title: The quest for biocompatible phthalocyanines for molecular imaging: Photophysics, relaxometry and cytotoxicity studies.
abstract: Water soluble phthalocyanines bearing either four PEG500 or four choline substituents in the macrocyclic structure, as well as their Zn(II) and Mn(III) complexes were synthesized. The metal-free and Zn(II) complexes present relatively high fluorescence quantum yields (up to 0.30), while the Mn(III) complexes show no fluorescence as a consequence of rapid non-radiative deactivation of the Mn(III) phthalocyanine excited states through low-lying metal based or charge-transfer states. The effect of DMSO on the aggregation of the phthalocyanines was studied. It was not possible to obtain the Mn(II) complexes by reduction of the corresponding Mn(III) complexes due to the presence of electron donating substituents at the periphery of the phthalocyanines. The (1)H NMRD plots of the PEG500 and choline substituted Mn(III)-phthalocyanine complexes are typical of self-aggregated Mn(III) systems with r1 relaxivities of 4.0 and 5.7mM(-1)s(-1) at 20MHz and 25°C. The Mn(III)-phthalocyanine-PEG4 complex shows no significant cytotoxicity to HeLa cell cultures after 2h of incubation up to 2mM concentration. After 24h of cell exposure to the compound, significant toxicity was observed for all the concentrations tested with IC50 of 1.105mM.
authors.affiliation: Department of Chemistry, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal; Coimbra Chemistry Centre, CQC, University of Coimbra, Coimbra, Portugal.
authors.forename: Sara M A
authors.initials: SM
authors.lastname: Pinto
authors.affiliation: Department of Chemistry, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal; Coimbra Chemistry Centre, CQC, University of Coimbra, Coimbra, Portugal.
authors.forename: Vanessa A
authors.initials: VA
authors.lastname: Tomé
authors.affiliation: Department of Chemistry, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal; Coimbra Chemistry Centre, CQC, University of Coimbra, Coimbra, Portugal. Electronic address: mcalvete@qui.uc.pt.
authors.forename: Mário J F
authors.initials: MJ
authors.lastname: Calvete
authors.affiliation: Department of Chemistry, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal; Coimbra Chemistry Centre, CQC, University of Coimbra, Coimbra, Portugal.
authors.forename: Mariette M
authors.initials: MM
authors.lastname: Pereira
authors.affiliation: Department of Chemistry, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal; Coimbra Chemistry Centre, CQC, University of Coimbra, Coimbra, Portugal.
authors.forename: Hugh D
authors.initials: HD
authors.lastname: Burrows
authors.affiliation: Department of Life Sciences, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal; Center of Neurosciences and Cell Biology, CNC, University of Coimbra, Coimbra, Portugal.
authors.forename: Ana M S
authors.initials: AM
authors.lastname: Cardoso
authors.affiliation: Centre de Biophysique Moléculaire, CNRS, UPR 4301, Université d'Orléans, Orléans, France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Pallier
authors.affiliation: Coimbra Chemistry Centre, CQC, University of Coimbra, Coimbra, Portugal; Department of Life Sciences, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal.
authors.forename: M Margarida
authors.initials: MM
authors.lastname: C A Castro
authors.affiliation: Centre de Biophysique Moléculaire, CNRS, UPR 4301, Université d'Orléans, Orléans, France.
authors.forename: Éva
authors.initials: É
authors.lastname: Tóth
authors.affiliation: Coimbra Chemistry Centre, CQC, University of Coimbra, Coimbra, Portugal; Department of Life Sciences, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal. Electronic address: geraldes@ci.uc.pt.
authors.forename: Carlos F G C
authors.initials: CF
authors.lastname: Geraldes
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D002794:Choline / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000633:toxicity; D006367:HeLa Cells; D006801:Humans; D007211:Indoles / Q000138:chemical synthesis* / Q000633:toxicity; D020128:Inhibitory Concentration 50; D054833:Isoindoles; D057054:Molecular Imaging; D011092:Polyethylene Glycols / Q000138:chemical synthesis* / Q000633:toxicity
chemical_list: D007211:Indoles; D054833:Isoindoles; D011092:Polyethylene Glycols; D002794:Choline; C013647:phthalocyanine
keywords: Biocompatible; Cytotoxicity; Metallophthalocyanines; Molecular imaging; Photophysics; Relaxivity