We describe a novel superhydrophobic singlet oxygen delivery device for the selective inactivation of bacterial biofilms. This treatment approach relies on transport of singlet oxygen from sensitizer particle surfaces, across the plastron, to the biofilm thereby preventing direct contact between sensitizer molecules and the organism. This approach precludes limitations due to oxygen diffusion, optical absorption, tissue sensitization and potential toxicity. The superhydrophobic surface was synthesized by partially embedding sensitizing particles on polydimethylsiloxane printed posts, capped with silica nanoparticles to prevent direct contact of sensitizer with the bacterial biofilm. Gaseous singlet oxygen is generated on sensitizer particle surfaces in the plastron of the superhydrophobic surface upon irradiation with visible light, and transported to inactivate <i>Porphyromonas gingivalis</i> biofilms on hydroxyapatite discs as monitored by colony counting and LIVE/DEAD staining. The biofilm killing efficiency correlated to the amount of singlet oxygen detected in a separate reaction with 9,10-anthracene dipropionate dianion. The work also compared two sensitizing particle types: a silicon phthalocyanine sol-gel (Si-Pc), and a chlorin e6 derivative covalently bound to fluorinated silica, the former resulted in higher biofilm killing and a 2.4 X higher concentration of trapped singlet oxygen. Thresholds for light fluence and singlet oxygen concentration were determined for complete biofilm inactivation (&gt;5 log killing).

Superhydrophobic photosensitizers: Airborne singlet oxygen killing of an <i>in-vitro</i> oral biofilm at the plastron interface

256th National Meeting (2018)

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Superhydrophobic photosensitizers: Airborne singlet oxygen killing of an in-vitro oral biofilm at the plastron interface