Jump to main content
Jump to site search


Bis[pyrrolyl Ru(ii)] triads: a new class of photosensitizers for metal–organic photodynamic therapy

Author affiliations

Abstract

A new family of ten dinuclear Ru(II) complexes based on the bis[pyrrolyl Ru(II)] triad scaffold, where two Ru(bpy)2 centers are separated by a variety of organic linkers, was prepared to evaluate the influence of the organic chromophore on the spectroscopic and in vitro photodynamic therapy (PDT) properties of the compounds. The bis[pyrrolyl Ru(II)] triads absorbed strongly throughout the visible region, with several members having molar extinction coefficients (ε) ≥ 104 at 600–620 nm and longer. Phosphorescence quantum yields (Φp) were generally less than 0.1% and in some cases undetectable. The singlet oxygen quantum yields (ΦΔ) ranged from 5% to 77% and generally correlated with their photocytotoxicities toward human leukemia (HL-60) cells regardless of the wavelength of light used. Dark cytotoxicities varied ten-fold, with EC50 values in the range of 10–100 μM and phototherapeutic indices (PIs) as large as 5400 and 260 with broadband visible (28 J cm−2, 7.8 mW cm−2) and 625 nm red (100 J cm−2, 42 mW cm−2) light, respectively. The bis[pyrrolyl Ru(II)] triad with a pyrenyl linker (5h) was especially potent, with an EC50 value of 1 nM and PI > 27 000 with visible light and subnanomolar activity with 625 nm light (100 J cm−2, 28 mW cm−2). The lead compound 5h was also tested in a tumor spheroid assay using the HL60 cell line and exhibited greater photocytotoxicity in this more resistant model (EC50 = 60 nM and PI > 1200 with 625 nm light) despite a lower dark cytotoxicity. The in vitro PDT effects of 5h extended to bacteria, where submicromolar EC50 values and PIs >300 against S. mutans and S. aureus were obtained with visible light. This activity was attenuated with 625 nm red light, but PIs were still near 50. The ligand-localized 3ππ* state contributed by the pyrenyl linker of 5h likely plays a key role in its phototoxic effects toward cancer cells and bacteria.

Graphical abstract: Bis[pyrrolyl Ru(ii)] triads: a new class of photosensitizers for metal–organic photodynamic therapy

Back to tab navigation

Supplementary files

Article information


Submitted
15 Aug 2020
Accepted
06 Oct 2020
First published
06 Oct 2020

This article is Open Access
All publication charges for this article have been paid for by the Royal Society of Chemistry

Chem. Sci., 2020, Advance Article
Article type
Edge Article

Bis[pyrrolyl Ru(II)] triads: a new class of photosensitizers for metal–organic photodynamic therapy

D. A. Smithen, S. Monro, M. Pinto, J. Roque, R. M. Diaz-Rodriguez, H. Yin, C. G. Cameron, A. Thompson and S. A. McFarland, Chem. Sci., 2020, Advance Article , DOI: 10.1039/D0SC04500D

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material and it is not used for commercial purposes.

Reproduced material should be attributed as follows:

  • For reproduction of material from NJC:
    [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
  • For reproduction of material from PCCP:
    [Original citation] - Published by the PCCP Owner Societies.
  • For reproduction of material from PPS:
    [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
  • For reproduction of material from all other RSC journals:
    [Original citation] - Published by The Royal Society of Chemistry.

Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.


Social activity

Search articles by author

Spotlight

Advertisements