Efficient photodynamic therapy against Staphylococcus aureus using
[Ru(bpy)2(dppn)]2+: a novel cationic photosensitizer

Yucheng Wang; Ying Wang; Ying Gu

doi:10.1117/12.999540

11 December 2012 Efficient photodynamic therapy against Staphylococcus aureus using [Ru(bpy)₂(dppn)]²⁺: a novel cationic photosensitizer

Yucheng Wang, Ying Wang, Ying Gu

Author Affiliations +

Proceedings Volume 8553, Optics in Health Care and Biomedical Optics V; 85530H (2012) https://doi.org/10.1117/12.999540
Event: Photonics Asia, 2012, Beijing, China

Abstract

[Ru(bpy)₂(dppn)]²⁺, one of Ru(II) polypyridyl complexes, present inner dicationic charge and high ¹O₂ quantum yield. In this study, the synthetic compound was used as photosensitizer (PS) to photoinactivate a reference strain of Staphylococcus aureus ATCC 25923. Bacterial suspensions consisting of 10⁸ colony-forming units (CFU) per milliliter were incubated with PS of different concentrations (0.025μM ~ 25μM). After a 30 minutes period, the suspensions were exposed to 457nm laser light, determined by the absorption spectra of the PS in phosphate buffered saline (PBS), with a power density of 40 mW/cm² for 10 minutes (energy density of 24 J/cm²). PS group, light group and the blank control were also concerned. Viability of bacteria was determined by pour plates. The Log₁₀ reductions were calculated and killing effects in photodynamic inactivation (PDI) group were analysed contrast to the blank control. We observed that neither the laser light nor the PS per se had any inhibitory effect on the viability of the bacteria. PS at low dose (0.025μM) followed by illumination yielded no significant decrease in the viable number. PS at 0.25μM and 2.5μM with irradiation induced reductions of 1.69 Log₁₀ and 5.97 Log₁₀, respectively. PS at 10μM and 25μM combined with light brought viable bacterial cells down to undetectable levels (reductions < 7 Log₁₀). We concluded that with the PS of appropriate doses, [Ru(bpy)₂(dppn)]²⁺ mediated PDI inactivated S.aureus efficiently. At the concentration of 2.5μM, bactericidal activity was reached where the viability of bacteria fell more than 3 Log₁₀ based on previous researches.

Citation Download Citation

Yucheng Wang, Ying Wang, and Ying Gu "Efficient photodynamic therapy against Staphylococcus aureus using [Ru(bpy)₂(dppn)]²⁺: a novel cationic photosensitizer", Proc. SPIE 8553, Optics in Health Care and Biomedical Optics V, 85530H (11 December 2012); https://doi.org/10.1117/12.999540

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