Carbn Nanotubes Interaction With Bacterial Cell
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Transcript of Carbn Nanotubes Interaction With Bacterial Cell
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Interaction of Carbon Nanotubeswith Bacterial Cells
Menachem Elimelech
Department of Chemical Engineering
Environmental Engineering Program
Yale University
UCLA/CNSI workshop Bio-physicochemical
Interactions of Engineered Nanomaterials,
September 10, 2007
http://www.yale.edu/env/elimelech/publication-pdf/Kang_et_al_LANGMUIR_2007.pdfhttp://www.yale.edu/env/elimelech/publication-pdf/Kang_et_al_LANGMUIR_2007.pdfhttp://www.yale.edu/env/elimelech/publication-pdf/Kang_et_al_LANGMUIR_2007.pdf -
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Richard Smalley (2005): These nanotubesare so beautiful that they must be useful for
something. . .
! Drug delivery! Biomaterials
! Sensors
! Semiconductors
! Novel materials! Photonics
! Catalytic support
! Environmental applications
Single-Walled Carbon Nanotubes
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Biocompatibility of Single-Walled
Carbon Nanotubes (SWNTs)
Numerous proposed biological applications
of SWNTs, e.g., biosensors, drug delivery,
and novel biomaterialsIncreased potential for encounters between
SWNTs and humans and ecosystem
Concerns about SWNT toxicity
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Can SWNT apparent biotoxicity be
used for beneficial applications, e.g.,antimicrobial surfaces?
ObjectivesTo study the interaction of SWNTs with
bacterial cells
To determine whether SWNTs possess
antibacterial properties
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Preparation of Well-Defined Single-
Walled Carbon Nanotubes
Silica template
MCM-41 (D=2.8 nm)
3% Co incorporated
Purification
Template removal byNaOH
Co removal by reflux
in HCl
Growth
Reduced in hydrogenat 975 K
CO disproportionation
at 6 atm and 1125 K
MCM-41
Template
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SWNT Properties
Physical characteristics: Diameter: 0.9 nm (0.75 -
1.2 nm)
Length: 1 - 3 m
Chemical characteristics: Metal content: 0.8 %
(w/w) Co
Negligible amorphous
carbon
No significant changes
during purification
(Raman)
0 500 1000 1500 2000
0
2000
4000
6000
8000
10000
Intensity(a.u.
)
Raman shift (cm-1)
SWNTs as produced
purified SWNTs
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Model Bacterium
E. coliK12
Grown in LB broth; harvested at
exponential growth phaseWashed twice with 0.9 % NaCl (isotonic
solution)
Enumerated by OD600nm and cell countingchamber
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Viability Assay
Suspended SWNTs
0.9 %NaCl
SWNT(5 mg/L) Cells(5x107/mL)
Incubation
for 1 hr
0.9 %NaCl
PI(50 g/mL) DAPI(3 g/mL)
Free swimming
Attached
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Viability Assay
Deposited SWNTs
Vacuum filtration
of 4 mg SWNT
Incubation
PI(50 g/mL)
DAPI(3 g/mL)
Filtration of cells
(2x106 cells)
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Viability Assay
Metabolic activity 5-cyano-2,3-ditolyl-tetrazolium chloride (CTC)
Filtration of cells
(2x106 cells) DAPI(after 1 hr)
Incubation
for 30 min.
CTC(50 g/mL)
Minimal medium
with glucose
Incubation
for 1 hr
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Biotoxicity of SWNTs
SWNT aggregates Total cells (stained with both)
Damaged cells (PI stained) Free swimming cells
100 m
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Biotoxicity of SWNTs
Control SWNT Control SWNT0
20
40
60
80
100
B
iotoxicity
(%)
Suspended Deposited
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Biotoxicity of SWNTs
Metabolic activity (CTC-staining) with andwithout SWNTs
Control SWNT0
20
40
60
80
100
Activ
eCells(%)
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Cell Membrane Damage
Morphological change: SEM images
Control (without SWNT) SWNT
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Control SWNT
0
100
200
300
400
DNACo
nc.
(ng/mL)
Cell Membrane Damage
Efflux of intracellular materials (plasmidDNA) into solution
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Concluding Remarks
SWNTs exhibit strong antibacterial
activity
Direct contact of bacteria with SWNTs isnecessary for inactivation
Severe cell membrane damage after
contact with SWNTs
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Acknowledgments
Prof. Lisa Pfefferle
Steve Kang (post-doc)
Funding: NSF