The importance of superoxide anion for Escherichia coli biofilm removal using plasma-activated water

Xia, B; Vyas, HKN; Zhou, R; Zhang, T; Hong, J; Rothwell, JG; Rice, SA; Carter, D; Ostrikov, K; Cullen, PJ; Mai-Prochnow, A

The importance of superoxide anion for Escherichia coli biofilm removal using plasma-activated water

Xia, B Vyas, HKN Zhou, R Zhang, T Hong, J Rothwell, JG Rice, SA Carter, D Ostrikov, K Cullen, PJ Mai-Prochnow, A

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Publisher:: ELSEVIER SCI LTD
Publication Type:: Journal Article
Citation:: Journal of Environmental Chemical Engineering, 2023, 11, (3)
Issue Date:: 2023-06-01

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Field	Value	Language
dc.contributor.author	Xia, B
dc.contributor.author	Vyas, HKN
dc.contributor.author	Zhou, R
dc.contributor.author	Zhang, T
dc.contributor.author	Hong, J
dc.contributor.author	Rothwell, JG
dc.contributor.author	Rice, SA
dc.contributor.author	Carter, D
dc.contributor.author	Ostrikov, K
dc.contributor.author	Cullen, PJ
dc.contributor.author	Mai-Prochnow, A
dc.date.accessioned	2024-01-12T02:47:43Z
dc.date.available	2024-01-12T02:47:43Z
dc.date.issued	2023-06-01
dc.identifier.citation	Journal of Environmental Chemical Engineering, 2023, 11, (3)
dc.identifier.issn	2213-2929
dc.identifier.issn	2213-3437
dc.identifier.uri	http://hdl.handle.net/10453/174347
dc.description.abstract	Microbial biofilms cause contaminations in different environmental settings, including pipelines, filters, membranes, food and processing infrastructure. They ultimately pose a major risk to human health and necessitate costly cleaning and repair. Cold plasma, a partially ionised gas, and plasma-activated water (PAW) exhibit powerful disinfectant activity. However, the optimal generating conditions, such as the choice of gas used to produce PAW, remain unclear. Here, a range of different PAWs were generated from argon, nitrogen, air, and oxygen in a plasma bubble spark discharge (BSD) reactor capable of directly treating Escherichia coli (ATCC 25922) biofilms in situ. We measured the reactive oxygen and nitrogen species (RONS) (H2O2, NO3-, NO2-) in PAW and the excited species via optical emission spectroscopy (OES). PAW generated using oxygen (PAW-O2) was the most effective and completely removed E. coli biofilms on stainless steel surfaces. Confocal microscopy demonstrated that PAW treatment removed most biofilm cells from the surface with only a few dead cells remaining. We demonstrated that intracellular ROS level increases significantly in the PAW-O2-treated biofilms. Using molecular scavengers, we showed that superoxide anion radical (•O2-) played a critical role in the inactivation of E. coli biofilms. We also confirmed the generation of •O2- in the PAW-O2 via electron paramagnetic resonance (EPR) spectrometry. The potential chemical reactions that occurred in PAW were hypothesized via optical emission spectra (OES). Our results demonstrate the importance of input gas and plasma operating conditions to maximise effective RONS production for optimal biofilm removal under real environmental and industry-relevant conditions.
dc.language	English
dc.publisher	ELSEVIER SCI LTD
dc.relation	http://purl.org/au-research/grants/arc/DP210101358
dc.relation.ispartof	Journal of Environmental Chemical Engineering
dc.relation.isbasedon	10.1016/j.jece.2023.109977
dc.rights	info:eu-repo/semantics/openAccess
dc.subject	0306 Physical Chemistry (incl. Structural), 0904 Chemical Engineering, 0907 Environmental Engineering
dc.subject.classification	3406 Physical chemistry
dc.subject.classification	4004 Chemical engineering
dc.subject.classification	4011 Environmental engineering
dc.title	The importance of superoxide anion for Escherichia coli biofilm removal using plasma-activated water
dc.type	Journal Article
utslib.citation.volume	11
utslib.for	0306 Physical Chemistry (incl. Structural)
utslib.for	0904 Chemical Engineering
utslib.for	0907 Environmental Engineering
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
utslib.copyright.status	open_access	*
dc.date.updated	2024-01-12T02:47:41Z
pubs.issue	3
pubs.publication-status	Published
pubs.volume	11
utslib.citation.issue	3

Abstract:

Microbial biofilms cause contaminations in different environmental settings, including pipelines, filters, membranes, food and processing infrastructure. They ultimately pose a major risk to human health and necessitate costly cleaning and repair. Cold plasma, a partially ionised gas, and plasma-activated water (PAW) exhibit powerful disinfectant activity. However, the optimal generating conditions, such as the choice of gas used to produce PAW, remain unclear. Here, a range of different PAWs were generated from argon, nitrogen, air, and oxygen in a plasma bubble spark discharge (BSD) reactor capable of directly treating Escherichia coli (ATCC 25922) biofilms in situ. We measured the reactive oxygen and nitrogen species (RONS) (H2O2, NO3-, NO2-) in PAW and the excited species via optical emission spectroscopy (OES). PAW generated using oxygen (PAW-O2) was the most effective and completely removed E. coli biofilms on stainless steel surfaces. Confocal microscopy demonstrated that PAW treatment removed most biofilm cells from the surface with only a few dead cells remaining. We demonstrated that intracellular ROS level increases significantly in the PAW-O2-treated biofilms. Using molecular scavengers, we showed that superoxide anion radical (•O2-) played a critical role in the inactivation of E. coli biofilms. We also confirmed the generation of •O2- in the PAW-O2 via electron paramagnetic resonance (EPR) spectrometry. The potential chemical reactions that occurred in PAW were hypothesized via optical emission spectra (OES). Our results demonstrate the importance of input gas and plasma operating conditions to maximise effective RONS production for optimal biofilm removal under real environmental and industry-relevant conditions.

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http://hdl.handle.net/10453/174347