Near Infrared-Emitting Cr3+/Eu3+ Co-doped Zinc Gallogermanate Persistence Luminescent Nanoparticles for Cell Imaging

Abstract

Near infrared (NIR)-emitting persistent luminescent nanoparticles have been developed as potential agents for bioimaging. However, synthesizing uniform nanoparticles with long afterglow for long-term imaging is lacking. Here, we demonstrated the synthesis of spinel structured Zn3Ga2Ge2O10:Cr3+ (ZGGO:Cr3+) and Zn3Ga2Ge2O10:Cr3+,Eu3+ (ZGGO:Cr3+,Eu3+) nanoparticles by a sol-gel method in combination with a subsequent reducing atmosphere-free calcination. The samples were investigated via detailed characterizations by combined techniques of XRD, TEM, STEM, selected area electron diffraction, photoluminescence excitation (PLE)/photoluminescence (PL) spectroscopy, and temperature-dependent PL analysis. The single-crystalline nanoparticles are homogeneous solid solution, possessing uniform cubic shape and lateral size of ~ 80–100 nm. Upon UV excitation at 273 nm, ZGGO:Cr3+,Eu3+ exhibited a NIR emission band at 697 nm (2E → 4A2 transition of distorted Cr3+ ions in gallogermanate), in the absence of Eu3+ emission. NIR persistent luminescence of the sample can last longer than 7200 s and still hold intense intensity. Eu3+ incorporation increased the persistent luminescence intensity and the afterglow time of ZGGO:Cr3+, but it did not significantly affect the thermal stability. The obtained ZGGO:Cr3+,Eu3+-NH2 nanoparticles possessed an excellent imaging capacity for cells in vitro.

Influences of copper–potassium ion exchange process on the optical bandgaps and spectroscopic properties of Cr3+/Yb3+ co-doped in lanthanum aluminosilicate glasses

“…6, we present the visible emission spectra under excitation 343 nm of all these glass samples with two peaks at about 488 and 653 nm, which are assigned to the 2 T 2 / 4 A 2g and 4 T 2g ( 4 F) / 4 A 2g transitions of Cr 3+ . 17,43,45 As shown, the visible emission intensities of Cr 3+ /Yb 3+ co-doped bands centered at 488 and 653 nm signicantly increased with the increase in salt concentration ratio p from 0.18 to 0.54. 47 Interestingly, the peak at 488 nm of Cr 3+ under 343 nm excitation has a slight blue-shi of about 8 nm.…”

“…These increments may be ascribed to the local surface plasmon resonance (LSPR) of copper ions 44 and the crystal eld variation caused by copper ions. 17,43,45 Moreover, the intensities of two absorption spectra bands centered at 306 nm and 878 nm also increased signicantly, which conrms the existence and the role of Cu + and Cu 2+ , respectively, 46 in the absorption spectra of Cr 3+ /Yb 3+ co-doped. The Cu + formed and exists in silicate glass due to reducing of Cu 2+ .…”

“…For the SALBK-1Cr2.5Yb-0Cu glass sample, we can observe three absorption peaks bands centered at 470, 650, and 878 nm, which is evidence that they are from the 4 A 2g / 4 T 1g (F), 4 A 2g / 4 T 2g (F) and 4 A 2g / 2 E transitions of Cr 3+ . 17,42,43 In addition, with the increase in salt concentration ratio p from 0.18 to 0.54, the emission intensities of Cr 3+ /Yb 3+ co-doped bands centered at 470, 650 nm, and 878 nm strongly increased. These increments may be ascribed to the local surface plasmon resonance (LSPR) of copper ions 44 and the crystal eld variation caused by copper ions.…”

<p>A brief review of cytotoxicity of nanoparticles on mesenchymal stem cells in regenerative medicine</p>

“…PLNPs exhibit unprecedented advantages in stem cells tracking due to the following unique features 104. The most important is that PLNPs can remain glowing for hours or even days after excitation is stopped,105–107 which makes long-term imaging possible without in situ excitation. The other is that PLNPs have excellent signal-to-noise ratios, and can be distinguished from normal tissue autofluorescence.…”

Rare earth free bright and persistent white light emitting zinc gallo-germanate nanosheets: technological advancement to fibers with enhanced quantum efficiency

“…Most of the research is focused on the exploration of Zn 3 Ga 2 Ge 2 O 10 (ZGG) doped with Mn 2+ , Bi 3+ , and Cr 3+ for their PL and/or PerL properties owing to its low synthesis temperature, high stability, excellent bio-compatibility, non-toxicity, and moderate conductivity. 1,4,18,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] However, there are very few reports on intrinsic self-activated bluish white emission in bulk/microcrystalline ZGG. 29 Although Li et al 18 have demonstrated the visible PL in ZGG nanoparticles, their emission zone lies more in the green region which lacks commercial usage for day to day activity compared to white light emitting materials.…”