Comparative Study of Upconverting Nanoparticles with Various Crystal Structures, Core/Shell Structures, and Surface Characteristics

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• 作者：Yong Il Park ; Sang Hwan Nam ; Jeong Hyun Kim ; Yun Mi Bae ; Byeongjun Yoo ; Hyung Min Kim ; Ki-Seok Jeon ; Hyo Sun Park ; Joon Sig Choi ; Kang Taek Lee ; Yung Doug Suh ; Taeghwan Hyeon
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：February 7, 2013
• 年：2013
• 卷：117
• 期：5
• 页码：2239-2244
• 全文大小：384K
• 年卷期：v.117,no.5(February 7, 2013)
• ISSN：1932-7455

文摘

Upconverting nanoparticles (UCNPs) have been studied as novel bioimaging probes owing to the absence of autofluorescence and excellent photostability. For practical applications, biocompatible UCNPs with high upconversion efficiency, bright luminescence, and good colloidal stability are desirable. Herein, we report a quantitative and systematic study on the upconversion luminescence from a set of NaYF₄:Yb³⁺,Er³⁺-based nanoparticles by varying crystal structures, core/shell structures, and surface ligands. Upconversion luminescent properties in colloidal solution and at the single-particle level were examined. Hexagonal-phase core/shell UCNPs exhibited the most intense luminescence among various structures, while the excellent photostability was observed in all different types of UCNPs. To optimize the biomedical imaging capability of UCNPs, various surface coating strategies were tested. By quantitative spectroscopic measurements of surface-modified UCNPs in water, it was suggested that encapsulation with polyethylene glycol (PEG)-phospholipid was found to be effective in retaining both upconversion luminescence intensity and dispersibility in aqueous environment. Finally, UCNPs with different crystal structures were applied and compared in live cells.