Oligolysine-conjugated zinc(II) phthalocyanines as efficient photosensitizers for antimicrobial photodynamic therapy

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Mei-Rong Ke
  • Jennifer Mary Eastel
  • Karry L. K. Ngai
  • Yuk-Yam Cheung
  • Paul K. S. Chan
  • Mamie Hui
  • Dennis K. P. Ng

Detail(s)

Original languageEnglish
Pages (from-to)1868-1875
Journal / PublicationChemistry - An Asian Journal
Volume9
Issue number7
Publication statusPublished - Jul 2014
Externally publishedYes

Abstract

A series of zinc(II) phthalocyanines conjugated with an oligolysine chain (n=2, 4, and 8) were synthesized and characterized by using various spectroscopic methods. As shown by using UV/Vis and fluorescence spectroscopic methods, these compounds were nonaggregated in N,N-dimethylformamide, and gave a weak fluorescence emission and high singlet oxygen quantum yield (ΦΔ=0.86-0.89) as a result of their di-α- substitution. They became slightly aggregated in water with 0.05 % Cremophor EL, but they could still generate singlet oxygen effectively. The antimicrobial photodynamic activities of these compounds were then examined against various bacterial strains, including the Gram-positive methicillin-sensitive Staphylococcus aureus ATCC 25923 and methicillin-resistant Staphylococcus aureus ATCC BAA-43, and the Gram-negative Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 27853. Generally, the dyes were much more potent toward the Gram-positive bacteria. Only 15 to 90 nM of these photosensitizers was required to induce a 4 log reduction in the cell viability of the strains. For Escherichia coli, the photocytotoxicity increased with the length of the oligolysine chain. The octalysine derivative showed the highest potency with a 4 log reduction concentration of 0.8 μM. Pseudomonas aeruginosa was most resistant to the photodynamic treatment. The potency of the tetralysine derivative toward a series of clinical strains of Staphylococcus aureus was also examined and found to be comparable with that toward the nonclinical counterparts. Moreover, the efficacy of these compounds in photodynamic inactivation of viruses was also examined. They were highly photocytotoxic against the enveloped viruses influenza A virus (H1N1) and herpes simplex virus type 1 (HSV1), but exhibited no significant cytotoxicity against the nonenveloped viruses adenovirus type 3 (Ad3) or coxsackievirus (Cox B1). The octalysine derivative also showed the highest potency with an IC50 value of 0.05 nM for the two enveloped viruses. Resistance is futile: A series of zinc(II) phthalocyanines conjugated with an oligolysine chain (n=2, 4, and 8) were synthesized and characterized. Upon illumination, they exhibited high cytotoxicity toward a range of bacteria, including some drug-resistant and clinical strains, and enveloped viruses. The results show that these specially designed phthalocyanines are promising photosensitizers for antimicrobial photodynamic therapy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Research Area(s)

  • antimicrobials, bacteria, photodynamic therapy, photosensitizers, phthalocyanines, viruses

Citation Format(s)

Oligolysine-conjugated zinc(II) phthalocyanines as efficient photosensitizers for antimicrobial photodynamic therapy. / Ke, Mei-Rong; Eastel, Jennifer Mary; Ngai, Karry L. K.; Cheung, Yuk-Yam; Chan, Paul K. S.; Hui, Mamie; Ng, Dennis K. P.; Lo, Pui-Chi.

In: Chemistry - An Asian Journal, Vol. 9, No. 7, 07.2014, p. 1868-1875.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review