Detection of singlet oxygen by EPR: the instability of the nitroxyl radicals

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dc.creatorHenrique Fernandes Vieira Victoria
dc.creatorDaniele Cristina Ferreira
dc.creatorJose Balena Gabriel Filho
dc.creatorDayse Carvalho da Silva Martins
dc.creatorMauricio Veloso Brant Pinheiro
dc.creatorGustavo de Almeida Magalhães Sáfar
dc.creatorKlaus Wilhelm Heinrich Krambrock
dc.date.accessioned2025-02-24T17:45:48Z
dc.date.accessioned2025-09-08T23:55:14Z
dc.date.available2025-02-24T17:45:48Z
dc.date.issued2022
dc.description.sponsorshipCNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
dc.description.sponsorshipFAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
dc.description.sponsorshipCAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
dc.description.sponsorshipFINEP - Financiadora de Estudos e Projetos, Financiadora de Estudos e Projetos
dc.identifier.doihttps://doi.org/10.1016/j.freeradbiomed.2021.12.303
dc.identifier.issn0891-5849
dc.identifier.urihttps://hdl.handle.net/1843/80350
dc.languageeng
dc.publisherUniversidade Federal de Minas Gerais
dc.relation.ispartofFree Radical Biology and Medicine
dc.rightsAcesso Restrito
dc.subjectRessonância paramagnética eletrônica
dc.subjectOxigênio
dc.subjectOxigenio
dc.subjectPorfirina e compostos de porfirina
dc.subject.otherHydroxy-TEMP
dc.subject.otherSinglet oxygen
dc.subject.otherRedox probe
dc.subject.otherNitroxyl radical
dc.subject.otherOxidation
dc.subject.otherPorphyrins
dc.subject.otherDegradation
dc.subject.otherSpin trapping
dc.subject.otherPhotodynamic therapy (PDT)
dc.titleDetection of singlet oxygen by EPR: the instability of the nitroxyl radicals
dc.typeArtigo de periódico
local.citation.epage152
local.citation.spage143
local.citation.volume180
local.description.resumoThe use of spin traps and redox probes coupled with electron paramagnetic resonance (EPR) is a method frequently applied in the evaluation of the efficiency of photosensitizers and photocatalysts in phototherapeutic and photocatalytic processes that involve reactive oxygen species. In this way, the method helps to clarify the mechanism behind photo-induced reactions. Hydroxy-TEMP is a very specific redox probe for selectively identifying and quantifying singlet oxygen (1O2). In this work, the kinetics of radical generated by the oxidation products of the Hydroxy-TEMP redox probe was analyzed from EPR spectra in aqueous solutions of several water-soluble porphyrins ([H2T4MPyP](OTs)4, Na4[H2T4SPP], [H2T2MPyP](OTs)4, [ZnT4MyPyP](OTs)4, [MnT4MyPyP](OTs)5, H2T4CPP, and [H2T4TriMAPP](OTs)4) under white light illumination. Different factors such as the concentration of the redox probe, pH of the medium, and photostability of the porphyrins were evaluated. A systematic study was carried out to reveal the factors associated with stable radical degradation (TEMPOL) by illumination in the visible spectral region in systems containing photosensitizer (porphyrin) and redox probe (Hydroxy-TEMP). With the aid of EPR and gas chromatography coupled with mass spectroscopy (GC-MS) techniques, the mechanism of the radical degradation and the photobleaching of porphyrins were investigated. After successive interactions with the porphyrin in its excited state, in alkaline aqueous solution (pH > 10), the free radical TEMPOL is transformed into TEMPONE until the final diamagnetic product Phorone. A protocol was elaborated to identify and quantify the generation of 1O2 by Hydroxy-TEMP reliably, to avoid possible errors in the interpretation of efficiency of photosensitizers.
local.identifier.orcidhttps://orcid.org/0000-0002-4846-2189
local.identifier.orcidhttps://orcid.org/0000-0001-9523-1298
local.identifier.orcidhttps://orcid.org/0000-0003-1641-6476
local.identifier.orcidhttps://orcid.org/0000-0001-6230-2168
local.identifier.orcidhttps://orcid.org/0000-0001-5722-6260
local.identifier.orcidhttps://orcid.org/0000-0003-1354-3138
local.identifier.orcidhttps://orcid.org/0000-0002-7562-0285
local.publisher.countryBrasil
local.publisher.departmentICX - DEPARTAMENTO DE FÍSICA
local.publisher.departmentICX - DEPARTAMENTO DE QUÍMICA
local.publisher.initialsUFMG
local.url.externahttps://www.sciencedirect.com/science/article/pii/S0891584921011552?via%3Dihub

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