Modulating photochemical reactions in Langmuir monolayers of Escherichia coli lipid extract with the binding mechanisms of eosin decyl ester and toluidine blue-O photosensitizers

Author(s)

Moreira, Lucas G. ^[1] ; Almeida Jr, Alexandre M. ; Nield, Tyler ^{[2, 3]} ; Camacho, Sabrina A. ^{[4, 2]} ; Aoki, Pedro H. B. ^[2]

Affiliation

^[1] Sao Paulo State Univ, Sch Sci Humanities & Languages, UNESP, BR-19806900 Assis, SP - Brazil

^[2] Almeida Jr, Jr., Alexandre M., Sao Paulo State Univ, Sch Sci Humanities & Languages, UNESP, BR-19806900 Assis, SP - Brazil

^[3] Univ Victoria, Fac Engn, Victoria, BC V8P 5C2 - Canada

^[4] Univ Sao Paulo, Sao Carlos Inst Phys, IFSC, BR-13566590 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY; v. 218, MAY 2021.
• Web of Science Citations: 0

Abstract

Photodynamic damage to the cell envelope can inactivate microorganisms and may be applied to combat super-resistance phenomenon, empowered by the indiscriminate use of antibiotics. Efficiency in microbial inactivation is dependent on the incorporation of photosensitizers (PS) into the bacterial membranes to trigger oxidation reactions under illumination. Herein, Langmuir monolayers of Escherichia coli lipid extract were built to determine the binding mechanisms and oxidation outcomes induced by eosin decyl ester (EosDEC) and toluidine blue-O (TBO) PSs. Surface-pressure isotherms of the E. coli monolayers were expanded upon EosDEC and TBO, suggesting incorporation of both PSs. Fourier-transform infrared spectroscopy (FTIR) of Langmuir-Schaefer (LS) films reveled that the EosDEC and TBO binding mechanisms are dominated by electrostatic interactions with the anionic polar groups, with limited penetration into the chains. Light-irradiation reduced the relative area of E. coli monolayer on TBO, indicating an increased loss of material to the subphase owing to the chain cleavage, generated by contact-dependent reactions with excited states of TBO. In contrast, the increased relative area of E. coli monolayers containing EosDEC suggests lipid hydroperoxidation, which is PS contact-independent. Even considering a small chain penetration, the saturated EosDEC may have partitioned towards saturated reach domains, avoiding direct contact with membrane unsaturations. (AU)

• FAPESP's process: 20/15854-9 - Modulating photochemical reactions in Escherichia coli lipid monolayers with the binding mechanisms of eosin decyl ester and toluidine blue-O photosensitizers
• Grantee: Lucas Gontijo Moreira
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 18/16713-0 - Photodynamic therapy: from molecular effects in model systems toward photodynamic efficiency in cell culture
• Grantee: Pedro Henrique Benites Aoki
• Support Opportunities: Regular Research Grants
• FAPESP's process: 18/22214-6 - Towards a convergence of technologies: from sensing and biosensing to information visualization and machine learning for data analysis in clinical diagnosis
• Grantee: Osvaldo Novais de Oliveira Junior
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/14692-5 - Photothermal therapy mediated by gold nanoparticles: from model systems of biomembranes toward in vitro culture of tumor cells
• Grantee: Sabrina Aléssio Camacho
• Support Opportunities: Scholarships in Brazil - Post-Doctoral