the reaction temperature . Barrera et al synthesized highly crystalline Ln 3+ ‐doped KLu(WO 4 ) 3 nanocrystal (Ln 3+ = Ho 3+ , Tm 3+ , Yb 3+ ) by sol–gel modified Pechini method.…”

Enhancing near‐infrared fluorescence intensity and stability of PLGA‐b‐PEG micelles by introducing Gd‐DOTA at the core boundary

“…[1][2][3][4] Most NIR-II probes comprise inorganic compounds, such as rare-earth-doped ceramic nanoparticles, quantum dots, or graphene. [5][6][7][8] Several organic probes have been developed, including a structure composed of polymeric micelles with NIR-II dye (IR-1061) encapsulated inside the micelle core. 4,[9][10][11] IR-1061 dye is rather sensitive to water and is often encapsulated in a micellar structure to prevent it from interacting with water.…”