Smart Surfaces for the Control of Bacterial Attachment and Biofilm Accumulation

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Smart Surfaces for the Control of Bacterial
Attachment and Biofilm Accumulation

• Linnea K. Ista and Gabriel P. Lopez
• Center for Biomedical Engineering
• Department of Chemical and Nuclear Engineering
• The University of New Mexico
• Smart Coatings Symposium
• 15 February, 2006
• Orlando, Florida

The University of New Mexico
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Bacterial attachment and biofilm formation

• The accumulation of bacteria, bacterial
  metabolites and small organics on a surface
• Specialized ecological niche
• Separate developmental form of bacteria
• Resistant to antimicrobial agents, desiccation,
• Increased nutritional concentration
• Increased genetic exchange

OToole et al, Annu. Rev. Microbiol. 2000,
5949-79
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Why do we want to control biofilm
formation/bacterial adhesion?

• To promote adhesion
• Antibiotic production
• Fermentation
• Bioremediation
• Biosensing applications

• To deter adhesion
• Medical implants
• Ship hulls/oil platforms
• Environmental systems
• Non specific adsorption in assays

• To enable reversible attachment and detachment
• Preconcentration
• Fundamental studies of biofilm development

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How can we control biofilm formation/bacterial
adhesion?
Surfaces that resist bacterial attachment
Ista, et al, FEMS Microbiol. Lett. 1996.
14959-63
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How can we control biofilm formation/bacterial
adhesion?
Surfaces that resist bacterial attachment
Surfaces with biocidal activity
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How can we control biofilm formation/bacterial
adhesion?
Surfaces that resist bacterial attachment
Surfaces with biocidal activity
Fouling release surfaces
Ista and Lopez, J. Industr. Microbiol.
Biotechnol, 1998. 20121-125
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Smart polymers as fouling release surfaces
Exploit interfacial phase transitions for fouling
release
Poly (N-isopropylacrylamide) PNIPAAM Solubility
phase transition 32oC
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Smart polymers as fouling release surfaces
Exploit interfacial phase transitions for fouling
release
Poly(N-isopropylacrylamide) PNIPAAM Solubility
phase transition 32oC
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Attachment/detachment studies
Sample
Samples incubated in bacterial suspension at
incubation temperature (2-72 hr)
Sample rinsed with deionized H2O at incubation
temperature
Count number of attached cells 60x, phase
contrast
Rinse with 60 mL release temperature buffer,
followed by a rinse in deionized H2O
Count number of attached cells 60x, phase
contrast
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What happened?
Cobetia marina (formerly Halomonas marina) ATCC
25374

• Gram negative
• Obligately aerobic
• Marine source -Pacific
• Motile by gliding (mostly) or flagella

Ista, et al, Appl. Eviron. Microbiol 1999.
651603-1609
Incubation temp. 37OC release 4oC
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What happened?
Staphylococcus epidermidis ATCC 14990
No release upon transition when attached at 37oC
and rinsed at 4oC!

• Gram positive
• Facultative anaerobe
• Skin bacteria- medically relevant
• Non motile

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Why? Attachment to SAMs

• Self Assembled Monolayers of ?-substituted
  alkanethiolates on gold
• Well ordered surface
• Can express a single or multiple moieties on the
  surface
• Can do chemical modification on the surface
• Gold can be made any thickness, allowing for a
  variety of analytical techniques

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Why? Attachment to SAMs
C. marina
S. epidermidis
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Changing attachment/detachment temperature regime
results in removal of S. epidermidis
S. epdermidis Incubation at 25oC 72 hours
S. epidermidis After rinsing with 37oC PBS
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Both newly attached cells and biofilms can be
released using this method
C. marina attach at 37oC Release at 4oC
S. epidermidis attach at 25oC release at 37oC
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Exploring the effects of changing
physicochemistry on fouling release using PNIPAAM
grafted from SAMs
Ista, et al, Langmuir, 2001 652552-2555
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Exploring the effects of changing hydrophobicity
on fouling release using PNIPAAM grafted from SAMs
Atom transfer radical polymerization
(Balamurguran, et al. Langmuir, 2003, 192545-2549
R-Br Cu(I)BrL

• Advantages of ATRP
• Free radical is formed only at the surface
  eliminating undesired reactions caused by
  solution free radicals
• Surface coverage can be varied by altering the
  surface mole of OH-terminated thiolate in the
  SAM
• Length of polymer can be controlled by time of
  polymerization.
• Room temperature polymerization
• Slow reaction results in increased monodispersity

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Changing hydrophobicity by changing the comonomer
Copolymerization with tert-butyl acrylamide
results in surfaces on which the overall
hydrophobicity is higher.
Change in ?Aw PNIPAAM 60o to 42o P 21 78o to
63o P 14 81o to 60o
With Drs. Sreelatha and Subramanian Balamurugaran
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C. marina attach 37oC release 4OC
Changes in temperature result in different
attachment and detachment behavior
C. marina attach 25oC release 4OC
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Using tunable PNIPAAM to examine effect of
changing hydrophobicity
Mendez, et al, Langmuir, 2003. 198115-8116
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Attachment to tunable PNIPAAM
S. epidermidis attach 25oC
C. marina attach 37oC
With Dr. Sergio Mendez
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Release from tunable PNIPAAM
S. epidermidis attach 25oC Release 37oC
C. marina attach 37oC release 4OC
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Toward practical coatingssilica/smart polymer
composites
PNIPAAM
Silica network
With Dr. V.G. Rama Rao
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Smart polymer-silica composites both resist
attachment and promote release
C. marina Attach 2 hr 37oC release 4oC
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Mixed oligo(ethylene glycol)/ methyl terminated
sams a new smart material for biofilm release?
Prime and Whitesides, J. Amer. Chem. Soc. 1993,
115 10714- 10721
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Balamurugaran, et al, J. Amer. Chem Soc. 2005.
12714548-14549
C. marina Attach 2 hr 37oC release 4oC
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Acknowledgements

• Sergio Mendez, Sreelatha Balamurugaran,
  Subramanian Balamurugaran, G.V. Rama Rao
• Robin Simons
• Office of Naval Research
• Sandia National Labs

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Thank you!
Any questions?