Volume 64, Issue 28 e202506396
Research Article

Mechanosensitive Conjugated Oligoelectrolytes for Visualizing Temporal Changes in Live Cells

Dr. Ji-Yu Zhu

Dr. Ji-Yu Zhu

Department of Chemistry, National University of Singapore, Singapore, 117543 Singapore

Institute for Digital Molecular Analytics and Science, Nanyang Technological University, Singapore, 636921 Singapore

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Dr. Samuel J. W. Chan

Dr. Samuel J. W. Chan

Department of Chemistry, National University of Singapore, Singapore, 117543 Singapore

Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544 Singapore

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Hongyue Cui

Hongyue Cui

Mechanobiology Institute, National University of Singapore, Singapore, 117411 Singapore

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Dr. Alexander A. Mikhalovsky

Dr. Alexander A. Mikhalovsky

Department of Chemistry and Biochemistry, Center for Polymers and Organic Solids, University of California Santa Barbara, Santa Barbara, California, 93106 USA

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Dr. Fernando L. Garcia

Dr. Fernando L. Garcia

Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544 Singapore

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Brandon Yeow Wee Goh

Brandon Yeow Wee Goh

Mechanobiology Institute, National University of Singapore, Singapore, 117411 Singapore

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Dr. Wilson Wee Mia Soh

Dr. Wilson Wee Mia Soh

Department of Chemistry, National University of Singapore, Singapore, 117543 Singapore

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Dr. Alex S. Moreland

Dr. Alex S. Moreland

Department of Chemistry and Biochemistry, Center for Polymers and Organic Solids, University of California Santa Barbara, Santa Barbara, California, 93106 USA

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Dr. Jakkarin Limwongyut

Dr. Jakkarin Limwongyut

Department of Chemistry, National University of Singapore, Singapore, 117543 Singapore

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Dr. Sukanya Shyamasundar

Dr. Sukanya Shyamasundar

Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117594 Singapore

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Dr. Ya Jun Wu

Dr. Ya Jun Wu

Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117594 Singapore

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Prof. Fengyi Liang

Prof. Fengyi Liang

Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117594 Singapore

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Prof. Rong Li

Prof. Rong Li

Mechanobiology Institute, National University of Singapore, Singapore, 117411 Singapore

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Prof. Guillermo C. Bazan

Corresponding Author

Prof. Guillermo C. Bazan

Department of Chemistry, National University of Singapore, Singapore, 117543 Singapore

Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544 Singapore

Institute for Digital Molecular Analytics and Science, Nanyang Technological University, Singapore, 636921 Singapore

Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117585 Singapore

E-mail: [email protected]

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First published: 05 May 2025

Graphical Abstract

Mechanosensitive conjugated oligoelectrolytes (COEs) with integrated twistable bonds enable real-time imaging of membrane tension in lipid bilayers. Using fluorescence lifetime analysis, COE-BY probes reveal vesicle rigidity changes during endocytosis, providing insights into membrane mechanics at the subcellular level.

Abstract

Membrane-intercalating conjugated oligoelectrolytes (COEs) are lipid-bilayer-spanning molecules that serve as fluorescent dyes for bioimaging. However, COE emission has thus far only been capable of visualizing dye location and their preferential accumulation in different membrane-bound intracellular compartments. Herein, we report the first example of environmentally sensitive COEs for visualizing temporal changes in live cells, providing information on the physical properties of intracellular lipid bilayer membranes. The new COE-BY series is designed around a BODIPY central unit with a membrane-spanning topology and six cationic pendant groups ensuring solubility in aqueous media. These reporters feature high two-photon absorption cross section, NIR-II excitation capabilities under multiphoton excitation, and high dye brightness; all highly desirable photophysical features for bioimaging. The emission lifetime of the probes was sensitive to changes to both the lipid composition of model vesicle systems and membrane tension within cells, induced by either mechanical or osmotic stress. Using two-photon fluorescence lifetime imaging microscopy, it is possible to use the most efficient emitter, namely, COE-BYPhOC4, to image changes in the mechanical properties of intracellular membranes. We show that these COEs remain stably vesicle-bound within the endolysosomal pathway over extended periods, allowing for long-term monitoring of the associated biophysical changes of these vesicles over time.

Conflict of Interests

G.C.B. and J.-Y.Z. have filed for a provisional patent as employees of the National University of Singapore. The other authors declare no conflict of interest.

Data Availability Statement

The data that support the findings of this study are available in Supporting Information of this article.

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.