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Highly Luminescent Folate‐Functionalized Au 22 Nanoclusters for Bioimaging
Author(s) -
Pyo Kyunglim,
Ly Nguyen Hoang,
Yoon Sook Young,
Shen Yiming,
Choi Seon Young,
Lee So Yeong,
Joo SangWoo,
Lee Dongil
Publication year - 2017
Publication title -
advanced healthcare materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.288
H-Index - 90
eISSN - 2192-2659
pISSN - 2192-2640
DOI - 10.1002/adhm.201700203
Subject(s) - nanoclusters , luminescence , biocompatibility , materials science , conjugated system , quantum yield , photochemistry , cluster (spacecraft) , nanotechnology , chemistry , nuclear chemistry , fluorescence , organic chemistry , physics , optoelectronics , quantum mechanics , computer science , programming language , polymer
Gold nanoclusters are emerging as new materials for biomedical applications because of promises offered by their ultrasmall size and excellent biocompatibility. Here, the synthesis and optical and biological characterizations of a highly luminescent folate‐functionalized Au 22 cluster (Au 22 ‐FA) are reported. The Au 22 ‐FA clusters are synthesized by functionalizing the surface of Au 22 (SG) 18 clusters, where SG is glutathione, with benzyl chloroformate and folate. The functionalized clusters are highly water‐soluble and exhibit remarkably bright luminescence with a quantum yield of 42%, significantly higher than any other water‐soluble gold clusters protected with thiolate ligands. The folate groups conjugated to the gold cluster give rise to additional luminescence enhancement by energy transfer sensitization. The brightness of Au 22 ‐FA is found to be 4.77 mM −1 cm −1 , nearly 8‐fold brighter than that of Au 22 (SG) 18 . Further biological characterizations have revealed that the Au 22 ‐FA clusters are well‐suited for bioimaging. The Au 22 ‐FA clusters exhibit excellent photostability and low toxicity; nearly 80% cell viability at 1000 ppm of the cluster. Additionally, the Au 22 ‐FA clusters show target specificity to folate‐receptor positive cells. Finally, the time‐course in vivo luminescence images of intravenous‐injected mice show that the Au 22 ‐FA clusters are renal‐clearable, leaving only 8% of them remained in the body after 24 h post‐injection.