A luminescent poly(amidoamine)-iridium complex as a new singlet-oxygen sensitizer for photodynamic therapy

Daniela Maggioni, Marco Galli, Laura D'Alfonso, Donato Inverso, Maria Vittoria Dozzi, Laura Sironi, Matteo Iannacone, Maddalena Collini, Paolo Ferruti, Elisabetta Ranucci, Giuseppe D'Alfonso

Research output: Contribution to journalArticle

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Abstract

A polymer complex (1P) was synthesized by binding bis(cyclometalated) Ir(ppy)2 + fragments (ppy = 2-phenylpyridyl) to phenanthroline (phen) pendants of a poly(amidoamine) copolymer (PhenISA, in which the phen pendants involved 6% of the repeating units). The corresponding molecular complex [Ir(ppy)2(bap)]+ (1M, bap = 4-(butyl-4-amino)-1,10-phenanthroline) was also prepared for comparison. In water solution 1P gives nanoaggregates with a hydrodynamic diameter of 30 nm in which the lipophilic metal centers are presumed to be segregated within polymer tasks to reduce their interaction with water. Such confinement, combined with the dilution of triplet emitters along the polymer chains, led to 1P having a photoluminescence quantum yield greater than that of 1M (0.061 vs 0.034, respectively, in an aerated water solution) with a longer lifetime of the 3MLCT excited states and a blue-shifted emission (595 nm vs 604 nm, respectively). NMR data supported segregation of the metal centers. Photoreaction of O2 with 1,5-dihydroxynaphthalene showed that 1P is able to sensitize 1O2 generation but with half the quantum yield of 1M. Cellular uptake experiments showed that both 1M and 1P are efficient cell staining agents endowed with two-photon excitation (TPE) imaging capability. TPE microscopy at 840 nm indicated that both complexes penetrate the cellular membrane of HeLa cells, localizing in the perinuclear region. Cellular photodynamic therapy tests showed that both 1M and 1P are able to induce cell apoptosis upon exposure to Xe lamp irradiation. The fraction of apoptotic cells for 1M was higher than that for 1P (74 and 38%, respectively) 6 h after being irradiated for 5 min, but cells incubated with 1P showed much lower levels of necrosis as well as lower toxicity in the absence of irradiation. More generally, the results indicate that cell damage induced by 1M was avoided by binding the iridium sensitizers to the poly(amidoamine).

Original languageEnglish
Pages (from-to)544-553
Number of pages10
JournalInorganic Chemistry
Volume54
Issue number2
DOIs
Publication statusPublished - Jan 20 2015

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Iridium
Singlet Oxygen
Photodynamic therapy
Photochemotherapy
iridium
therapy
Polymers
Phenanthrolines
Quantum yield
Water
oxygen
Photons
Metals
cells
Cells
Irradiation
polymers
water
excitation
Electric lamps

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry
  • Medicine(all)

Cite this

Maggioni, D., Galli, M., D'Alfonso, L., Inverso, D., Dozzi, M. V., Sironi, L., ... D'Alfonso, G. (2015). A luminescent poly(amidoamine)-iridium complex as a new singlet-oxygen sensitizer for photodynamic therapy. Inorganic Chemistry, 54(2), 544-553. https://doi.org/10.1021/ic502378z

A luminescent poly(amidoamine)-iridium complex as a new singlet-oxygen sensitizer for photodynamic therapy. / Maggioni, Daniela; Galli, Marco; D'Alfonso, Laura; Inverso, Donato; Dozzi, Maria Vittoria; Sironi, Laura; Iannacone, Matteo; Collini, Maddalena; Ferruti, Paolo; Ranucci, Elisabetta; D'Alfonso, Giuseppe.

In: Inorganic Chemistry, Vol. 54, No. 2, 20.01.2015, p. 544-553.

Research output: Contribution to journalArticle

Maggioni, D, Galli, M, D'Alfonso, L, Inverso, D, Dozzi, MV, Sironi, L, Iannacone, M, Collini, M, Ferruti, P, Ranucci, E & D'Alfonso, G 2015, 'A luminescent poly(amidoamine)-iridium complex as a new singlet-oxygen sensitizer for photodynamic therapy', Inorganic Chemistry, vol. 54, no. 2, pp. 544-553. https://doi.org/10.1021/ic502378z
Maggioni, Daniela ; Galli, Marco ; D'Alfonso, Laura ; Inverso, Donato ; Dozzi, Maria Vittoria ; Sironi, Laura ; Iannacone, Matteo ; Collini, Maddalena ; Ferruti, Paolo ; Ranucci, Elisabetta ; D'Alfonso, Giuseppe. / A luminescent poly(amidoamine)-iridium complex as a new singlet-oxygen sensitizer for photodynamic therapy. In: Inorganic Chemistry. 2015 ; Vol. 54, No. 2. pp. 544-553.
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