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Interaction of Laponite with Membrane Components - Consequences for Bacterial Aggregation and Infection Confinement

Malekkhaiat Häffner, Sara; Nyström, Lina; Browning, Kathryn L.; Mörck Nielsen, Hanne; Strömstedt, Adam A.; Van Der Plas, Mariena J.A. LU ; Schmidtchen, Artur LU and Malmsten, Martin LU (2019) In ACS Applied Materials and Interfaces 11(17). p.15389-15400
Abstract

The antimicrobial effects of Laponite nanoparticles with or without loading of the antimicrobial peptide LL-37 was investigated along with their membrane interactions. The study combines data from ellipsometry, circular dichroism, fluorescence spectroscopy, particle size/ζ potential measurements, and confocal microscopy. As a result of the net negative charge of Laponite, loading of net positively charged LL-37 increases with increasing pH. The peptide was found to bind primarily to the outer surface of the Laponite nanoparticles in a predominantly helical conformation, leading to charge reversal. Despite their net positive charge, peptide-loaded Laponite nanoparticles did not kill Gram-negative Escherichia coli bacteria or disrupt... (More)

The antimicrobial effects of Laponite nanoparticles with or without loading of the antimicrobial peptide LL-37 was investigated along with their membrane interactions. The study combines data from ellipsometry, circular dichroism, fluorescence spectroscopy, particle size/ζ potential measurements, and confocal microscopy. As a result of the net negative charge of Laponite, loading of net positively charged LL-37 increases with increasing pH. The peptide was found to bind primarily to the outer surface of the Laponite nanoparticles in a predominantly helical conformation, leading to charge reversal. Despite their net positive charge, peptide-loaded Laponite nanoparticles did not kill Gram-negative Escherichia coli bacteria or disrupt anionic model liposomes. They did however cause bacteria flocculation, originating from the interaction of Laponite and bacterial lipopolysaccharide (LPS). Free LL-37, in contrast, is potently antimicrobial through membrane disruption but does not induce bacterial aggregation in the concentration range investigated. Through LL-37 loading of Laponite nanoparticles, the combined effects of bacterial flocculation and membrane lysis are observed. However, bacteria aggregation seems to be limited to Gram-negative bacteria as Laponite did not cause flocculation of Gram-positive Bacillus subtilis bacteria nor did it bind to lipoteichoic acid from bacterial envelopes. Taken together, the present investigation reports several novel phenomena by demonstrating that nanoparticle charge does not invariably control membrane destabilization and by identifying the ability of anionic Laponite nanoparticles to effectively flocculate Gram-negative bacteria through LPS binding. As demonstrated in cell experiments, such aggregation results in diminished LPS-induced cell activation, thus outlining a promising approach for confinement of infection and inflammation caused by such pathogens.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
antimicrobial, bacteria flocculation, infection confinement, Laponite, membrane
in
ACS Applied Materials and Interfaces
volume
11
issue
17
pages
12 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85065042549
ISSN
1944-8244
DOI
10.1021/acsami.9b03527
language
English
LU publication?
yes
id
4bbd985c-f556-4823-93f9-cf6751926fcd
date added to LUP
2019-05-13 14:50:23
date last changed
2019-06-04 03:58:01
@article{4bbd985c-f556-4823-93f9-cf6751926fcd,
  abstract     = {<p>The antimicrobial effects of Laponite nanoparticles with or without loading of the antimicrobial peptide LL-37 was investigated along with their membrane interactions. The study combines data from ellipsometry, circular dichroism, fluorescence spectroscopy, particle size/ζ potential measurements, and confocal microscopy. As a result of the net negative charge of Laponite, loading of net positively charged LL-37 increases with increasing pH. The peptide was found to bind primarily to the outer surface of the Laponite nanoparticles in a predominantly helical conformation, leading to charge reversal. Despite their net positive charge, peptide-loaded Laponite nanoparticles did not kill Gram-negative Escherichia coli bacteria or disrupt anionic model liposomes. They did however cause bacteria flocculation, originating from the interaction of Laponite and bacterial lipopolysaccharide (LPS). Free LL-37, in contrast, is potently antimicrobial through membrane disruption but does not induce bacterial aggregation in the concentration range investigated. Through LL-37 loading of Laponite nanoparticles, the combined effects of bacterial flocculation and membrane lysis are observed. However, bacteria aggregation seems to be limited to Gram-negative bacteria as Laponite did not cause flocculation of Gram-positive Bacillus subtilis bacteria nor did it bind to lipoteichoic acid from bacterial envelopes. Taken together, the present investigation reports several novel phenomena by demonstrating that nanoparticle charge does not invariably control membrane destabilization and by identifying the ability of anionic Laponite nanoparticles to effectively flocculate Gram-negative bacteria through LPS binding. As demonstrated in cell experiments, such aggregation results in diminished LPS-induced cell activation, thus outlining a promising approach for confinement of infection and inflammation caused by such pathogens.</p>},
  author       = {Malekkhaiat Häffner, Sara and Nyström, Lina and Browning, Kathryn L. and Mörck Nielsen, Hanne and Strömstedt, Adam A. and Van Der Plas, Mariena J.A. and Schmidtchen, Artur and Malmsten, Martin},
  issn         = {1944-8244},
  keyword      = {antimicrobial,bacteria flocculation,infection confinement,Laponite,membrane},
  language     = {eng},
  number       = {17},
  pages        = {15389--15400},
  publisher    = {The American Chemical Society},
  series       = {ACS Applied Materials and Interfaces},
  title        = {Interaction of Laponite with Membrane Components - Consequences for Bacterial Aggregation and Infection Confinement},
  url          = {http://dx.doi.org/10.1021/acsami.9b03527},
  volume       = {11},
  year         = {2019},
}