NIR-Absorbing RuII Complexes Containing α-Oligothiophenes for Applications in Photodynamic Therapy.
Chembiochem
; 21(24): 3594-3607, 2020 12 11.
Article
em En
| MEDLINE
| ID: mdl-32761725
ABSTRACT
The design of near-infrared (NIR)-active photosensitizers (PSs) for light-based cancer treatments such as photodynamic therapy (PDT) has been a challenge. While several NIR-RuII scaffolds have been reported, this approach has not been proven in cells. This is the first report of NIR-RuII PSs that are phototoxic to cancer cells, including highly pigmented B16F10 melanoma cells. The PS family incorporated a bis(1,8-naphthyridine)-based ligand (tpbn), a bidentate thiophene-based ligand (nT; n=0-4), and a monodentate 4-picoline ligand (4-pic). All compounds absorbed light >800â
nm with maxima near 730â
nm. Transient absorption (TA) measurements indicated that n=4 thiophene rings (4T) positioned the PDT-active triplet intraligand charge transfer (3 ILCT) excited state in energetic proximity to the lowest-lying triplet metal-to-ligand charge transfer (3 MLCT). 4T had low-micromolar phototoxicity with PIvis and PI733nm values as large as 90 and 12, respectively. Spectroscopic studies suggested that the longer-lived (τTA =3-6â
µs) 3 ILCT state was accessible from the 3 MLCT state, but energetically uphill in the overall photophysics. The study highlights that phototoxic effects can be achieved with NIR-absorbing RuII PSs as long as the reactive 3 ILCT states are energetically accessible from the low-energy 3 MLCT states. It also demonstrates that tissue-penetrating NIR light can be used to activate the PSs in highly pigmented cells where melanin attenuates shorter wavelengths of light.
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MEDLINE
Assunto principal:
Fotoquimioterapia
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Rutênio
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Tiofenos
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Fármacos Fotossensibilizantes
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Complexos de Coordenação
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Antineoplásicos
Limite:
Animals
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Female
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Humans
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Male
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article