Lifetime-engineered ruby nanoparticles (Tau-Rubies) for multiplexed imaging of μ-opioid receptors

Xiaohong Yang, Alireza Maleki, Nikolay A. Lipey, Xianlin Zheng, Marina Santiago, Mark Connor, Varun K. A. Sreenivasan, Judith M. Dawes, Yiqing Lu*, Andrei V. Zvyagin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


To address the growing demand for simultaneous imaging of multiple biomarkers in highly scattering media such as organotypic cell cultures, we introduce a new type of photoluminescent nanomaterial termed "tau-ruby"composed of ruby nanocrystals (Al2O3:Cr3+) with tunable emission lifetime. The lifetime tuning range from 2.4 to 3.2 ms was achieved by varying the Cr3+ dopant concentration from 0.8% to 0.2%, affording facile implementation of background-free detection. We developed inexpensive scalable production of tau-ruby characterized by bright emission, narrow spectrum (693 ± 2 nm), and virtually unlimited photostability upon excitation with affordable excitation/detection sources, noncytotoxic and insensitive to microenvironmental fluctuations. By functionalizing the surface of tau-rubies with targeting antibodies, we obtained different biomarkers suitable for multiplexed lifetime imaging. As a proof of principle, three tau-ruby bioprobes, characterized by three mean lifetimes, were deployed to label three μ-opioid receptor species expressed on transfected cancer cells, each fused to a unique epitope, so that three types of cells were lifetime-encoded. Robust decoding of photoluminescent signals that report on each cell type was achieved by using a home-built lifetime imaging system and resulted in high-contrast multiplexed lifetime imaging of the cells.

Original languageEnglish
Pages (from-to)1375-1383
Number of pages9
JournalACS Sensors
Issue number3
Publication statusPublished - 26 Mar 2021


  • background-free imaging
  • biomarkers
  • click-chemistry
  • multiplexed imaging
  • nanoruby
  • photoluminescent nanoparticles
  • time-gated detection


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