Positive and negative lattice shielding effects co-existing in Gd (III) ion doped bifunctional upconversion nanoprobes

Chen, Feng, Bu, Wenbo, Zhang, Shengjian, Liu, Xiaohang, Liu, Jianan, Xing, Huaiyong, Xiao, Qingfeng, Zhou, Liangping, Peng, Weijun, Wang, Lianzhou and Shi, Jianlin (2011) Positive and negative lattice shielding effects co-existing in Gd (III) ion doped bifunctional upconversion nanoprobes. Advanced Functional Materials, 21 22: 4285-4294. doi:10.1002/adfm.201101663


Author Chen, Feng
Bu, Wenbo
Zhang, Shengjian
Liu, Xiaohang
Liu, Jianan
Xing, Huaiyong
Xiao, Qingfeng
Zhou, Liangping
Peng, Weijun
Wang, Lianzhou
Shi, Jianlin
Title Positive and negative lattice shielding effects co-existing in Gd (III) ion doped bifunctional upconversion nanoprobes
Journal name Advanced Functional Materials   Check publisher's open access policy
ISSN 1616-301X
1616-3028
Publication date 2011-11-01
Year available 2011
Sub-type Article (original research)
DOI 10.1002/adfm.201101663
Open Access Status Not yet assessed
Volume 21
Issue 22
Start page 4285
End page 4294
Total pages 10
Place of publication Weinheim, Germany
Publisher Wiley
Language eng
Subject 2504 Electronic, Optical and Magnetic Materials
2502 Biomaterials
3104 Condensed Matter Physics
1603 Electrochemistry
Abstract Gadolinium (Gd) doped upconversion nanoparticles (UCNPs) have been well documented as T1-MR and fluorescent imaging agents. However, the performance of Gd3+ ions located differently in the crystal lattice still remains debatable. Here, a well-designed model was built based on a seed-mediated growth technique to systematically probe the longitudinal relaxivity of Gd3+ ions within the crystal lattice and at the surface of UCNPs. We found, for the first time, a nearly 100% loss of relaxivity of Gd3+ ions buried deeply within crystal lattices (> 4 nm), which we named a negative lattice shielding effect (n-LSE) as compared to the positive lattice shielding effect (p-LSE) for the enhanced upconversion fluorescent intensity. As-observed n-LSE was further found to be shell thickness dependent. By suppressing the n-LSE as far as possible, we optimized the UCNPs' structure design and achieved the highest r1 value (6.18 mM-1s-1 per Gd3+ ion) among previously reported counterparts. The potential bimodal imaging application both in vitro and in vivo of as-designed nano-probes was also demonstrated. This study clears the debate over the role of bulk and surface Gd3+ ions in MRI contrast imaging and paves the way for modulation of other Gd-doped nanostructures for highly efficient T1-MR and upconversion fluorescent bimodal imaging.
Formatted abstract
Gadolinium (Gd) doped upconversion nanoparticles (UCNPs) have been  well documented as  T1-MR and fluorescent imaging agents. However, the performance of Gd 3 +  ions located differently in the crystal lattice still remains debatable. Here, a well-designed model was built based on a seed-mediated growth technique to systematically probe the longitudinal relaxivity of Gd 3+ ions within the crystal lattice and at the surface of UCNPs. We found, for  the first time, a nearly 100% loss of relaxivity of Gd 3+  ions buried deeply within crystal lattices ( >  4 nm), which we named a “negative lattice shielding effect” (n-LSE) as compared to the “positive lattice shielding effect” (p-LSE) for the enhanced upconversion fl uorescent intensity. As-observed n-LSE was further found to be shell thickness dependent. By suppressing the n-LSE as far as possible, we optimized the UCNPs’ structure design and achieved the highest  r1  value (6.18 mM-1 s-1  per Gd 3+  ion) among previously reported counterparts. The potential bimodal imaging application both in vitro and in vivo of as-designed nano-probes was also demonstrated. This study clears the debate over the role of bulk and surface Gd 3+  ions in MRI contrast imaging and paves the way for modulation of other Gd-doped nanostructures for highly efficient  T1-MR and upconversion fluorescent bimodal imaging.
Keyword Mri Contrast Agent
In-Vivo
Upconverting Nanoparticles
Nayf4 Nanocrystals
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID 50972154
2011CB707905
10430712800
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
Official 2012 Collection
 
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