Bacterial Inactivation by a Singlet Oxygen Bubbler: Identifying Factors Controlling the Toxicity of 1O2 Bubbles

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• 作者：Dorota Bartusik ; David Aebisher ; Alan M. Lyons ; Alexander Greer
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：November 6, 2012
• 年：2012
• 卷：46
• 期：21
• 页码：12098-12104
• 全文大小：289K
• 年卷期：v.46,no.21(November 6, 2012)
• ISSN：1520-5851

文摘

A microphotoreactor device was developed to generate bubbles (1.4 mm diameter, 90 渭L) containing singlet oxygen at levels toxic to bacteria and fungus. As singlet oxygen decays rapidly to triplet oxygen, the bubbles leave behind no waste or byproducts other than O₂. From a comparative study in deaerated, air saturated, and oxygenated solutions, it was reasoned that the singlet oxygen bubbles inactivate Escherichia coli and Aspergillus fumigatus, mainly by an oxygen gradient inside and outside of the bubble such that singlet oxygen is solvated and diffuses through the aqueous solution until it reacts with the target organism. Thus, singlet oxygen bubble toxicity was inversely proportional to the amount of dissolved oxygen in solution. In a second mechanism, singlet oxygen interacts directly with E. coli that accumulate at the gas鈥搇iquid interface although this mechanism operates at a rate approximately 10 times slower. Due to encapsulation in the gaseous core of the bubble and a 0.98 ms lifetime, the bubbles can traverse relatively long 0.39 mm distances carrying ¹O₂ far into the solution; by comparison the diffusion distance of ¹O₂ fully solvated in H₂O is much shorter (150 nm). Bubbles that reached the outer air鈥搘ater interface contained no ¹O₂. The mechanism by which ¹O₂ deactivated organisms was explored through the addition of detergent molecules and Ca²⁺ ions. Results indicate that the preferential accumulation of E. coli at the air鈥搘ater interface of the bubble leads to enhanced toxicity of bubbles containing ¹O₂. The singlet oxygen device offers intriguing possibilities for creating new types of disinfection strategies based on photodynamic (¹O₂) bubble carriers.