title: Singlet oxygen in antimicrobial photodynamic therapy: photosensitizer-dependent production and decay in E. coli.
abstract: Several families of photosensitizers are currently being scrutinized for antimicrobial photodynamic therapy applications. Differences in physical and photochemical properties can lead to different localization patterns as well as differences in singlet oxygen production and decay when the photosensitizers are taken up by bacterial cells. We have examined the production and fate of singlet oxygen in Escherichia coli upon photosensitization with three structurally-different cationic photosensitizers, namely New Methylene Blue N (NMB), a member of the phenothiazine family, ACS268, a hydrophobic porphyrin with a single cationic alkyl chain, and zinc(II)-tetramethyltetrapyridinoporphyrazinium salt, a phthalocyanine-like photosensitizer with four positive charges on the macrocycle core. The kinetics of singlet oxygen production and decay indicate different localization for the three photosensitizers, whereby NMB appears to localize in an aqueous-like microenvironment, whereas ACS268 localizes in an oxygen-shielded site, highly reactive towards singlet oxygen. The tetracationic zinc(II) tetrapyridinoporphyrazine is extensively aggregated in the bacteria and fails to produce any detectable singlet oxygen.
authors: Grup d'Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, Barcelona E-08017, Spain.
authors: Xavier
authors: X
authors: Ragàs
authors: Xin
authors: X
authors: He
authors: Montserrat
authors: M
authors: Agut
authors: Mónica
authors: M
authors: Roxo-Rosa
authors: António Rocha
authors: AR
authors: Gonsalves
authors: Arménio C
authors: AC
authors: Serra
authors: Santi
authors: S
authors: Nonell
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects; D007211:Indoles / Q000737:chemistry; D054833:Isoindoles; D007700:Kinetics; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry* / Q000378:metabolism; D011166:Porphyrins / Q000737:chemistry; D026082:Singlet Oxygen / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000890:Anti-Infective Agents; D007211:Indoles; D054833:Isoindoles; D017319:Photosensitizing Agents; D011166:Porphyrins; D026082:Singlet Oxygen; C013647:phthalocyanine