Issue 36, 2015

New imaging reagents for lipid dense regions in live cells and the nucleus in fixed MCF-7 cells

Abstract

Two new uracil (U) and 5-flurouracil (5-FU) labeled ruthenium(II)-polypyridyl based cellular imaging reagents are reported. Confocal laser scanning microscopic images with live and paraformaldehyde (PFA) fixed MCF-7 cells are examined using these two low-cytotoxic reagents. Experimental results show that these two complexes, appropriately functionalized with U (1) and 5-FU (2), have specific affinity for the lipid dense regions like the endoplasmic reticulum, cell membrane, and cytoplasmic vacuoles in live MCF-7 cells, and dye internalization in these regions happened following an endocytosis pathway. Interestingly, these two complexes are found to be localized in the nucleus of the PFA fixed cells. For fixed cells, presumably the lipid layer disruption helped in the explicit localization of the complexes 1 and 2 in the cell nucleus through specific interaction with cellular DNA. Poor and non-specific internalization of an analogous model complex 3, without having a U or 5-FU moiety, reveals the definite influence of U or 5-FU as well as the role of lipophilicity of the respective complex 1 and 2 in the cellular internalization process. Apart from these, a large Stokes shift (∼160 nm) and an appreciably long lived 3MLCT excited state (∼320 ns) in aq. buffer medium (pH 7.4) are other key features for complexes 1 and 2. Unlike the common nuclear DNA staining reagents like DAPI, these low-cytotoxic reagents are found to be highly stable towards photo-bleaching upon irradiation with 455 nm at the MLCT band for these complexes.

Graphical abstract: New imaging reagents for lipid dense regions in live cells and the nucleus in fixed MCF-7 cells

Supplementary files

Article information

Article type
Paper
Submitted
02 heinä 2015
Accepted
03 elo 2015
First published
04 elo 2015

J. Mater. Chem. B, 2015,3, 7177-7185

Author version available

New imaging reagents for lipid dense regions in live cells and the nucleus in fixed MCF-7 cells

V. Ramu, F. Ali, N. Taye, B. Garai, A. Alam, S. Chattopadhyay and A. Das, J. Mater. Chem. B, 2015, 3, 7177 DOI: 10.1039/C5TB01309G

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