Live-Cell Raman Imaging Elucidates Intracellular Distribution of Macrocyclic Peptides Designed as HIV Protease
Yasunori Nawa1, Tetsuya Miyano2, Kazuki Bando1,3
1AIST-Osaka University Advanced Photonics and Biosensing Open Innovation Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Chemical & Biomedical Imaging
|February 27, 2026
Summary
Live-cell Raman imaging detected intracellular macrocyclic peptides, challenging traditional permeability tests. This advanced technique offers a more detailed evaluation for drug design, improving therapeutic potential.
Area of Science:
- Biochemistry
- Chemical Biology
- Pharmacology
Background:
- Macrocyclic peptides show therapeutic promise but face challenges with low cell membrane permeability.
- Limited access to intracellular targets hinders the efficacy of macrocyclic peptide therapeutics.
Purpose of the Study:
- To apply live-cell Raman imaging for detecting intracellular macrocyclic peptides.
- To evaluate the effectiveness of Raman imaging as a tool for assessing macrocyclic peptide permeability.
- To investigate the limitations of traditional penetration tests in macrocyclic peptide drug design.
Main Methods:
- Alkyne-tagged macrocyclic peptides (HIV protease inhibitors) were synthesized.
- Membrane permeability was assessed using traditional penetration tests.
- Live-cell Raman imaging (2D and 3D) was employed to detect intracellular peptides.
Main Results:
- Alkyne-tagged macrocyclic peptides were detected intracellularly using Raman imaging, even when exhibiting no permeability in traditional tests.
- The alkyne signal was not observed in cells treated with peptides that showed penetration in the penetration test.
- Observed results align with pharmacological activities, suggesting limitations in traditional penetration assays.
Conclusions:
- Traditional penetration tests may be insufficient for evaluating macrocyclic peptide drug design.
- Live-cell Raman imaging provides a more comprehensive assessment of macrocyclic peptide permeability.
- Combining Raman imaging with traditional methods enhances the evaluation of intracellular drug delivery.
