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Labeling phospholipid membranes with lipid mimetic luminescent metal complexes

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Version 2 2024-06-03, 20:27
Version 1 2018-08-24, 14:44
journal contribution
posted on 2024-06-03, 20:27 authored by A Mechler, BD Stringer, MSH Mubin, Egan DoevenEgan Doeven, NW Phillips, J Rudd-Schmidt, CF Hogan
Lipid-mimetic metallosurfactant based luminophores are promising candidates for labeling phospholipid membranes without altering their biophysical characteristics. The metallosurfactants studied exhibit high structural and physicochemical similarity to phospholipid molecules, designed to incorporate into the membrane structure without the need for covalent attachment to a lipid molecule. In this work, two lipid-mimetic phosphorescent metal complexes are described: [Ru(bpy)2(dn-bpy)]2 + and [Ir(ppy) 2(dn-bpy)]+ where bpy is 2,2′-bipyridine, dn-bpy is 4,4′-dinonyl-2,2′-bipyridine and ppy is 2-phenylpyridine. Apart from being lipid-mimetic in size, shape and physical properties, both complexes exhibit intense photoluminescence and enhanced photostability compared with conventional organic fluorophores, allowing for prolonged observation. Moreover, the large Stokes shift and long luminescence lifetime associated with these complexes make them more suitable for spectroscopic studies. The complexes are easily incorporated into dimyristoil-phosphatidyl-choline (DMPC) liposomes by mixing in the organic solvent phase. DLS reveals the labeled membranes form liposomes of similar size to that of neat DMPC membrane. Synchrotron Small-Angle X-ray Scattering (SAXS) measurements confirmed that up to 5% of either complex could be incorporated into DMPC membranes without producing any structural changes in the membrane. Fluorescence microscopy reveals that 0.5% label content is sufficient for imaging. Atomic Force Microscopic imaging confirms that liposomes of the labeled bilayers on a mica surface can fuse into a flat lamellar membrane that is morphologically identical to neat lipid membranes. These results demonstrate the potential of such lipid-mimetic luminescent metal complexes as a new class of labels for imaging lipid membranes. © 2014 Elsevier B.V.

History

Journal

Biochimica et biophysica acta - biomembranes

Volume

1838

Pagination

2939-2946

Location

Amsterdam, The Netherlands

ISSN

0005-2736

eISSN

1879-2642

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2014, Elsevier

Issue

11

Publisher

Elsevier

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