Novel cyclometalated iridium (III) complexes as antibacterial agents for photodynamic inactivation

Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) frequently cause chronic skin and soft tissue infections and device-related infections. These bacteria colonize human skin and can survive for long periods within biofilms, on indwelling medical devices, high touch surfaces and equipme...

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Autores: Fallon, Muireann, Lalrempuia, Ralte, Tabrizi, Leila, Brandon, Michael P., McGarry, Ross, Cullen, Aoibhín, Fernández-Álvarez, Francisco J., Pryce, Mary T., Fitzgerald-Hughes, Deirdre
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2025
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/391555
Acceso en línea:http://hdl.handle.net/10261/391555
Access Level:acceso abierto
Palabra clave:Cyclometalated iridium(III) complex
Antimicrobial photodynamic therapy
Photosensitizer
Singlet oxygen
Photo-sterilisation
Transient spectroscopy
Electrochemistry
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oai_identifier_str oai:digital.csic.es:10261/391555
network_acronym_str ES
network_name_str España
repository_id_str
dc.title.none.fl_str_mv Novel cyclometalated iridium (III) complexes as antibacterial agents for photodynamic inactivation
title Novel cyclometalated iridium (III) complexes as antibacterial agents for photodynamic inactivation
spellingShingle Novel cyclometalated iridium (III) complexes as antibacterial agents for photodynamic inactivation
Fallon, Muireann
Cyclometalated iridium(III) complex
Antimicrobial photodynamic therapy
Photosensitizer
Singlet oxygen
Photo-sterilisation
Transient spectroscopy
Electrochemistry
title_short Novel cyclometalated iridium (III) complexes as antibacterial agents for photodynamic inactivation
title_full Novel cyclometalated iridium (III) complexes as antibacterial agents for photodynamic inactivation
title_fullStr Novel cyclometalated iridium (III) complexes as antibacterial agents for photodynamic inactivation
title_full_unstemmed Novel cyclometalated iridium (III) complexes as antibacterial agents for photodynamic inactivation
title_sort Novel cyclometalated iridium (III) complexes as antibacterial agents for photodynamic inactivation
dc.creator.none.fl_str_mv Fallon, Muireann
Lalrempuia, Ralte
Tabrizi, Leila
Brandon, Michael P.
McGarry, Ross
Cullen, Aoibhín
Fernández-Álvarez, Francisco J.
Pryce, Mary T.
Fitzgerald-Hughes, Deirdre
author Fallon, Muireann
author_facet Fallon, Muireann
Lalrempuia, Ralte
Tabrizi, Leila
Brandon, Michael P.
McGarry, Ross
Cullen, Aoibhín
Fernández-Álvarez, Francisco J.
Pryce, Mary T.
Fitzgerald-Hughes, Deirdre
author_role author
author2 Lalrempuia, Ralte
Tabrizi, Leila
Brandon, Michael P.
McGarry, Ross
Cullen, Aoibhín
Fernández-Álvarez, Francisco J.
Pryce, Mary T.
Fitzgerald-Hughes, Deirdre
author2_role author
author
author
author
author
author
author
author
dc.contributor.none.fl_str_mv Department of Further and Higher Education, Research, Innovation and Science (Ireland)
European Commission
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Cyclometalated iridium(III) complex
Antimicrobial photodynamic therapy
Photosensitizer
Singlet oxygen
Photo-sterilisation
Transient spectroscopy
Electrochemistry
topic Cyclometalated iridium(III) complex
Antimicrobial photodynamic therapy
Photosensitizer
Singlet oxygen
Photo-sterilisation
Transient spectroscopy
Electrochemistry
description Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) frequently cause chronic skin and soft tissue infections and device-related infections. These bacteria colonize human skin and can survive for long periods within biofilms, on indwelling medical devices, high touch surfaces and equipment in the healthcare setting, which are reservoirs for further transmission to patients. Photodynamic therapy may offer an alternative to antibiotics in the management of infections or photodynamic disinfection may limit transmission of specific pathogens in the healthcare setting. Two novel cyclometalated iridium (III) complexes [Ir(ppy)2L](PF6) (ppy: phenyl pyridine, L = 6-((2,6-diisopropylphenyl)amino)-5,6-dihydro-1,10-phenanthrolin-5-ol (Ir1) and L = N-(2,6-diisopropylphenyl)-1,10-phenanthrolin-5-amine (Ir2)) were synthesized and evaluated for their antimicrobial properties when activated by light (370 nm). Iridium complexes (Ir1 and Ir2) led to potent inactivation of planktonic Staphylococcus aureus at 5 µM (almost 5 log10 reduction in colony forming units (CFU)/mL) after light exposure (p ≤ 0.01 for dark vs light). Dark toxicity was < 1 log10. Under the same conditions, Escherichia coli killing was < 1 log10. Anti-staphylococcal activity was concentration-dependant over the range 0.1 µM − 5 µM (p ≤ 0.001, Ir1, p ≤ 0.01 Ir2). Anti-biofilm activity was observed against mature (72 h) biofilms of S. aureus including methicillin-resistant S. aureus (MRSA) biofilms but higher concentrations (50 μM) were required. Treatment with Ir1 or Ir2 resulted in removal of 20 – 32 % of biofilm biomass as measured by crystal violet staining and 24 – 73 % reduction in the metabolic activity of cells within the biofilm, using resazurin reduction assays. Cytotoxicity to cultured human keratinocytes was minimal at antimicrobial concentrations but increased with higher concentrations, for Ir1 but not Ir2 (Ir1 p ≤ 0.01, 5 Vs 50 μM). The quantum yield for singlet oxygen (1O2) emission was measured as 0.16 and 0.30 for Ir1 and Ir2 respectively. Ground and excited state UV–Vis absorption, steady-state and time-resolved studies together with cyclic voltammetry are also presented. In summary, the potent and rapid antimicrobial activity of these cyclometalated iridium (III) complexes against S. aureus and MRSA, which included biofilm eradication, highlight their potential in the management or prevention of device-associated infections or healthcare transmission involving these pathogens.
publishDate 2025
dc.date.none.fl_str_mv 2025
2025
2025
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Publisher's version
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/391555
url http://hdl.handle.net/10261/391555
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv #PLACEHOLDER_PARENT_METADATA_VALUE#
info:eu-repo/grantAgreement/EC/H2020/799778
The underlying dataset has been published as supplementary material of the article in the publisher platform at DOI 10.1016/j.jphotochem.2024.116218
https://doi.org/10.1016/j.jphotochem.2024.116218

dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Elsevier
publisher.none.fl_str_mv Elsevier
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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spelling Novel cyclometalated iridium (III) complexes as antibacterial agents for photodynamic inactivationFallon, MuireannLalrempuia, RalteTabrizi, LeilaBrandon, Michael P.McGarry, RossCullen, AoibhínFernández-Álvarez, Francisco J.Pryce, Mary T.Fitzgerald-Hughes, DeirdreCyclometalated iridium(III) complexAntimicrobial photodynamic therapyPhotosensitizerSinglet oxygenPhoto-sterilisationTransient spectroscopyElectrochemistryStaphylococcus aureus and methicillin-resistant S. aureus (MRSA) frequently cause chronic skin and soft tissue infections and device-related infections. These bacteria colonize human skin and can survive for long periods within biofilms, on indwelling medical devices, high touch surfaces and equipment in the healthcare setting, which are reservoirs for further transmission to patients. Photodynamic therapy may offer an alternative to antibiotics in the management of infections or photodynamic disinfection may limit transmission of specific pathogens in the healthcare setting. Two novel cyclometalated iridium (III) complexes [Ir(ppy)2L](PF6) (ppy: phenyl pyridine, L = 6-((2,6-diisopropylphenyl)amino)-5,6-dihydro-1,10-phenanthrolin-5-ol (Ir1) and L = N-(2,6-diisopropylphenyl)-1,10-phenanthrolin-5-amine (Ir2)) were synthesized and evaluated for their antimicrobial properties when activated by light (370 nm). Iridium complexes (Ir1 and Ir2) led to potent inactivation of planktonic Staphylococcus aureus at 5 µM (almost 5 log10 reduction in colony forming units (CFU)/mL) after light exposure (p ≤ 0.01 for dark vs light). Dark toxicity was < 1 log10. Under the same conditions, Escherichia coli killing was < 1 log10. Anti-staphylococcal activity was concentration-dependant over the range 0.1 µM − 5 µM (p ≤ 0.001, Ir1, p ≤ 0.01 Ir2). Anti-biofilm activity was observed against mature (72 h) biofilms of S. aureus including methicillin-resistant S. aureus (MRSA) biofilms but higher concentrations (50 μM) were required. Treatment with Ir1 or Ir2 resulted in removal of 20 – 32 % of biofilm biomass as measured by crystal violet staining and 24 – 73 % reduction in the metabolic activity of cells within the biofilm, using resazurin reduction assays. Cytotoxicity to cultured human keratinocytes was minimal at antimicrobial concentrations but increased with higher concentrations, for Ir1 but not Ir2 (Ir1 p ≤ 0.01, 5 Vs 50 μM). The quantum yield for singlet oxygen (1O2) emission was measured as 0.16 and 0.30 for Ir1 and Ir2 respectively. Ground and excited state UV–Vis absorption, steady-state and time-resolved studies together with cyclic voltammetry are also presented. In summary, the potent and rapid antimicrobial activity of these cyclometalated iridium (III) complexes against S. aureus and MRSA, which included biofilm eradication, highlight their potential in the management or prevention of device-associated infections or healthcare transmission involving these pathogens.Funding for this project is gratefully acknowledged from Research Ireland (RI) (19/FFP/6882, 19/FFP/6956), the European Commission, through a Marie Sklodowska − Curie Fellowship to RL (No. 799778) and the EU Commission Recovery and Resilience Facility under the Research Ireland, Healthy Environment for All, Challenge Grant Number 22/NCF/HE/11252.Peer reviewedElsevierDepartment of Further and Higher Education, Research, Innovation and Science (Ireland)European CommissionConsejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]202520252025info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionapplication/pdfhttp://hdl.handle.net/10261/391555reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Inglés#PLACEHOLDER_PARENT_METADATA_VALUE#info:eu-repo/grantAgreement/EC/H2020/799778The underlying dataset has been published as supplementary material of the article in the publisher platform at DOI 10.1016/j.jphotochem.2024.116218https://doi.org/10.1016/j.jphotochem.2024.116218Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/3915552026-05-22T06:33:51Z
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