Superhydrophobic Photosensitizers: Airborne 1O2 Killing of a In-vitro Oral Biofilm at the Plastron Interface

Smruti Pushalkar, Goutam Ghosh, Qian Feng Xu, Yang Liu, Ashwini A. Ghogare, Cecilia Atem, Alexander Greer, Deepak Saxena, Alan M. Lyons

Research output: Contribution to journalArticle

Abstract

Singlet oxygen is a potent agent for the selective killing of a wide range of harmful cells, however current delivery methods pose significant obstacles to its widespread use as a treatment method. Limitations include: the need for photosensitizer proximity to tissue because of the short (3.5 μs) lifetime of singlet oxygen in contact with water; the strong optical absorption of the photosensitizer, which limits penetration depth; and hypoxic environments that restrict the concentration of available oxygen. In this article, we describe a novel superhydrophobic singlet oxygen delivery device for the selective inactivation of bacterial biofilms. The device addresses the current limitations by: immobilizing photosensitizer molecules onto inert silica particles; embedding the photosensitizer containing particles into the plastron (i.e. the fluid-free space within a superhydrophobic surface between the solid substrate and fluid layer); distributing the particles along an optically transparent substrate such that they can be uniformly illuminated; enabling the penetration of oxygen via the contiguous vapor space defined by the plastron; and stabilizing the superhydrophobic state while avoiding direct contact of the sensitizer to biomaterials. In this way, singlet oxygen generated on the sensitizer-containing particles can diffuse across the plastron and kill bacteria even deep within hypoxic periodontal pockets. For the first time, we demonstrate complete biofilm inactivation (>5 log killing) of Porphyromonas gingivalis, a bacterium implicated in periodontal disease. The biofilms were cultured on hydroxyapatite discs and exposed to active and control surfaces to assess killing efficiency as monitored by colony counting and confocal microscopy. Two sensitizer particle types: a silicon phthalocyanine sol-gel (Si-Pc), and a chlorin e6 derivative covalently bound to fluorinated silica, were evaluated; the biofilm killing efficiency was found to correlate with the amount of singlet oxygen detected in separate trapping studies. Finally, we discuss applications for such devices in the treatment of periodontitis.

Original languageEnglish (US)
JournalACS Applied Materials and Interfaces
DOIs
StateAccepted/In press - Jun 6 2018

Fingerprint

Singlet Oxygen
Photosensitizing Agents
Photosensitizers
Biofilms
Oxygen
silicon phthalocyanine
Silicon Dioxide
Bacteria
Fluids
Control surfaces
Confocal microscopy
Biocompatible Materials
Substrates
Silica
Durapatite
Light absorption
Particles (particulate matter)
Sol-gels
Vapors
Hydroxyapatite

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Superhydrophobic Photosensitizers : Airborne 1O2 Killing of a In-vitro Oral Biofilm at the Plastron Interface. / Pushalkar, Smruti; Ghosh, Goutam; Xu, Qian Feng; Liu, Yang; Ghogare, Ashwini A.; Atem, Cecilia; Greer, Alexander; Saxena, Deepak; Lyons, Alan M.

In: ACS Applied Materials and Interfaces, 06.06.2018.

Research output: Contribution to journalArticle

Pushalkar, Smruti ; Ghosh, Goutam ; Xu, Qian Feng ; Liu, Yang ; Ghogare, Ashwini A. ; Atem, Cecilia ; Greer, Alexander ; Saxena, Deepak ; Lyons, Alan M. / Superhydrophobic Photosensitizers : Airborne 1O2 Killing of a In-vitro Oral Biofilm at the Plastron Interface. In: ACS Applied Materials and Interfaces. 2018.
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