Photoinactivation of Planktonic and Biofilm Forms of Escherichia coli through the Action of Cationic Zinc(II) Phthalocyanines

Journal Article · Fri Feb 22 00:00:00 EST 2019 · ChemPhotoChem

DOI:https://doi.org/10.1002/cptc.201900020· OSTI ID:1511867

Lourenço, Leandro M. O. ^[1]; Rocha, Deisy M. G. C. ^[2]; Ramos, Catarina I. V. ^[3]; Gomes, Maria C. ^[2]; Almeida, Adelaide ^[4]; Faustino, Maria A. F. ^[1]; Almeida Paz, Filipe A. ^[5]; Neves, Maria G. P. M. S. ^[1]; Cunha, Ângela ^[4]; Tomé, João P. C. ^[6]

---

1. QOPNA-LAQV-REQUINTE and Department of Chemistry University of Aveiro Campus Universitário de Santiago 3810-193 Aveiro Portugal
2. QOPNA-LAQV-REQUINTE and Department of Chemistry University of Aveiro Campus Universitário de Santiago 3810-193 Aveiro Portugal, CESAM and Department of Biology University of Aveiro Campus Universitário de Santiago 3810-193 Aveiro Portugal
3. Mass Spectrometry Laboratory and Department of Chemistry University of Aveiro Campus Universitário de Santiago 3810-193 Aveiro Portugal
4. CESAM and Department of Biology University of Aveiro Campus Universitário de Santiago 3810-193 Aveiro Portugal
5. CICECO-Aveiro Institute of Materials and Department of Chemistry University of Aveiro Campus Universitário de Santiago 3810-193 Aveiro Portugal
6. CQE and Departamento de Engenharia Química Instituto Superior Técnico, Universidade de Lisboa Av. Rovisco Pais, n°1 1049-001 Lisboa Portugal

Abstract Novel water‐soluble zinc(II) phthalocyanines (ZnPc) peripherally substituted with 4‐dimethylaminopyridine (DMAP) units (ZnPc 1 – 2 ) and the corresponding quaternized derivatives (ZnPc 1 a – 2 a ) were synthesized and their photodynamic inactivation (PDI) efficiency against a Gram‐negative bacterium, a recombinant bioluminescent Escherichia coli strain either in planktonic or biofilm form, was investigated. The analysis of the photophysical properties revealed that the increase in the number of DMAP units on ZnPc shifted the absorption and emission band in aqueous media to the red region. The presence of multi‐positive charges on ZnPc derivatives prevented aggregation and enhances the solubility in aqueous media. The quaternized derivatives ZnPc 1 a and 2 a displayed good stability and promising efficacy to generate singlet oxygen ( ¹ O ₂ ). The affinity of the amphiphilic ZnPc 1 – 2 and quaternized ZnPc 1 a – 2 a to planktonic bacterial cells corresponded to an average uptake of ∼10 ⁶  PS molecules.CFU ⁻¹ . The PDI assays conducted with planktonic cells and biofilms of E. coli show that irradiation with red or white light (150 mW.cm ⁻² ) in the presence of 20 μM of ZnPc derivatives caused an effective inactivation. ZnPc 1 a and ZnPc 2 a exhibited the highest inactivation efficiency, particularly of the planktonic form, causing a 5 log‐scale (99.99 %) reduction in bioluminescence. The inactivation factor for biofilms was 99 % (2 log). ZnPc 1 a and ZnPc 2 a can be regarded as promising photosensitizers for the photodynamic inactivation of Gram‐negative bacteria.

• Sponsoring Organization: USDOE
• OSTI ID: 1511867
• Journal Information: ChemPhotoChem, Journal Name: ChemPhotoChem Vol. 3 Journal Issue: 5; ISSN 2367-0932
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: Germany
• Language: English