Highly Luminescent Folate-Functionalized Au22 Nanoclusters for Bioimaging

Kyunglim Pyo, Nguyen Hoang Ly, Sook Young Yoon, Yiming Shen, Seon Young Choi, So Yeong Lee, Sang Woo Joo, Dongil Lee

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Abstract

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 Au22 cluster (Au22-FA) are reported. The Au22-FA clusters are synthesized by functionalizing the surface of Au22(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 Au22-FA is found to be 4.77 mM−1 cm−1, nearly 8-fold brighter than that of Au22(SG)18. Further biological characterizations have revealed that the Au22-FA clusters are well-suited for bioimaging. The Au22-FA clusters exhibit excellent photostability and low toxicity; nearly 80% cell viability at 1000 ppm of the cluster. Additionally, the Au22-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 Au22-FA clusters are renal-clearable, leaving only 8% of them remained in the body after 24 h post-injection.

Original languageEnglish
Article number1700203
JournalAdvanced healthcare materials
Volume6
Issue number16
DOIs
Publication statusPublished - 2017 Aug 23

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All Science Journal Classification (ASJC) codes

  • Biomaterials
  • Biomedical Engineering
  • Pharmaceutical Science

Cite this

Pyo, K., Ly, N. H., Yoon, S. Y., Shen, Y., Choi, S. Y., Lee, S. Y., Joo, S. W., & Lee, D. (2017). Highly Luminescent Folate-Functionalized Au22 Nanoclusters for Bioimaging. Advanced healthcare materials, 6(16), [1700203]. https://doi.org/10.1002/adhm.201700203