Upconversion Nanoformulation for Functional Imaging

Surojit Chattopadhyay*, Sandip Ghosh, Najim Akhtar, De Ming Yang, Chuan Lin Chen, Ren Shyan Liu

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Upconversion nanoparticles (UCNPs) are excited in the near infrared (NIR) biological transparency window, but emits anti-Stokes shifted photons in the visible that are extremely photostable and ideally suited for biomedical imaging. First, we synthesize a UCNP-mOrange fluorescent protein conjugate that forms a Forster resonance energy transfer (FRET) pair with UCNP as the donor and mOrange as the acceptor to report intracellular pH by fluorescence imaging. The inactivity of the mOrange protein in acidic pH will decrease FRET efficiency making the emission green dominated by the UCNPs. In basic pH, the emission will be relatively orange. This is the first demonstration of ratiometric and self-ratiometric demonstration of intracellular pH imaging by the UCNPs. Next, we show a smart multifunctional nanoformulation of the UCNPs (NaGdF4: Yb, Er- 99mTc) using radioisotope labelling that shows potential for multimodal imaging using fluorescence, CT, and SPECT modalities. Intricate chemistry to engineer the UCNPs resulted in stabilizing the nanoformulation in physiological and aqueous environments with reproducible signal acquisition. This work gathers the expertise of physicists, chemists, and biologists in an interdisciplinary platform.

Original languageEnglish
Title of host publicationFuture Trends and Challenges of Molecular Imaging and AI Innovation - Proceedings of FASMI 2020
EditorsKang-Ping Lin, Ren-Shyan Liu, Bang-Hung Yang
PublisherSpringer Science and Business Media Deutschland GmbH
Number of pages8
ISBN (Print)9783030927851
StatePublished - 2022
EventInternational conference of Federation of Asian Societies for Molecular Imaging, FASMI 2020 - Taipei, Taiwan
Duration: 20 Nov 202022 Nov 2020

Publication series

NameSpringer Proceedings in Physics
ISSN (Print)0930-8989
ISSN (Electronic)1867-4941


ConferenceInternational conference of Federation of Asian Societies for Molecular Imaging, FASMI 2020


  • Bioimaging
  • Biosensing
  • FRET
  • pH sensing
  • Upconversion nanoparticles


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