Design strategy for germanium-rhodamine based pH-activatable near-infrared fluorescence probes suitable for biological applications

Yuichiro Koide, Ryosuke Kojima, Kenjiro Hanaoka, Koji Numasawa, Toru Komatsu, Tetsuo Nagano, Hisataka Kobayashi, Yasuteru Urano

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Fluorescence probes that can detect pH are useful tools for biological research and clinical diagnosis. Here we report pH-activatable near-infrared fluorescence probes, based on hydroxymethyl germanium-rhodamine (HMGeR), that are suitable for a range of biological applications. The pKa, the ratio of the fluorescent form in an acidic environment, and the absorption/emission wavelengths can all be conveniently optimized. The most promising probe, 2-HM IGeR, offers significant advantages over currently available near-infrared pH probes, notably high quantum efficiency, appropriate pKa value for biological applications, and high photostability. Further, our molecular design strategy allows easy conjugation of the probes to biomolecules without loss of functionality. We illustrate the value of this strategy by developing probe-Herceptin® and probe-avidin conjugates to visualize pH change in cellular vesicles during endocytosis, and to visualize tumors in a mouse model, respectively. We believe 2-HM IGeR is currently among the best-in-class pH-activatable near-infrared probes for biological and medical research.

Original languageEnglish
Article number94
JournalCommunications Chemistry
Volume2
Issue number1
DOIs
Publication statusPublished - 2019 Dec 1
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry
  • Environmental Chemistry
  • Biochemistry

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