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Proceedings Paper

Plasmonic enhancement in the photoinactivation of Escherichia Coli using rose bengal and gold nanoparticles
Author(s): Heike Kagel; Julia Honselmann Genannt Humme; Edvaldo Antonio Ribeiro Rosa; Rozane de Fátima Turchiello; Arandi Ginane Bezerra Junior
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Paper Abstract

In the present study we report on the ability of gold nanoparticles (AuNP) to enhance the antimicrobial activity of the photosensitizer Rose Bengal (RB), a very effective singlet oxygen generator. Our experiments were conducted using a suspension of Escherichia Coli in the presence of either RB or a combination of RB and AuNP. Nanoparticles were synthesized by laser ablation in water, which allows high purity, biologically friendly AuNP production, as compared to traditional chemical methods. Several relative concentrations of bacteria, photosensitizes and AuNP were studied. Bacterial survival rates were determined before and after LED light illumination. The phototoxicity of RB with and without AuNP was checked following illumination for 10 and 20 minutes. As a control, the dark toxicity of RB was verified. The results show that the survival rate of bacteria decreases significantly with the increase of RB concentration and illumination time, which is in accordance with previous works. Interestingly, our results also indicate a significant increase in the lethal photosensitization of RB in the presence of AuNP. We propose this effect is due to plasmonic light enhancement, considering the superposition of RB and AuNP absorption spectra, which favors electric field enhancement effects in the presence of AuNP. Similar experiments using the photosensitizer Methylene Blue (MB) allowed us to test our hypothesis for MB did not show any difference in its phototoxicity in the presence of AuNP. We propose this observed synergistic effect could be an effective way for improving photodynamic inactivation of microorganisms.

Paper Details

Date Published: 19 June 2015
PDF: 6 pages
Proc. SPIE 9531, Biophotonics South America, 953138 (19 June 2015); doi: 10.1117/12.2180947
Show Author Affiliations
Heike Kagel, Univ. of Applied Sciences (Germany)
Julia Honselmann Genannt Humme, Univ. of Applied Sciences (Germany)
Edvaldo Antonio Ribeiro Rosa, Biological and Health Sciences Ctr., Pontifical Catholic Univ. of Paraná (Brazil)
Rozane de Fátima Turchiello, Univ. Federal do Parana (Brazil)
Arandi Ginane Bezerra Junior, Univ. Federal do Parana (Brazil)

Published in SPIE Proceedings Vol. 9531:
Biophotonics South America
Cristina Kurachi D.D.S.; Katarina Svanberg M.D.; Bruce J. Tromberg; Vanderlei Salvador Bagnato, Editor(s)

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