Simultaneous paramagnetic and persistence-luminescence in GAGG:Ce,Pr nanoparticles synthesized by sol-gel for biomedical applications

Abstract

Nanohybrid systems combining both persistent luminescence and magnetic property are recent breakthroughs in novel multimodal imaging and cancer therapy; however, integrating strategies at a common platform is complex. Herein, we report the synthesis of a Gd3Al5−xGaxO12:Ce3+,Pr3+ (GAGG:Ce,Pr) nanophosphor (x = 1–5) with simultaneous paramagnetic/persistence luminescence via a simple tartaric acid assisted solgel synthesis. Structural analysis revealed the formation of a pure cubic garnet crystal of GAGG:Ce,Pr, which expanded linearly upon gallium incorporation. Moreover, the novel paramagnetic/persistence luminescent material showed the formation of nanoparticles with excellent colloidal stability. Photoluminescence emission analysis showed a broad emission band in the range of λ = 500–750 nm attributed to (5d → 4f) transitions of Ce3+ and a sharp peak centered at λ = 612 nm attributed to electronic transitions (1D2 → 3H4) within Pr3+ upon blue light excitation. In particular, GAGG:Ce-Pr sample with Al:Ga ratio 1:4 yielded persistent luminescence upon blue, UV, and white light excitation at room temperature. Additionally, GAGG:Ce-Pr (x = 4) nanophosphor was paramagnetic and also showed signs of weak ferromagnetism at ambient temperature. Cellular toxicity analysis in different cell lines revealed the relatively safe nature of nanoparticles at the tested concentrations. Overall, in our preliminary analysis, GAGG:Ce-Pr (x = 4) showed the persistent optomagnetic property and low cellular toxicity for potential utilization in multimodal theranostic applications.

Particle size-related limitations of persistent phosphors based on the doped Y3Al2Ga3O12 system

“…For this reason, the synthesis of enough high quality doped-YAGG nanophosphors is still a challenge and the current subject of research. Most of the investigated doped-YAGG nanophosphors are obtained by combustion and Pechini methods 14 , 27 , 28 . Only few authors used a so-called wet-chemical methods such as co-precipitation, hydro- solvo-thermal or sol–gel with the aim of controlling the phase purity, to tailor the particles size and agglomeration degree 15 , 28 – 30 .…”

Synthesis and Biomedical Applications of Lanthanides-Doped Persistent Luminescence Phosphors With NIR Emissions

“…Terminal cancer is often difficult to treat because of the metastasis of cancer cells, so it is necessary to develop an imaging method to track the cancer metastasis in order to achieve more accurate treatment (Sengar et al, 2019 ). Lanthanides-doped PLPs have good promise in tumor tracking and metastasis imaging due to their bright and rechargeable persistent luminescence.…”

Deep red upconversion photoluminescence in Er3+‐doped Yb3Ga5O12 nanocrystalline garnet

“…2 For example, the substitution of Al with Ga in octahedral and tetrahedral sites of the TM-doped and/or RE-doped Y 3 Al 5−x Ga x O 12 or Gd 3 Al 5−x Ga x O 12 garnets may be utilized for tuning of the resulting optical properties due to increment of bond covalence and decrease of crystal field strength affecting the 4f n ↔4f n−1 5d (RE) and d↔d (TM) electronic transitions. [3][4][5] The most famous garnet is Nd 3+ -doped Y 3 Al 5 O 12 (Nd:YAG) used for solid-state lasing either in single crystalline 6 or polycrystalline 7 form. Polycrystalline oxide garnets are commonly prepared by direct synthesis from input single oxides, hydroxides, or carbonates at a high-temperature environment with a resulting crystalline grain size of ≈1 μm.…”

“…Variability of structural sites and cations size allows their relatively easy doping with rare‐earth (RE), transition‐metal (TM), alkali, and alkaline‐earth ions thus allowing the tunability of their resulting properties 2 . For example, the substitution of Al with Ga in octahedral and tetrahedral sites of the TM‐doped and/or RE‐doped Y 3 Al 5− x Ga x O 12 or Gd 3 Al 5− x Ga x O 12 garnets may be utilized for tuning of the resulting optical properties due to increment of bond covalence and decrease of crystal field strength affecting the 4 f n ↔4 f n −1 5 d (RE) and d ↔ d (TM) electronic transitions 3–5 . The most famous garnet is Nd 3+ ‐doped Y 3 Al 5 O 12 (Nd:YAG) used for solid‐state lasing either in single crystalline 6 or polycrystalline 7 form.…”